Geological Survey of Brazil under spotligth (distr v2) by cprm

Focu s on Dev elop men t Of Bra zilia n Min eral Sect or

SGB-CPRM

Brazil Geological Survey Under the Spotlight

SGB-CPRM Programs: Program I Geological Geophysical Integration and Predictive Mapping of Brazilian Shields

Program II Basic Geological Mapping

Program III Mineral Potential Assessement of the Brazilian Volcano-sedimentar Sequences

Project Areas: Carajás Fe, Mn, Cu-Au, Ni, Au-PGE, PGE-Ni, Au-Mo-W-S, Cu-Zn, Sn.

Tapajós Au, Au-Cu, Sn, W

Quadrilátero Ferrífero Fe, Au, Mn, Sn, Au-U

Alta Floresta Au, Au-Cu, Zn-Pb-Cu-Au

Borborema (Seridó) W, Au, Fe, Fe-Ti, Cr, Cr-PGE, Cu, Pb-Zn

Program IV Crustal Evolution and Metallogeny of the Brazilian Mineral Provinces

Program V Thematic Projects

Nova Brasilândia Zn-Pb, Au

NW Ceará Cu, Pb-Zn, Mn

Gurupi Au

Brazil

South America There is a global consensus: Brazil is one of the top players in the mining industry. The country has a huge area (8.5M km2), 43% with poten al for iron ore, precious and base metals, diamonds, bauxite, manganese, n, rare earths, graphite and other mineral commodi es. Brazil, with high fer lity but low maturity, considering the very low levels of investments in mineral explora on, has a signiﬁcant poten al for new discoveries. The Geological Survey of Brazil (CPRM) is providing the state of the art of the mineral poten al of the country with focus in the main provinces, like Carajás, Iron Quadrangle and others. The current study consolidates the knowledge accumulated during the last decades and is the result of the integra on of disciplines like geology, geochemistry, geophysics and metallogenesis. Please ﬁnd in this document a summary of some of the most important mineral provinces of Brazil. We are quite sure the herein informa on can result in great exploratory programs, leveraging the mineral explora on and adding value to the Brazilian mining sector.

Eduardo J. Ledsham President of CPRM - Geological Survey of Brazil

Produced by

DGM - Directory of Geology and Mineral Resource José L.S. Andrio

- Director

Editors Noevaldo A. Teixeira (noevaldo.teixeira@cprm. gov. br) and Marco T. N. Carvalho (marco.naves@cprm.gov.br)

Reviewers Joana Tiago Reis Magalhães Mahyra Ferreira Tedeschi Chris an Michel Lacasse Julio Murilo Mar no Pinho Rafael Bi encourt Lima

Contributors Iago S.L.Costa, Loiane G.M. Rocha, Raphael T. Correa, Warley A. Pereira, Paulo Varão, Joseneusa Rodrigues, Marcelo S. Marinho

Aknowledgements ADIMB Vale S.A. Mineração Santa Elina Serabi Gold plc AngloGold Ashan

TEIXEIRA, Noevaldo A., ed. T266b

Brazil : Geological Survey Under the Spotlight / Editores Noevaldo A Teixeira e Marco T. N. Carvalho. – Brasília : CPRM, 2017. 54 p.; il. color. Inclui Referências Bibliográﬁcas

1. Geologia – Brasil. 2. Recursos Minerais – Brasil. 3. Serviço Geológico do Brasil. I. Carvalho, Marco T. N., ed. II. Título CDD 558.1

Indexes for systematic catalog 1.Geologia : Brasil 2.Recursos Minerais : Brasil 3.3. Serviço Geológico do Brasil

558.1 553.0981 352.081

2017

Under The Spotlight

NW Ceará

Carajás Tapajós

Seridó Nova Brasilândia

Juruena-Teles Pires

Quadrilátero Ferrífero

L E G E N D 0

500km

Intracratonic Basins Mobile Belts Cratons

Highlights BRAZIL ü Brazil is a world key player in the mining sector

ü Compared with countries of similar geological

and it will continue to be. All the efforts are being made by the Brazilian Government to bring back the attractiveness of the country, including major investments by the Geological Survey of Brazil (CPRM) to generate high quality geological, geophysical and geochemical data.

setting, as Australia and Canada, Brazil has much less investments in mineral exploration a n d i t s ex p l o rato r y p o te nt i a l re m a i n s underestimated. ü Brazil is one of the world leading producers of

niobium, iron ore, vermiculite, bauxite, graphite and kaolin as well as an important exporter of tin, nickel, magnesite, manganese, chromium, gold and dimension stones.

ü Most of the Brazilian cratonic areas are already

covered by airborne magnetic and radiometric survey with 500-m line spacing. Semi-regional geochemical sampling and assessment already cover many parts of the main mineral provinces. Geological mapping at 1:100.000 scale focused on areas with greater mineral potential is in progress. All the data is available at no cost by simple download from CPRM website.

ü Despite its large potential, Brazil imports

copper, sulfur, titanium, phosphate, diatomite and zinc, and has a deep external dependence on coal, potassium and ETR. The window of opportunities includes opportunities for small to world-class mines. ü Gold and diamond productions are rising,

ü The geological endowment of Brazil is similar to

b a s e d o n n ew d i s cove r i e s a n d m i n i n g development.

the major ore producing countries, such as Australia, Canada and South Africa. 43% of the onshore area is covered by Neoproterozoic-toArchean terrains, with high potential for metals.

ü Little deep mineral exploration has been done

in Brazil, including in “mature” provinces such as the Quadrilátero Ferrífero. Less than 15

underground mines of gold, chromite, copper and zinc are currently in operation in Brazil. It corresponds to less than 4% of the total number of mines. There is an increasing potential for deep discoveries and new mines development.

ü Current known resources and reserves exceed

ü Archean and Paleoproterozoic greenstone belts

ü AngloGold Ashanti produced 421,000 Oz Au in

are widely distributed in Brazil, both in São Francisco, Amazon and São Luís cratons. There is a clear potential for significant new discoveries there, including for gold and sulfide nickel.

2015 in three mines (Cuiabá, Lamego and Córrego do Sítio), while Jaguar Mining produced 96,536 Oz through three other operations (Turmalina, Pilar and Roça Grande mines) in 2016.

ü The country has a real potential for new

ü There are currently 52 iron ore mines in

20 MOz. There are six gold mines in operation. The two major deposits are Morro Velho which produced 470t of gold between 1725 and 2003, and Cuiabá with 150t of gold in past production and reserves.

discoveries linked to randomic Earth´s mantle processes: carbonatites, IOCG, intraplate magmatic gold deposits, TZ diamonds and epithermal gold in anorogenic complexes.

operation at QF, some in care-and-maintenance due the low commodity prices in 2016. More than 12 billion tons or iron ore has already been produced at QF, with grades above 50%.

ü Brazil has an important history of alluvial

ü The western portion of the QF, where the

Turmalina mine (Jaguar) is located, presents expressive occurrences of komatiite flows, felsic pyroclastic rocks, sulfide facies BIF and unusual clay epithermal alteration systems. A new discovery by Iamgold (São Sebastião) confirms the high potential for this underexplored portion of the QF.

diamond production. The current number of known kimberlites, lamproites and related rocks is 1,344, but there is just one primary mine, producing high quality gemstones (Braúna Mine, in Bahia State).. ü The world-class discovery of the Zn-Cu

Aripuanã deposit opens a new exploratory frontier related to Paleoproterozoic continental rifts, particularly in northern Mato Grosso and Rondônia states.

Carajás

ü The possibility of new Cu-Au discoveries in the

ü The Carajás Mineral Province (CMP) is one the

Goiás Magmatic Arc is significant. Recent u n d e rs ta n d i n g o n m e ta m o r p h i s m a n d deformation superimposed to the porphyrystyle mineralization has emerged.

ü The iron ore deposits have the highest grades

largest polymetallic mineral provinces in the world and the second largest IOCG (Cu-Au) province.

cratons, with known tidal-flats and organic lagoon sedimentary facies, are still unexplored for Morro do Ouro type gold mineralization (Kinross; >20 MOz Au).

in the world. Current iron ore resources and reserves are >20 billion tonnes, with >65% Fe. Vale currently operates iron ore mines at the northern (N4 and N5) and southern (S11D) portions of CMP.

ü The Brazilian potential for Ni in magmatic

ü There are four copper-gold mines currently in

conduits, Iron oxide-nickel-copper (IOCG and IONC) mineralization and Zn-Cu sedimentrelated to the intracratonic rifts in the Amazônia is considered very high.

ü The nickel produced at Carajás comes from the

ü The Neoproterozoic belts in the margin of the

operation at Carajás: Salobo (200,000 tpy; Vale), Sossego and Sequeirinho (100,000 tpy combined; Vale), Antas North (Avanco Resources). Onça-Puma laterite nickel operation, with production of 24,400 tonnes in 2015. Other important deposits are Vermelho, Jacaré, Jacarezinho and Mundial.

Quadrilátero Ferrífero ü The Quadrilátero Ferrífero is one of the most

important mineral provinces in the world. First gold discovery dates from 1695, with continuous production since then (>50 MOz Au).

ü Other mines in operation at Carajás include the

Azul and Buritirama manganese mines and small cassiterite operations at São Felix do Xingu region.

ü Carajás is a polycyclic geological province with

Juruena – Teles Pires

several mineralizing periods and different types of deposits: Cu-Au-Zn, PGE-Ni reef, IOCG, IONC, Cu-(Au-Mo-W-Sn), Cu-Au-Mo-F, Fe, Mn, laterite nickel.

ü The Alta Floresta Mineral Province (AFMP)

extends from northern Mato Grosso State to Amazonas State. A prolific gold trend of 600-km length was responsible for a past production of 300t Au, as represented by the Alta Floresta Gold Province.

ü The most significant deposits in Carajás were

discovered through geochemistry or magnetometric survey. The possibility of discoveries of blind non-magnetic IOCGs is real.

ü Au-Cu occurrences hosted in subvolcanic felsic

rocks and associated to propylitic and phyllic alteration have been identified at AFMP without however having been adequately drilled.

ü New discoveries of IOCG deposits will certainly

occur particularly when more detailed works will be developed in the areas where the presence of BIF masks possible magnetic responses of the IOCG.

ü Almost all the gold deposits in Brazil have been

so far discovered by gold “garimpeiros” or simple geochemical sampling. Little exploration on scientific grounds has been applied. Gold, goldcopper and polymetallic sulfide deposits have been discovered at AFMP, coeval with the volcanic-plutonic rocks dated between 1.82 and 1.70 Ga. The main deposit is Aripuanã, with world-class Zn-Pb-Ag-Cu-Au at northern Mato Grosso State.

ü The development of small-size, high-grade Cu-Au

deposits, such as in progress by Avanco at Antas and Pedra Branca deposits, and by Tessarema Resources at Maravaia Project, represent an important development at CMP. ü There are possibilities for base metal discoveries

along the lateral variations of BIF levels. Possible sin-sedimentary faults with evidences of exhalative feeds have been found.

ü There is currently only one small gold mine

(Paraíba) in operation in the AFMP and one project under licensing (Aripuanã).

ü The mineralizing Cu-Au corridors extend the area

of the Carajás basin, mainly to the south into the Rio Maria Domain.

Seridó Tapajós

ü The Seridó Mineral Province (SMP) hosts

historical tungsten mines back to the 1940´s, some still in production, and more recently gold, iron ore, gemstones and kaolin mines.

ü The gold mineralization of Tapajós Gold Province

(TGP) has some characteristics similar to several other mineralized areas of Au-Cu around the world.

ü The SMP hosts over 700 skarn occurrences,

ü The TPG is essentially a siliceous large igneous

containing W-Mo (Brejuí, Bodó, Bonito, Malhada Limpa and Quixadá mines), gold (Itajubatiba mine) and gold with associated W-Mo-Bi-Te (Bonfim mine).

province with a magmatic system covering an 2 area of 480,000 km . The qz-sulphide-gold veins at Ta p a j ó s re p re s e nt t h e ro o t s o f t h e mineralizing processes with hundreds of calderas and volcanic edifices. High and low sulfidations are part of the mineral system.

ü The main tungsten deposits are: Brejuí containing

11 Mt of WO3 (remaining 5.5 Mt at 0.5-1.0% WO3), and Bodó containing 9 Mt at 2% of WO3.

ü About 700 tons of gold have already been

ü The potential for base metals associated to the

produced by prospectors (garimpeiros), mostly alluvial. The economic potential of the area is underestimated. Little exploration on scientific grounds has been applied at the TGP.

skarns is still open, even with the presence of massive sulfide lenses associated to some tungsten mineralization. ü The São Francisco deposit, in licensing process by

ü The main deposits already defined at TGP are

Crusader Resources, contains 1.61 Mt of Proven + Probable Reserves and a total of 2.43 Mt in allc a t e g o r i e s r e s o u r c e s ( h t t p : / / w w w. crusaderresources.com/projects/borboremagold/, 19/02/2017).

Tocantinzinho (3.9 MOz Au reserves and resources), São Jorge (1,58 MOz Au), Coringa (913 KOz Au), Palito (668 KOz Au) and Boa Vista (336 KOz Au).

iii

ü Mineral exploration at SMP has been very

limited until now and focused mainly on tungsten. The discovery of Mesoarchean volcano-sedimentary sequences open opportunities for gold and base metals.

Gurupi

Northwest Ceará ü The geology of NW Ceará State comprises a

metasedimentary sequence with potential for SEDEX-type deposits, formed on a passive continental margin between 800-750 Ma and deformed during the Brasiliano/Panafrican orogeny. ü A series of NE-SW shear zones, with more than

200 km of extension, hosts distinct deposits and mineral occurrences, especially of copper, lead, zinc, manganese and iron.

ü São Luis cratonic fragment represents an

extension of the West Africa Craton that remained in South America after the Atlantic break-up.

ü Three main Cu-Pb-Zn targets are known: Uruoca

Target (Figure 05), Pedra Verde Mine and Serra de São José Target.

ü T h e C h e ga Tu d o a n d I ga ra p é d e A re i a

formations can be compared to its African analogues from the Ashanti Belt, the Sefwi and Tarkwan Groups, respectively, which host giant ore deposits and have a total endowment of ca. 125 MOz of gold.

ü Geophysical anomalies indicate potential for

copper unknown mineralization, including underneath the Silurian sediments of the Parnaíba Basin.

ü The Tentugal shear zone and its gold trends

extends for more than 100 km along strike and is estimated to continue to the north under Cambrian-Phanerozoic cover. The similarity between the mineralization of the Tentugal shear zone and the Birimian mineralization is particularly evident in terms of host rocks, mineralizing processes and tectonic control. ü New targets have been revealed by CPRM on

the Predictive Map of Prospectivity of Gurupi Belt, based on the geological, geophysical and geochemical database available at no cost at GEOBANK (http://geobank.cprm.gov.br/), associated to both first-and second-order structures, as well as to the extension of those structures under sedimentary cover.

Nova Brasilândia ü The Nova Brasilândia Group, at Rondônia State,

western Brazil, hosts recently discovered polymetallic sulfide mineralization (Zn-Cu-PbAg-Au) associated to a meta-sedimentary sequence named Migrantinópolis Formation. ü Geophysical data suggests that the sedimentary

sequence is continuous for at least 500 km in the E-W direction, with the eastern area covered by Cretaceous sediments and the western portion covered by Quaternary sediments. ü The polymetallic occurrences are 5 to 40 m thick

and 0.3 to 3 km long, and characterized by strongly oxidized massive and disseminated sulfide zones (gossans at surface), iron oxide veinlets and stockworks, siliceous breccia and quartz veins.

ü Four main deposits with resources already

defined are known at Gurupi belt and São Luís cratonic fragment, together dozens of other d e p o s i t s st i l l b e i n g ex p l o re d . C u r re nt resources for the main deposits are 6.1 MOz Au. The only operation in the area is the Aurizona gold mine owned by Trek Mining.

ü Most of the sulfide rich zones occur aligned to a

>50 km long magnetic lineament, interpreted as a sinistral transpressional fault. Other parallel lineaments represent open potential for future exploration programs. ü No deep exploration has yet to be carried out,

re p re s e nt i n g a n o t h e r o p p o r t u n i t y fo r exploration.

Geotectonic Setting of Brazilian Mineral Deposits Noevaldo Teixeira, Leonardo B. L. Lopes, Anderson D. R. da Silva.

Brazil is a major world producer of mineral commodi es such as Fe, Nb, Au, Cu, Zn, Mn, diamonds, Sn, Cr, Ta, and P2O5, which are mainly originated from two world-class mineral provinces: Carajás (State of Pará) and Quadrilátero Ferrífero (QF, State of Minas Gerais). The main deposits and tectonic se ngs per region of Brazil are discussed below. The eastern part of the Brazilian territory is mainly formed by Archean and Paleoprotherozoic

con nental arcs derived from subduc on processes remains fragile and lacks complete ﬁeld evidence (e.g. oceanic crust, ophiolites, sutures, paired metamorphic belts and tectonic vergence). Furthermore, there is a predominance of extensional structures and bimodal magma sm which are be er explained by underpla ng processes induced by mantle plumes (e.g. Uatumã, Parauari). The Brazilian metallogenic se ng results from two geodynamic processes including subduc on of the oceanic lithosphere and interac on of a mantle plume head with the con nental lithospheric keel. The eastern por on of Brazil (São Francisco Craton)

Carajás Province

Ty p e s o f D e p o s i t s

Algoma type (Fe) Superior Lake type (Fe) Rapitan type (Fe-Mn) Oolitic ironstone (Fe) Carbonatite-alkaline complexes (Ba-P-Nb-REE-Ti-U) Layered mafic-ultramafic complexes (Cr-Ni-PGE-Ti-V) Lode (Au-Cu-Pb-Zn) Orogenic (Au) Paleoplacer (Au-U) Porphyry (Cu-Au-Mo) Intrusion Related (Au-Cu-Mo-U) Epithermal (Au-Cu-Pb-Zn) Greisen (Sn-REE) VHMS (Pb-Zn-Cu-Au) IOCG (Cu, Au) Skarn (Au-W) SEDEX (Pb-Zn-Ag-Cu-Ba) MVT Irish Type (Pb-Zn)

Borborema

Maroni-Itacaiúnas Mobile Belt

. .

Au, W, Fe-Ti, P-U

Sergipano Belt

2.20-1.95 Ga

0.85-0.60 Ga

Cr, Ni

Au, Mn, Cr

Au-S-W Iron Quadrangle

Uatumã FLIP

Fe,Mn,Cu-Au, PGE-NI, Sn

2.05 - 1.87 Ga

Araguaia Belt Au-Cu, Ni, Pb Zn, Zn-Cu, P

3.1 Ga

Fe, Mn, Au

LEGEND

Phanerozoic cover Mobile belts (0.7-1.0 ga) Proterozoic sedimentary cover Cratons

Au, Mn

S.Francisco Craton

Amazonas Craton

Sedimentary deposits (Ba-Cu-Mn-P) Evaporites (K-Gypsum-Salt) Secondary Deposits (REE-Ti-Zr) Supergenic (Bauxite-Kaolin-Au-Mn-Ni) Primary Diamond Deposits Secondary Diamond Deposits

Paraguai Belt Paraná Craton

Brasília Belt

0.9 Ga Ma

Figure 01 - Map with a loca on of the main mineral deposits of Brazil.

cratonic nuclei that are surrounded by Neoproterozoic mobile belts. This old terrains are covered by Phanerozoic intracratonic basins making up an important part of the Gondwana paleocon nent (Cordani et al., 2000) Most of these belts were orogens built up by ri ing, ocean ﬂoor forma on, subduc on related volcanic arcs and collision processes (e.g. Brasília, Araguaia belts, Borborema Province). The Amazonian region (Central Brazil and Guianas shields) has a diﬀerent setup where the cratonic nuclei are progressively surrounded by younger terrains for which the geotectonic se ng is s ll debated and the Neoproterozoic records are scarce. The assump on of evolu onary models involving island and/or

Figure 02 - The figure shows the disrup on of the cratonic crust in the central region of Brazil at the beginning of Brazilian orogenic belt forma on. The disrup on of con nent by plume impact and ocean floor forma on exert major influence on mantle dynamics and on the Brazilian neoproterozoic mineral deposits forma on.

was surrounded by the Neoproterozoic Brazilian orogenies that were built up by the subduc on of the oceanic crust. This region hosts mineral deposits such as sedimentary exhala ve (SEDEX), porphyry copper, podiform chromite, volcanogenic massive sulﬁdes (VMS), and orogenic gold. The origin of these deposits is linked to asthenospheric fer liza on caused by the dehydra on of the subduc ng slab with release and interac on with pelagic sediments. On the other hand, on the edge

of the Archean Amazonian Craton (Sub-Con nental Lithosphere Mantle - SCLM) intense magma sm occurred during plume-related ri ing and extensional tectonics, without, however, advancing to an open ocean stage. In the Carajás Mineral Province, wich is located in the Amazon Craton, iron oxide copper-gold (IOCG deposits), n (Sn), banded iron forma ons (BIF's) and reef Ni-PGE deposits formed predominantly by the underpla ng-driven tholeii c magma sm, with strong interac on of mantle-derived hydrothermal ﬂuids mantle thermal instabili es likely linked to a mantle plume seem to have played a major role in the magma produc on and hydrothermal ﬂuids in the edge of the Amazonian Craton. (Teixeira et. al., 2009).

Plume Ore Deposit Related The Carajás ri (2.7 Ga) was formed on the edge of an Archean subcon nental lithosphere keel (Amazonian Craton). Three main ore-forming ages are recognized in Carajas : 1) The plume stage (or decompression mel ng stage) at ca. 2.7 Ga crea ng supergiant exhala ve sedimentary biochemical iron deposits ( Carajás Forma on with a total of 18 billon @ 60-67% Fe), exhala ve Cu-Au-Zn (Pojuca deposit) related to volcano-sedimentary sequences and Atype granite intrusion (2.7 Ga), and finally minor PGE-Ni reef deposits in tholeii c mafic-ultramafic layered intrusions (Luanga deposit); 2) the metasoma zed mantle fluids stage at ca. 2.5 Ga, concentrated along deep transtensional faults, with IOCG deposits such as Salobo, Alemão, and Sequeirinho (total resources for the order of 2500 Mt at 1% Cu and 0,5 g/t Au; Teixeira et al., 2010). The Serra Pelada Au-PGE deposit with 110 Ton of Au doesn´t have a consensus gene c model. 3) The remelted hydrothermal underpla ng stage at ca. 1.8 Ga, produced Cu-(Au-Mo-W-Sn) greisen (Breves deposit) and Cu-Au-Mo-F (Gameleira deposit) vein deposits associated with A-type granites (Teixeira et. al., 2009) The central por on of the Amazonian Craton, especially the Juruena and Tapajós provinces, encompasses extensive areas of alluvial and primary gold deposits (e.g. Tocan zinho with 49 Mt at 1,25 g/t Au, Juruena with 1.3 Mt at 5,6 g/t Au, Palito with 2.1 Mt at 5,85 g/t Au and 0,27% Cu, X1 with 8.5 Mt at 1,35 g/t Au and 4,6 g/t Au, Batalha, Paraíba, etc.). The primary mineraliza on occurs mainly in granitehosted quartz veins and resulted from magma c fluid interac on causing (a) phyllic altera on in the

host rocks. Recently, they are classified as porphyry and epithermal systems, gene cally linked to the subduc on-related hydrothermal systems (Assis et al., 2015; Juliani et al., 2014). We consider that the major gold deposits in these two regions are associated with intraplate bimodal igneous assemblages (Uatumã-Parauari, Teles Pires LIP's). The subvolcanic and volcanic gold mineraliza on styles are related to intraplate magma sm (plumerelated?) on the edge of the SCLM (Amazon Craton). The groups Araí, Chapada Diaman na and Espinhaço in São Francisco craton were all deposited in an intracon nental ri , during the Statherian period, host Sn deposits associated with greisens. In addi on, Au in veins that cut dal-flats and organic lagoon sedimentary facies are also found. Nonetheless, the Mesoproterozoic ri s in the northern por on of the Mato Grosso and Rondônia States host the greatest poten al for the discovery of new Pb-Zn-Cu SEDEX) and VMS, like the worldclass Aripuanã deposit (34 Mt at 4.27% Zn, 1.50% Pb, 0.29% Cu, 0.30 g/t Au and 37.39g/t Ag; Votoran m Metais, 2011) and the Nova Brasilândia deposit respec vely, both being explored. The presence of extensive translithospheric fault zones throughout the Brazilian shield favored the intrusion, during the Cretaceous period, of several alkaline bodies (e.g. Poxoréu, Iporá, Alto Paranaíba, Serra do Mar, Caja , Jacupiranga, Catalão, Araxá), some of them alkali-ultramafic and carbona tes hos ng supergiant Nb deposits and large P2O5 deposits a er lateri c weathering. Brazilian kimberlites occur mostly along pericratonic mobile belts with thinned or metasoma zed lithospheric keel. However, there are kimberlites in the São Francisco Craton where it is s ll possible to recons tute, via deep seismic and thermobarometry of mantle xenocrysts, a depleted harzburgi c keel of >150-km thick as in the case of kimberlites of the Nordes na region, State of Bahia (Braúna 3, the first kimberlite-hosted diamond mine in Brazil). In the Amazonian Craton mineralized kimberlites are found both in the depleted harzburgi c keel (State of Rondônia) and in mobile belts without lithosphere root. This also seems to apply to the kimberli c Juína Province (State of Mato Grosso) with Transi on Zone, diamonds thus jus fying the total absence of sub-calcic garnets or Cr-rich spinel as indicators. Un l now there are no robust scien fic to explain the source of several tens of alluvial diamonds over 100 carats from

Au-Cu-Zn

Zn-Pb-Cu-Au

2,03 Ga

Fe-Mn-Au-Cu-Ni

TTG 3.30 Ga Underplate Metassome 70-90 Km

Cr-Ni

2,70 Ga

P-Ti

Mn-Au-Cr

2.20 Ga

Ti, P, CI, CO2, ETR U, K, Na, Zr, Ca, Ba, Cu, Nb, Ni, Co, EGP, Fe, SIE, Alto Redox

750 Ma

Metassome 120 - 200 Km

280 Ma Plumes

90 Ma

1.8 Ga 2.5 Ga 2.7 Ga

Astenosphere

Figure 03 - Schema c sec on along the Amazon craton. The figure shows the wide predominance of thermal anomalies (adiaba c melts or plumes), as major magmas and hydrothermal fluids. Some units were represented without deforma on effect

Douradinho, Santo Inácio, and Paranaíba, making the diamond presence from the Triângulo Mineiro in the State of Minas Gerais (Coromandel, Alto Paranaíba) the next exploratory challenge.

northeast region of Brazil, the end of the Brazilian Orogeny (Seridó foreland basin) is marked by the emplacement of large grani c plutons mineralized with (in) Au and W. This magma sm was generated by the delamina on of the lithospheric mantle producing high heat ﬂow by the invasion of asthenospheric material into the base of the con nental crust and genera ng W and Au mineraliza ons (Ganade et. al. 2013)

Subduc on Ore Deposit Related In the central por on of Brazil, Cu-Au deposits (Chapada region) occur in a Neoproterozoic subduc on-related magma c arc in Brasília Orogenic Belt. These porphyry Cu-Au deposits (420.94 Mt at 0,29% Cu and 479.84 Mt at 0.25 g/t Au; Oliveira et al., 2016) were metamorphosed to amphibolite facies and strongly folded. Brazil has favorable geological environments for volcanogenic deposits linked to and volcanic ri s and paleovolcanic arcs as Palmeirópolis, Bom Jardim, Vale do Ribeira, Salobro, and Cabaçal. Behind Brasilia Arc in the opposite passive con nental margin, the metasedimentary sequence is thrusted over in the edge of São Francisco Craton. This sequence host Morro do Ouro deposit, Zn (Vazante deposit) and PbZn (Morro Agudo deposit). Morro do Ouro is a worldclass gold deposit (600t) that was possibly formed by the biological accumula on of gold in a back-reef environment before being remobilized by metamorphic ﬂuids during thrus ng. Vazante and Morro Agudo (18.3 Mt at 5,08% Zn and 1,75% Pb; Neves, 2011) deposits were formed in an exhala ve se ng controlled by faults and diagenesis of a backreef facies respec vely. Both deposits are hosted in Neoprotherozoic carbonate rocks that were deformed during the Brasiliano Orogeny. In the

Ore Deposits Related to Plumes and Subduc ons It is possible that during the evolu on of the TTGGreenstone belts subduc ons and plumes have acted together (Arnt and Nisbet 1982). Brazil has a significant extension of TTG-Greenstone belts. In the Archean Rio das Velhas greenstone belt (Iron Quadrangle) there are thick piles of metakoma ites basal c flows, felsic metavulcanics, BIF and metavocanoclas cs. The gold deposits of the Rio das Velhas greenstone belt, such as Morro Velho, Cuiabá, and São Bento (>470 t Au, >180 t Au and São Bento >80 t Au, respec vely; Abreu et al. 1988), are hosted in BIF's that were sulfurized by metamorphic fluids during regional deforma on and low-grade metamorphism (greenschist facies). The giant iron ore deposits of the Minas Group occur in exhala ve chemical sediments that were deposited on TTGgreenstone belts substratum (bedrock) in a passive con nental margin. Numerous other Archean and Paleoproterozoic greenstone belts in Brazil contain orogenic gold deposits (e.g. Crixás, Itapicuru,

Cu-Au

Ni-Cu Au

Zn-Cu

3 2 3.0 Ga

Ni 4

P-Nb Di Cr Au Zn

Au-U Pb-Cu Pb-Zn Au Au Fe-Mn Au-Di Mg UPb-Zn Cr Au Cr Cu Di 11

10 9

12 3,4Ga

1 900-800 Ma

13 2.4 Ga

21 20 19 2,9 Ga

17 18

14 15 16

23 24

2,6 Ga

1 - Chapada, 2 - Crixás, 3 – Palmeirópolis, 4 - Barro Alto-Niquelândia, 5 - Americano do Brasil, 6 - Morro do Ouro, 7 - Moro Agudo, 8 - Vazante, 9 - Catalão, 10 - Alto Paranaíba, 11 - Januária, 12 - Quadrilátero-Ferrífero, 13 - Rio das Velhas, 14 - Espinhaço, 15 - Brumado, 16 - Lagoa Real-, 17 - Redenção, 18 - Medrado, 19 - Campo Formoso, 20 - Jacobina, 21 - Novo Mundo, 22 - Caraíba, 23 - F. Brasileiro, 24 - Nordes na. Figure 04 - Schema c sec on along the São Francisco craton. It shows the wide predominance of thermal anomalies (adiaba c melts or plumes), leading to the forma on of magmas and hydrothermal fluids. Unlike Amazon craton, the mineralizing process comes from the interac on of the oceanic slabs with asthenospheric wedge, genera ng hydrothermal fluids. Some units were represented without deforma on effect.

Cipoeiro, Aurizona, Chega Tudo, Amapari, Salamangoni, Volta Grande) occurring par cularly on terranes of the Amazonian Craton and São Francisco Craton. Moreover, Brazil has a diversified and significant number of mafic-ultramafic bodies formed by plumes or mantelic adiaba c fusions in subduc on zones. The mafic-ultramafic complex occur in five main geotectonic se ngs and have associated deposits: 1) TTG terranes and greenstone belts; 2) intracratonic granuli c belts and orogenic belts roots; 3) ensialic ri s; 4) subduc on zones in Neoproterozoic orogenic belts; and 5) intracratonic basins. The most significant deposits are: a) Ni-CuPb-Zn Cu Cu 1 2 3

U-Pb

PGE deposits in reefs of intracratonic layered complexes (e.g. Luanga); b) Ni-Cu deposits in Archean koma ite lava channels (e.g. Fortaleza de Minas); c) dissemina ons in magma c conduits controlled by translithospheric fault (e.g. Limoeiro, and Caraíba with a total of 42 Mt at 1,82 % Cu; Dardenne et al., 2001); d) synorogenic hydrated magma c chamber (e.g. Americano do Brasil); e) dissemina ons in diﬀeren ated magma c chamber (e.g. Mirabela); f) podiform chromite deposits in residual harzburgites (e.g. Morro Feio, Qua puru); g) stra form chromi te in cumulate on the bo om of layered complexes (Bacuri); h) Fe-Ti-V-PGE deposits in magne te-rich layers between gabbro

Cr-PGE 4

Au 6

Li-Ta pegma tes Fe -Ti W Au Fe Au 8 9 7

Fe -Ti

610-650 Ma 2.2 Ga

2.2 Ga 2.7-3.0 Ga

1 - Martinopole, 2 - Pedra Verde, 3 - Jaibaras, 4 - Itataia, 5 - Tróia, 6 - São Fernando, 7 - Saquinho, 8 -Brejuí, 9 - São Francisco, 10 - Itapetim.

Modiﬁed from Araújo et al., (2013)

Figure 05 - Schema c proﬁle of NE region, showing the mechanical erosion delamina on of lithospheric mantle. High heat ﬂow produces huge felsic plutonism a er con nental collision of the Neoproterozoic Brazilian fold belt.

and piroxenite (Maracás); and h) lateri c nickel (e.g. Niquelândia, Barro Alto, Vermelho, and OnçaPuma). Therefore, Brazilian mineral deposits appear to be associated with episodes of craton fragmenta on by plume impact and periods of amalgama on with ocean ﬂoor consump on by mantle sinking.

References ABREU, A. S.; DINIZ H. B.; PRADO, M. G. B.; SANTOS, S. P. A mina de ouro de São Bento, Santa Bárbara, Minas Gerais. In: SCHOBBENHAUS, C.; COELHO, C. E. S. (coord.). Principais Depósitos Minerais do Brasil. Brasília: DNPM, 1988. V. III, p. 393-411.

JULIANI, Caetano et al. Metalogênese da Província Tapajós. In: SILVA, Maria da Gloria da (Org.) et al. Metalogênese das províncias tectônicas brasileiras. Belo Horizonte: CPRM, 2014. P.229-268. NEVES, Luiz Paniago. Caracterís cas descri vas e gené cas do depósito de Zn-Pb Morro Agudo, Grupo Vazante. 2011. 89 f., il. Dissertação (Mestrado em Geologia) – Universidade de Brasília, Brasília, 2011.

ASSIS, R. R. Depósitos auríferos associados ao magma smo félsico da Província de Alta Floresta (MT), Craton Amazônico: Litogeoquímica, idade das mineralizações e fonte dos ﬂuidos. 2015. 363 p. Tese (Doutorado) – Ins tuto de Geociências, Universidade de Campinas, Campinas, 2015.

OLIVEIRA, C. G.; OLIVEIRA, F. B.; DELLA GIUSTINA, M. E. S.; MARQUES, G. C.; DANTAS, E. L.; PIMENTEL, M. M.; BUHN, B. M. The Chapada Cu–Au deposit, Mara Rosa magma c arc, Central Brazil: Constraints on the metallogenesis of a Neoproterozoic large porphyry-type deposit. Ore Geology Reviews, v.72, Part 1, p.121, Jan. 2016.

ARNDT, N. T., NISBET, E. G. Koma ites. London: George Allen & Unwin, 1982. 526p. BRITO NEVES, B. B; FUCK, R. A.; PIMENTEL, M. M. The Brasiliano collage in South America: a review. São Paulo, Brazilian Journal of Geology, v.44, n.3, p.493-518, July/Sept. 2014.

TEIXEIRA, J. B. G.; LINDENMAYER, Z. G.; SILVA, M. G. Depósitos de Óxidos de FerroCobre-Ouro de Carajás. In: BRITO, R. S. C.; SILVA, M. G.; KUYUMIJIAN, R. M. (org). Modelos de depósitos de cobre no Brasil e sua resposta ao intemperismo. Brasília: CPRM, 2010. P.15-48.

COMPANHIA VALE DO RIO DOCE. Carajas Iron Ore Mine, Brazil. Disponível em: www.mining-technology.com/projects/carajas Acesso em: 13 fev. 2017.

TEIXEIRA N.A., FREITAS-SILVA F.H., CORRÊA C.R.A., ROSA, W.D., OLIVEIRA J.K.M. DE, ROSENDO O.S.C., PINHEIRO JR. V. 2009. Evolução geológica e mineralizações primárias da Província Mineral de Carajás. III Simp. Bras. Metalogenia, Gramado, RS.

CORDANI, U. G.; MILANI, E. J.; THOMAZ FILHO, A.; CAMPOS, D. A.; (Org.). Tectonic Evolu on of South America. 1ed. Rio de Janeiro: 31 Interna onal Geological Congress, 2000 v. único, p. 750-850. DARDENNE, M. A.; SCHOBBENHAUS, C. (org). Metalogênese do Brasil. Brasília: UnB: CPRM, 2001. P.114-115.

VOTORANTIM METAIS. Aripuanã. Disponível em: <h p://www.vmetais.com.br/enUS/Negocios/ExploracaoMineral/PrincipaisProjetos/Pages/Aripuana.aspx>. Acesso em: 13 fev. 2017.

GANADE DE ARAUJO, C. E.; WEINBERG, R. F.; CORDANI, U. G. Extruding the Borborema Province (NE-Brazil): a two-stage Neoproterozoic collision process. Terra Nova, v. 26, p. 01-12, 2013.

Pirajno F., and Santosh M. Mantle plumes, supercon nents, intracon nental ri ing mineral systems. Precambrian Research: 259 (2015) 243-261

Carajás Project Ulisses Costa, Desaix Silva, Jaime Barbosa, Junny Oliveira, Rodolfo Reis, Raphael Araújo, Marcelo Januário

Considering a very regional picture of the southeastern part of the Amazon Craton, the region is characterized by the presence of important polymetallic deposits, which can be grouped into three main types, according to their geotectonic se ngs: (i) Archean TTG (tonalite-trondhjemitegranites) and greenstone belts that host orogenic gold deposits (e.g. Rio Maria Province); (ii) Archean polymetallic subcon nental lithospheric mantle (SCLM) ri s that host world-class Fe, Cu-Au (IOCG), Ni (IONC and laterite), Au-PGE deposits (e.g. Carajás Mineral Province); and (iii) Proterozoic epithermal and quartz veins gold deposits in the Tapajós area. The Carajás Mineral Province (CMP), formed from 2.76 to 2.55 Ga, is located in the eastern por on of Amazon Craton, northern Brazil. It is considered one of the most important mining areas worldwide, containing several world-class IOCG, nickel, PGE, iron ore and manganese deposits (Figure 1).

The large amount of geological data already published concerning the Carajás Mineral Province, associated with recent acquired airborne radiometric (Figure 2), magne c (Figure 3) and gravity data and remote sensing images, comprise t h e b a s i s fo r t h e G e o p hys i ca l - G e o l o g i ca l interpreta on maps in progress by CPRM. All the data has free access and is available at CPRM website (h p://geobank.cprm.gov.br/). The Mesoarchean Carajás basement assemblage consists of TTG granite-gneiss-migma te (Xingu Complex), mafic granulites (Xicrin Cateté Orthogranulite), and greenstone belts (Sequeirinho, Selva and Rio Novo groups), dated at around 3.073.0 Ga (Pidgeon et al., 2000; Moreto et al. 2011; Silva 2014). The Neoarchean Carajás basin comprises metavolcano-sedimentary units (2.76 Ga., Itacaiúnas Supergroup; DOCEGEO, 1988) which host the main Fe and Cu-Au deposits. The succession consists, from the base to the top, of bimodal maficfelsic metavolcanic rocks, BIFs (hos ng giant iron ore deposits), metapyroclas c and metasedimentary rocks, deposited in a marine ri environment (Gibbs et al., 1986). The metamorphism ranges from low greenschist to amphibolite facies. Coeval maficultramafic layered complexes (2.76 Ga, e.g. Luanga Complex; Machado et al., 1991) hos ng PGE-Ni deposits, and syn-tectonic alkaline to sub-alkaline granites (2.76-2.70 Ga, e.g. Estrela and Gelado granites; Barbosa et al., 2001) are widespread in the Carajás basin, as well as 2.65 Ga gabbroic dikes and

The Geological Survey of Brazil currently runs three work programs dedicated to oﬀer basic geological data and knowledge to investors: (i) Geophysicalgeological integra on maps of ten 1:100,000 sheets; (ii) Detailed mapping along the Cinzento Lineament, aimed at establishing the main regional controls of the copper deposits located in this transcurrent system; (Iii) Detailed mapping of the Mn deposits, in order to deﬁne their stra graphic and faciological controls. In addi on, detail mapping at 1:50,000 scale is being carried out for the volcanosedimentary sequences, including the Aquiri unit.

Jacareacanga

Maroni - Itacaiúnas Mobile Belt Au, Mn Volta Grande

Fe, Mn, Cu-Au, Au-PGE, Ni, Sn Carajás Ri

BIF

Uatamã Felsic LIP

Au, Ni

1.88 Ga

Au, Sn 2,76 Ga

Uatumã FLIP

Itacaiúnas SuperGroup

Cuiú-Cuiú Complex

Araguaia Orogen Cr-Ni

Buri rama Rio Novo

2.70 Ga

2.15 Ga

Archean Primi ve Crust 2.00-1.88 Ga

Felsic Magma 2.10 Ga

Underplate Con nental lithospheric keel

Lithosphere

Lithosphere Astenosphere

Figure 01 - Geotectonic se ng of Carajás basin, interpreted as a ri or a strike slip basin. It presents a typical sigmoid structure controlled by transcurrent shear zones (Araujo et al., 1991). The basement of the Carajás basin is composed of TTG-greenstone belt. The eastern border of Amazon craton is marked by Bacajá fold belt (2.2 Ga) and the obduc on of Neoproterozoic Araguaia oﬁolite. The western limit was ri ed in huge exten onal event in the Paleoproterozoic (Tapajós region).

eTh

Figure 02 - Interpreta on of Ternary Map (K, eTh and eU) and correla on with known geological features.

aul

F osa

teri

Mis

aul

F less

a McC CarapanĂŁ

Figure 03 - Magne c interpreta on of lineaments from the magne c products of the Total Magne c Intensity (Ex: First Deriva ve of Magne c Anomaly Field).

sills. A Paleoproterozoic low-grade sedimentary sequence overlies the Itacaiúnas Supergroup, comprising ﬂuvial to shallow marine sandstones and siltstones (Águas Claras Forma on; Nogueira et al., 1995) which contain manganese deposits (Azul 0

Mine). Paleoproterozoic A-type granites (1.88 Ga; Dall'Agnol et al., 2005) outcrop throughout the Carajás region, as well as maﬁc and felsic NE and NW dykes (Figures 4, 5, 6 and 7).

52 30’W

51 30’W

50 30’W

49 30’W

Cu, Au Cu, Au Cu, Au Au, Cu

sF au

Au, Pt, Pd

Cu, Au

Cu, Au Fe

já

Parauapebas

Fe Mn

Cu, Au ault nã F

Rio

Cara

Xin gu

Fe Cu

Cu, Au 0

6 30’S

Fe São Félix do Xingu

Canaã dos Carajás

Tucumã

Água Azul

Cu, Co Au

W, Sn

30km 0

Cities Roads Rivers Railroad

Major lineaments Deposits Inactive mines Active mines (active)

TECTONOSTRATIGRAPHIC ASSEMBLAGES Mesoarchean TTG Suites Mafic granulites Greenstone belts TTG orthogneisses, migmatites and granitoids

Neoproterozoic Araguaia belt Paleoproterozoic (Orosirian) A-type anorogenic intrusions Rift basin (bimodal volcanic rocks) Rift basin (sedimentary rocks) Foreland basin

Paleoproterozoic (Rhyacian) Calc-Alkaline orogenic intrusions Intracratonic basin Neoarchean Alkaline to subalkaline intrusions Mafic-ultramafic layered intrusions Volcanosedimentary sequences

Figure 04 - Geological map of Carajás Mineral Province. Águas Claras Forma on

Pojuca

Pb-Pb (Z and WR): 1.88 Ga 1,87-2,0 Ga (DZ): 2,87 -3,05 Ga

2.76 Ga

U-Pb (Z): 2,65-2,70 Ga

(DZ) 2.87-3.05 Ga

Granites

Rhyolite Black Shale BIF Carajás Fm U-Pb (Z): 2,76 ± 2 Ga IZ: 2,85 to 3,42 Ga

TTG-Greenstone

Figure 05 - Deposi onal environment of Carajás Province. It presents high variability due to the strong tectonic compartmenta on of the ri or strike-slip basin. Black shale Silstones, sandstones, conglomerates shales, breccias

Sandstone Águas Claras Forma on

Black shale,sandstones Breccias Red Siltites Dolomites

Mafic lavas, BIF, Tuffs, metapelites, andesites, turbidites.

Salobo, Pojuca, Igarapé-Bahia Groups

Águas Claras Forma on

Mn Shale Red Sandstone Conglomerates

Basaltic flows Rhyolite

Basaltic flows Black Shale

Grão Pará Group

Mod. from Teixeira et al., 2010

Basaltic flows

Metapiroclastics Jaspilites Greenstone belts: Komatiites, basalts, BIF, piroclastic and sedimentary rocks

Xingu Complex (>2,86 Ga)

Figure 06 - Estratigrafic Column from Central Carajás

BIF Luanga, Luanga Sul Maﬁc-ultramaﬁc complex Greenstone belts: Koma ites, basalts, BIF, piroclas c and sedimentary rocks

Figure 07 - Estratigrafic Column from Serra Pelada

Grão Pará Group (2,76 Ga)

Xingu Complex (>2,86 Ga)

Recently, new geochronological data provided by detrital zircons shows that the Aquiri Unit has a maximum deposi onal age around 2.86 Ga (Figures 8 and 9). This age does not deﬁne whether the metavolcano- sedimentary sequence of Aquiri Unit is part of the greenstone belt or is related to the Itacaiúnas Supergroup. The maximum deposi onal age of the Água Claras Forma on deﬁned by detrital zircons is 3.24 Ga (Figure 10), highli ng the absence of Transamazonic zircon ages.

Despite of the mineral importance of the area, basic geological and geochronological knowledge is s ll scarce. The deposi onal environment of Carajás presents high variability due to the strong tectonic compartmenta on of the ri or strike-slip basin. There is no single stra graphic column that is valid for the en re Carajás region. In addi on, the stra graphic units like Salobo, Igarápé Bahia, Pojuca were deﬁned based on drill holes observa on due to the absence of outcrops.

490000

470000

450000

9344000

STRATIGRAPHIC UNITS PALEOPROTEROZOIC

A-type granite

450

000

Gabbros

NEOARCHEAN

Metamafic rocks Sub-alkaline metagranites

Cateté Suite Pyroxenites, peridotites and gabbros l vgranites Undifferentiated

Metavolcano-sedimentary Sequences

Quartzites, schists and BIFs Metarenites, metapelites Quartzites Phyllites Schists and BIFs BIFs Phyllites and quartzites Metabasalts Salobo-Pojuca Formation (quartzites and metapelites) Parauapebas Formation (metabasalts)

Edileuza

932

9328000

Aquiri Group

Liberdade Group

800

56°W

52°W

48°W

2°N

BRASIL

AMAPÁ

2°S

AMAZONAS

MESOARCHEAN

PARÁ STATE

Basement assemblage

MARANHÃO

Vila Sassá Gneiss (orthogneisses and granulites) Nova Índia Gneiss (ortho and paragneisses) Xingu Complex (orthogneisses and migmatites)

6°S

BRASIL

6°S

Aquiri area

A TOCANTINS PI MATO GROSSO 56°W

52°W

490000

470000

48°W

Figure 8 Aquiri geological map. The western por on of Carajás has only maps at a scale of 1 / 250,000. The SGB-CPRM is currently developing a 1 / 50,000 scale mapping program of the volcanosedimentary sequences in this region (North of São Feliz), in order to separate the greenstones belts from the western con nuity of the Itacauinas Supergroup. Thereby, the limits of the Carajás Basin will be deﬁned more precisely.

Number

2941 10

3186

3395 4

3503

3200

3100

Idade

Águas Claras Formation

3271

3093

Relative probability

0 2700

3248

Aquiri Group

2868

Number

3500 207

Pb/

0 2500

3900

206

2900

3300

Idade

Pb (Ma)

Figure 9 Probability density plot of quartzite from the Aquiri Group (Detrital Zircon). The maximum deposi onal age is indicated by the youngest peak of 2868 Ma.

207

Pb/

3700

206

Pb (Ma)

Figure 10 Probability density plot of 207Pb/206Pb ages of detrital zircon from the Águas Claras Fm. The youngest peak of 3093 Ma indicates the maximum deposi onal age. Although 3 young crystals have been iden ﬁed, due to their small expression they are not considered sta s cally valid for the indica on of the deposi on limit.

Three main mantle-related mineralizing processes are recognized in the Carajás ri (Teixeira et al., 2009): (i) 2.76 Ga crustal exten on (plume or descompressional mafic underplate), resul ng in basal c and rhyoli c flows and giant hydrobiogenic volcanic-exala ve iron deposits (e.g. N4, S11D), minor disseminated volcanogenic Cu-Zn deposits (e.g. Pojuca), tholeii c mafic-ultramafic layered intrusions (Onça-Puma, Jacaré, Jacarezinho) with PGE-Ni reefs (e.g. Luanga) and IOCG deposits (e.g. Sequeirinho-Pista; Moreto et al., 2015); (ii) 2.612.55 Ga crustal exten on, decompression of the metassoma zed mantle, and forma on of satured (O-H-C-S-Cl-rich), blind metasoma c mantellic alkaline rocks and IOCG deposits (e.g. Salobo, Alemão); (iii) 1.88 Ga A-type granits refle ng a huge mantle plume event which reached all the central Amazonian Craton, producing in the Carajás Province Cu-(Au-Mo-W-Sn) greisens (e.g. Breves), Cu-Au-Mo-F intrusion related deposit (e.g. Gameleira), manganese deposits and the unusual Au-PGM Serra Pelada deposit, the last two correlated to the Águas Claras Forma on´s lowermost unit (Figure 10). Grainger et al. (2008) and Teixeira et al. (2009) considered that the metallogeny of the CMP is petrologically related to SCLM dynamics involved in ac ve ri se ng. Metamorphic-hydrothermal-magma c events, established at 2.70-2.55 Ga, contemporaneous with the reac va on of extensive regional shear zones, were important components for the Carajás metallogene c evolu on (Figure 11).

interbedded with the metabasalts of the Grão Pará Group, both part of the Itacaiúnas Supergroup. The Grão Pará Group crops out along the northern and southern ﬂanks of a synclinal structure, known as the Carajás syncline, with a major shear zone, known as the Carajás shear zone, along the axis of the fold. Vale, the largest mine operator at CMP, has recently launched the S11D world's largest iron ore mine, with capacity to produce 90 Mtpy. The total iron ore resources of the several known deposits exceed 20 billion tonnes, with grades over 65% Fe. The orebody thicknesses vary, in general, from 250 to 300 meters. Jaspilites cons tute the proto ore of the iron ore deposits of the CMP, being the weathering responsible for the so high grades. High-grade iron ore mineraliza on (> 65 % Fe) is made up of hard and so ores. The hard ores can be banded, massive and/or brecciated and are composed mainly by microplaty hema te. The so ores are very porous, discon nuous and tabular, friable and banded. The basal contact of high-grade iron ore is deﬁned by a hydrothermally altered basal c rock mainly composed of chlorite and microplaty hema te. (Silva, 2009). The mineraliza on is considered as vulcanogenic and the high grade por on is a primary feature related to the proximity of the exhala ve centers (Teixeira et al, 2009) (Figure 12) . The Carajás Mineral Province (CMP) is the second largest IOCG (Cu-Au) province in the world (Figure 1 3 ) . T h e I O CG d e p o s i t s d o n o t s h o w a ny stra graphic preference or lithological control, occurring in granites, metabasalts, metarhyolites a n d m eta s e d i m e nta r y ro c ks . T h e l eve l o f deforma on of the host rock varies greatly from cataclas c (milonite), as at Salobo, to weakly

CMP has one of the largest high grade iron ore deposits of the world. The iron ore deposits are hosted by the Carajás Iron Forma on, which occurs

Ni 1

Black Shale

Au-Mo-W-S Cu-Au-Mo-F 5 4

Cu-Zn Bacteria

BIF

Greywacke Compact Hema te N4, N5, ...S11D

IOCG

Águas Claras Na Sossego, Sequinho Cristalino

2.70 Ga U/Pb

Tholeii c Basalt

Gameleira

Granite 2.7 Ga

Salobo

Post-Ri Fase 7. Mn Sedimentary 8. Au-PGE Redox Sedimentary 4 and 5. Felsic Intrusion Related (1.80 Ga)

5. IOCG 9. PGE-Ni Reef

Reef

Manganês do Azul Fe K Ca

Maﬁc 2.7 Ga

Luanga

Serra Pelada Breves

Cordierite - Antoﬁlite

Hema za on Siliciﬁca on Carbonata on

Sin - Ri Fase (2.76 Ga) 1. IONC 2. Hydrobiogenic volcanic-exhala ve iron deposit 3. BIF host volcanogenic Cu-Zn

PGE-NI 9 Perido te Pyroxenite -Gabbro

Au-PGE 8

Bahia

Cu, Au, Mo, F

Jaspe

Mn 7

Layered maﬁc-ultramaﬁc intrusion 2,76 Ga Wirth et all., 1986

Mod. from Teixeira et al., 2009

Figure 11 - Types of mineraliza on in the Carajás Mineral Province.The Carajás Archean ri hosts a giant 200 x 100 ore system. The basin was filled up by con nental tholeii c basalts and rhyolites followed by BIF´s and vocanogenic sediments. The upper unit is dominantly composed by sedimentary rocks. Three main mineralizing mantle-related processes are recognized in Carajás ri . These processes involve magma c ac vity, exhala ve solu ons, hydrothermal fluids that were responsible for several different types of mineraliza on as shown in the figure.

Foto credits Vale

Figure 12 - Pit of the N-5 iron mine.

Figure 13 - Pit of the Sossego copper gold mine.

deformed rocks. The host lithologies, however, determine the style of the ore bodies. The more competent rocks show more veins and breccias and less subs tu on. The Cu-Au Salobo mine, in opera on since 2012, is one of Vale's most important opera ons and the largest copper mine in Brazil, producing 200,000 tonnes of copper concentrate per year. Salobo is the most deformed IOCG deposit at CMP, as it has been submi ed to Paleoproterozoic deforma on and metamorphism, which resulted in a strong structural control along E-W duc le-bri le shear zones with of high angle bends and jogs (Figure 14 and 15).

altera on. The depth of the metals deposi on and deposit forma on is cri cal to determine the hydrothermal associa on. The Salobo deposit represents the root of a hydrothermal system, while Alemão and Igarapé Bahia deposits are higher in the stra graphic sequence, been characterized by lower-temperature mineral associa ons. The deposits show schistosity and mineral linea on formed during the hydrothermal altera on process. Such features are explained as the ﬁnal part of the complex deforma on history of mineralized conduits (2.5 Ga) or by the eﬀect of later orogenies (Tavares, 2015). Carajás IOCG deposits contain stable isotopes typical of deeply formed magmas and/or mantle deriva on. The ore forming process included upward aqueous hypersaline, acidic and

Carajás IOCG shows strong calcic, iron and sodic

Buritirama Serra do Buritirama Buriti Madeira

GT-46 Salobo Liberdade

Furnas

Paulo Afonso

Breves

Serra Pelada

Gameleira Igarapé Bahia

Serra da lua Nova Serra do Jacaré

Águas Claras Estrela

Castanha Sequeirinho Sossego Puma

Bacia do Rio Xingu

Formiga Luanga Serra Leste

Mina do Azul

Igarapé Antônio Vicente

São Felix

Serra do Sereno

Carapanã

GT-34

Bacaba

Cristalino Visconde Brilasa Serra do Rabo Vermelho

Onça

Setor Biquinha

Fafá Alto do Rio Branco Sapucaia

Serra do Mocambo

Boa Esperança

Ourilândia do Norte

Bom Jardim

Mines

Mineral Deposits

Main structures

Figure 14 - Tectonic controls of IOCG mineralizations. Note the Carajás sigmoid in the central of the image. The mineralizing Cu-Au corridor extrapolates the area of the Carajás basin, mainly to the south into the Rio Maria Domain.

SW Elevação (m)

Elevação (m)

-1200

3D invesion of magnetization vector

-1200

-2400

Susceptibility 0km

15.3km

3D invesion of magnetization vector

0km

19.7km

Salobo’s Mine (Cu/Au) Plunge to NE

Target (Cu/Au) Plunge to SW

Elevação (m)

-1200

-2400

0km

12.8Km

3D invesion of magnetization vector

F Furnas Deposit (Cu/Au) Plunge to NE

Unconsolidated sediments Laterito Magmatism A-type Granite (1.88Ga) Meta-granite (2.74Ga) Carajás Extensional Basin Meta-sediments (biotite-garnet cordierite xist) Meta-sediments (quartz-xist) BIF and metavolcano-sedimentar Meta-volcanic and BIF Basement Gneisses and Migmatites

Cupper Iron Gold Amethyst Manganese

Transpressional Structures Compressional Structure Transtensional Structures Silicous

-51º

High

-5º 40'

-50º30'

Low

Lineament Density

-5º 50'

-50º00'

-6º

Active Mines Active Garimpo Inactive Garimpo Mineral Deposits Occurrences

Figure 15 - Results of the detail mapping along the Cinzento shear zone. There is an obvious rela onship between the intensity of the magne c lineaments and the mineralized areas.

oxidized ﬂuids interac ng with cooler and low salinity meteoric and/or basin ﬂuids, resul ng in the precipita on of the metals and forma on of the majority of the IOCG deposits in the Carajás Mineral Province (Monteiro at al, 2014) .

ﬁne-grained sandstones and conglomerates) of the Águas Claras Forma on . The sedimentary facies that hosts the primary manganese deposits of CMP are restricted to an oﬀshore zone, nearby the shoreface, and overlies thick turbidi c deposits rich in organic ma er (Figure 17).

The manganese is one of the most important mineral resource at CMP, with two world-class mines in opera on: The Azul mine, owned by Vale and in produc on since 1985 (Figure 16), and the Buri rama mine, owned by a Brazilian private group, Mineração Buri rama, and in opera on since 2002. In addi on, there are two other remarkable manganese deposits in the Province, both belonging to Vale and known as Serra do Sereno and Antônio Vicente. The sedimentary succession that contains the manganese in the Azul and Serra do Sereno areas was deposited in the same geological context, and is represented by a siliciclas c sequence (mudstones, red siltstones, manganesiferous pelites, coarse to

Foto credits Vale

Figure 16 - Pit of the Azul manganese mine.

The metasedimentary sequences (quartzite, banded iron forma on, banded manganesiferous) registered in the Serra da Buri rama and Antônio Vicente regions, in turn, evolved in neoarchean mes, and were probably deposited along with volcanic episodes, in ri systems. Besides its sedimentary origin, all the known

Coastal Sandstone

manganese deposits are characterized by superposed tectonic/hydrothermal processes that remobilize and precipitate the manganese along the major structures, mostly into fault systems. This type of occurrence forms the main economically viable zones. Supergenic enrichment is the important manganese concentra on processes (Figure 18).

Progradation of sedimentary units and redox line migration

Mina do Azul Serra do Sereno

Tempestite Algae Carbonate

Carbonate Bank

Siltite with Mn-oxide

Mn Mn Black Shale

OXIDIZED ANOXIC

Buri rama BIF

Antônio Vicente

Compact Hema te Altera on Zone Ri Sequence

2.1 Ga

TTG - Grestone Belt Águas Claras Forma on Grão Pará Group Mod. from Teixeira et al., 2009

Figure 17 - The Azul and Sereno Mn deposits are located in oﬀshore zone, nearby the shoreface overlying thick and rich organic turbidite of the Águas Claras Forma on. Otherwise, the Buri rama Mn deposit is hosted in metavolcanossedimentary sequence (anﬁbolite, quartzite, BIF), probably deposited during volcanic episodes in ri systems.

References: ARAÚJO, O.J.B.; MAIA, R.G. 1991. Programa levantamentos geológicos básicos do Brasil. Projeto especial mapa de recursos minerais, de solos e de vegetação para a área do Programa Grande Carajás. Subprojeto Recursos Minerais. Serra dos Carajás, Folha SB.22-Z-A. Brasília: Departamento Nacional da Produção Mineral/DNPM – Companhia de Pesquisa de Recursos Minerais/CPRM, 152 p. CORDANI U.G.; TASSINARI, C.C.G .; KAWASHITA, K. 1984. A Serra dos Carajás como região limítrofe entre províncias tectônicas. Ciências da Terra, 9, 6-11. GRANGER, C. J.; GROVES, D. I.; TALLARICO, F. H. B.; FLETCHER, I. R. 2008. Metallogenesis of the Carajás Mineral province, southern Amazon craton, Brazil: Varying styles of Archean through Paleoproterozoic to Neoproterozoic base and precious-metal mineralization. Ore Geology Reviews. V.33. p. 451489. MONTEIRO, L. V. S., XAVIER, R. P., SOUZA FILHO, C. R. DE, & MORETO, C. P. N. (2014). Metalogênese da Província Carajás. In Metalogênese das províncias tectônicas brasileiras. Editors: Maria da Glória da Silva, Manoel Baretto da Costa Neto, Hardy Jost, Raul Minas Kuyumjian. Belo Horizonte: CPRM. pp.43-92 MORETO, C. P. N.; MONTEIRO, L. V. S.; XAVIER, R. P.; CREASER, R. A.; DUFRANE, A.; TASSINARI, C. C. G.; SATO, K.; KEMP, A. I. S.; AMARAL, W. S. 2015. Neoarchean and Paleoproterozoic Iron Oxide-Copper-Gold Events at the Sossego deposit, Carajás Province, Brazil: Re-Os and U-Pb Geochronological Evidence. Economic Geology and the Bulletin of the Society of Economic Geologists, 110, p. 809-835, 2015.

SILVA, R. C. F. 2009. Evolução e gênese do minério de ferro hidrotermal nos depósitos da serra norte, Província mineral de Carajás. Tese (doutorado) Universidade Federal de Minas Gerais, Instituto de Geociências. TAVARES, F.M. 2015. Evolução Geotectônica do nordeste da Província Carajás. Tese de Doutorado. Instituto de Geociências, Universidade do Rio de Janeiro, Rio de Janeiro. 130p. Teixeira N.A., Freitas-Silva F.H., Corrêa C.R.A., Rosa, W.D., Oliveira J.K.M. de, Rosendo O.S.C., Pinheiro Jr. V. 2009. Evolução geológica e mineralizações primárias da Província Mineral de Carajás. III Simp. Bras. Metalogenia, Gramado, RS. Teixeira, N., Seabra, A., Corrêa, C., Freitas, F., Huhn, S., Siepiersk, L,. Filho, B. A., Souza, C. 2010. A Província Polimetálica de Carajás e seus principais depósitos (Fe, Mn, Au, Cu, Ni, Pt) - Apresentação no Simexmin - ADIMB - Ouro Preto, MG. TEIXEIRA, N. A.; MATOS, F. M. V.; GANADE, C. E.; KLEIN, E. L.; DREHER, A.M.; TAVARES, F. M.; CAMPOS, L. D.; PORTO, F. Carajás and Tapajós Mineral Provinces: Cratonic and Pericratonic Lithosphere Keel Metallogeny. Repositório Institucional de Geociências, CPRM, 2015. TRENDALL, A.F.; BASEI, M.A.S.; DE LAETER, J.R.; NELSON, D.R. 1998. SHRIMP zircon U-Pb constraints on the age of the Carajás formation, Grão Pará Group, Amazon Craton. Journal of South American Earth Sciences, 11 (3): 265-277.

NOTE: The informa on provided here and which may not be part of the SGB-CPRM project is the sole responsibility of the reviewers

Area 1 - Azul mine Thick.

Stratigraphic proﬁles

Area 2 - Serra do Sereno

Description

Fragments of lateritic manganese crust (colluvium) and manganese pisolites

Manganesiferous lateritic crust

Mn 90 m

Mn Mn

Thick.

Thick layers of red-laminated pelite (red bed) interlayered with ﬁne to mediumgrained sandstone and laminated manganesiferous pelite. Sandstones are structured with low angle cross-lamination and wave-ripple cross lamination. Synsedimentary faults occur restricted on some layers in the sequence. Manganese occur precipitated in faults/fractures by tectonic/hydrothermal processes. They form the main ore bodies (high ore content)

Stratigraphic proﬁles

10 m

Manganesiferous crust forms on archean banded manganesiferous iron formation

Metric layer of ﬂuvial coarse-grained sandstone and conglomerate overlied discontinuously marine red and black pelites

40 m

Marine sequence of reddish pelites with lowangle and wave-ripple cross lamination. Convolute laminations recurrently occur along sedimentary package. Gold occur remobilized and precipitated in veins and disseminated in reddish pelites (Serra Pelada). These sedimentary rocks probably have oﬀshore nearby to shoreface marine zone origin

redoxcline Layer of laminated organic-rich black shales

15 m

Turbiditic sequence. Intercalation of centimetric layers of ﬁne to medium-grained sandstones with laminated organic richblack shales. Diagenetic pyrites disseminated in thin layers of sandstone

30 m

Metric layer of laminated manganesiferous pelite. Manganese occurs remobilized and precipitated in faults and fractures. On top of this package manganesiferous pelite occur interlayered with ﬁne to medium-grained sandstones

redoxcline Thick layers of organic-rich black shales. Pyrite disseminated and remobilized in veins

15 m

Mn Mn

Intercalation of centimetric layers of ﬁne to medium-grained sandstone with organic-rich black shales, organized in granodecrescent cycles (normal gradation) typical of turbidite sequence. Diagenetic pyrite occurs disseminated in thin sandstone layers and remobilized in veins. Convolute lamination, cross lamination and climbing ripples structured this turbiditic deposit. Erosion marks often occur at the base of the sandstone layers

45 m

Mn 120 m

Area 3 - Serra da Buritirama Thick.

Stratigraphic proﬁles

Thick.

Stratigraphic proﬁles

Fragments of lateritic manganese crust (colluvium) and manganese pisolites

10m

Lateritic manganesiferous crust

Massive medium to coarse-grained sandstone

Foliated garnet-muscovite-biotite schist

Mn 15m

Mn Foliated medium to coarse-grained quartzite

6m 20 m

Banded manganesiferous iron formation. Manganese occur remobilized and precipitated in faults and fractures

Layer rich in secondary manganese

Fragments of lateritic manganese crust (colluvium) and manganese pisolites Lateritic manganesiferous crust Foliated medium to coarse-grained quartzite

Banded manganesiferous iron formation

Metasedimentary sequence composed of carbonate rocks and banded manganesiferous iron formation. Carbonate occur remobilized in veins. Manganese occurs locally parallel and cutting bedding as a result of secondary remobilization processes. This sequence is structured with tight fold and the manganese crust forms above this sequence.

Area 4 - Antônio Vicente

Description

10m

15 m

Description Fragments of lateritic manganese crust (colluvium) and manganese pisolites

Banded iron formation with restricted levels of manganese (banded manganesiferous iron formation). Manganese also occurs precipitated in planes of fracture and faults, forming highly mineralized levels. The greenish color is a result of alteration of banded iron formation Vulcanic sequence of basaltic and rhyolitic composition

Manganesiferous schist

20 m

Banded manganesiferous iron formation. Manganese occur remobilized and precipitated in faults and fractures

Basaltic volcanic sequence interlayered with banded iron 130m

formation of silicate facies. Synsedimentary faults, accretionary lapilli and convolute

12 m

15 m

laminations occurs locally

Foliated medium to coarse-grained quartzite

Paragnaisse rich in muscovite and biotite. Bands rich in quartz and feldspar alternate with bands rich in maﬁc minerals. Fusion and remobilization occurs locally. It generates migmatites rich in feldspar and quartz along with refractory minerals in the border

Figure 18 - Stra graphic column of the manganese deposits of Carajás region.

Quadrilátero Ferrífero Project Araújo, J.C.S.; Brito, D.C.; Cavalcan , J.A.D.; Couto, M.A.; Feboli, W.L.; Ferreira, R.C.R.; Freitas, F.M.; Marinho, M.de S.; Queiroz, S.F.; di Salvio, L.P.P.; Santos, L.D.; Silva, R. N.;

The Quadrilátero Ferrífero (QF) extends over an area of 7,000 km2 in central Minas Gerais State, Brazil (ﬁgure 1). Its name is due to the form of abundant occurrences of iron forma on and iron ore. The Quadrilátero Ferrífero Project is being developed in the framework of the CPRM Program for Assessment of Mineral Poten al of the Brazilian VolcanoSedimentary Sequences (Program III). The aim of this project is to develop geological and metallogene c models for gold and base metals, allowing the expansion of the knowledge on the economic poten al of this important Brazilian mineral province. In 2016 the project presented preliminary mapping products: mineral resources map of the QF and its surroundings area at a 1: 100,000 scale; geological maps of the QF at a 1:100,000 scale. Its products can be downloaded from the online CPRM database Geobank (h p://geobank.cprm.gov.br/). The QF region was covered by airborne geophysical -44°30'

survey including magne c (figure 2), radiometric (figure 3) and helicopter transient electromagne c (HTEM). CPRM has been modeling several areas with magne za on vector inversion technique which provides good solu ons for characterizing the magne c bodies. . These solu ons could be correlated with the structural control of gold mineralized bodies and their host rocks (figures 4 and 5). When possible the results were integrated with the HTEM and airborne radiometric data available in this region. The Precambrian sec on exposed in the QF consists of four major lithostra graphic units: 1) the Archean metamorphic complexes composed of TTG suites and high-K granites; 2) the Archean Rio das Velhas Supergroup including typical greenstone belt sequence covered by low- to-medium grade metasedimentary units; 3) Paleoproterozoic Minas Supergroup and Sabará Group consis ng of low-to-44°0'

-43°30'

Itabira

BELO HORIZONTE Pará de Minas LEGEND Itacolomi Group: Quartzites -20°00'

Paleoproterozoics Greenstone belts Paleoproterozoics Greenstone belts: Banded Iron Forma ons Sabara Group: Greywacke-argilite sequences tuffs and diamic tes Minas Supergroup: Quartzites, phyllites and dolomites Minas Supergroup: Banded Iron Forma on Rio das Velhas Archean Grenstone Belt Ultramafic, mafic, volcanic and metassedimentary sequences Iron Major Deposits Gold Major Deposits Main Shear Zone or Fault Central Area NW Area Santa Barbara Area

Ouro Preto

Carmo da Mata

30 km

Figure 01 - Schema c geological map of the Quadrilátero Ferrrífero Project area, showing the regions that are being mapped: central (blue polygon) and NW (pink polygon). The map presents Rio das Velhas Archean Greenstone Belts that host world class gold deposits and the Minas Supergroup that hosts world class iron deposits. Light blue polygon indicates the area modelled with magne za on vector inversion technique.

-20°30'

Congonhas

Figure 02 - Analy c signal map of QF. The strong magne c anomalies corresponds to the BIF-rich Minas Supergroup.

Zucche , 2007) (figures 7 and 8). Cycles 1, 2 and 3 comprises the Nova Lima Group. Cycle 1 is interpreted to have occurred between 2,800-2,780 Ma based on the ages of the mafic and felsic volcanism, and comprises predominantly maficultramafic koma i c tholeii c volcanic flows with intercala ons of chemical sedimentary rocks. The cycle is related to the ini al extensional stage of the greenstone belt development, with the deposi on of sediments contemporaneous with the volcanic flows that formed the submarine oceanic plains.

medium grade metasedimentary rocks; and 4) the Itacolomi Group composed of metasandstones and conglomerates. The Archean metamorphic complexes include 3.2-2.9 Ga gneisses, migma tes, showing typical TTG suites signatures. These rocks typically display well developed composi onal banding and show various genera ons of tectonic structures. Two genera ons of late intrusive granitoids are found in the region. The older genera on of granitoids has a calc-alkaline aﬃnity and yields U/Pb zircon ages of 2,78 to 2,76 Ga, whereas the younger suite presents high-K signatures and has been dated between 2,75-2,6 Ga. Those bodies occur as domes with diameter exceeding 50 km and display both isotropic fabrics and discrete shear zones, developed especially along the contact with the supracrustal units.

Cycle 2 encompasses clas c-chemical-sedimentary associa on and distal turbidites in the eastern sector of the Quadrilátero Ferrífero. It was deposited in the ini al stages of the subduc on phase. Cycle 2 includes the coastal (sandstone with medium-tolarge scale cross-bedding, sandstone with ripple marks, sandstone with herringbone cross-bedding, sandstone-siltstone) and resedimented associa ons (graywacke-argillite) in the southern sector.

The metavolcano-sedimentary rocks of the Rio das Velhas Supergroup in this region are subdivided into the Nova Lima and Maquiné Groups (ﬁgure 6). The former occurs at the base of the sequence and contains the major Au deposits of the region. Deposi on occurred during four cycles (Baltazar and

Cycle 3 comprises felsic volcanism, sedimentary volcaniclas c and resedimented rocks (monomic c and polymic c breccias, conglomerate-graywacke,

Figure 03 - Colour composite (ternary) image over the Quadrilátero Ferrífero Project area. The maﬁc and ultramaﬁc rocks of the basal unit of the Rio das Velhas Supergroup are poor in radioelement concentra ons, marked by the dark zones. The highest potassium regions are interpreted as hydrothermal zones, commonly associated with gold deposits.

graywacke-sandstone, graywacke-argillite), largely in the northern sector of the area. These associa ons indicate a submarine fan environment transi onal to non-marine successions related to felsic volcanic ediﬁces and the forma on of island arcs. The felsic metavolcanics were U-Pb dated with ages of 2,776 Ma and 2,772 Ma. U–Pb zircon da ng of volcaniclas c rocks at 2,792 Ma, 2,773 Ma, and 2,751 Ma suggest a dura on of about 40 Ma for the erup ve felsic magma sm within the greenstone belt, which was coeval with the oldest genera on of calk-alkaline granitoids of the QF. Cycle 4 is made up of clas c sedimentary rocks belonging to the non-marine lithofacies associa ons (conglomerate-sandstone, coarse-grained sandstone, ﬁne-tomedium grained sandstone) of the Maquiné Group. They are interpreted as braided plain and alluvial fan deposits in a retroarc foreland basin with the supply of debris from the previous cycles. Gold deposits in the Rio das Velhas greenstone belt

are structurally controlled and occur associated with hydrothermal altera ons along Archean thrust shear zones. Currently they were classified by Lobato et al. (2001) as orogenic gold deposits formed at around 2,72-2,67 Ga, during the final stages of the Archaean orogenesis (figure 8). The main mineraliza on styles are: (1) structurally controlled sulfide replacement zones in banded iron forma on; (2) disseminated sulfide in hydrothermal rocks along shear zones, (3) quartz-carbonate-sulfide veins in mafic, felsic volcanic rocks and clas c sedimentary rocks. The gold-bearing disseminated to massive sulfide stratabound ores of the Rio das Velhas Supergroup likely formed as epigene c replacements in oxide, sulfide, or carbonate facies BIF (figures 9 and 10). Those chemical sediments make up most of the country rock of the gold deposits of the QF. The fluids that form these deposits were enriched in CO2 and 18O and reached temperatures ranging between 325400°C at low-to-moderate salini e.

Top View SE Bottom View

A 7790000

Córrego do Sítio II

Pilar 5k

Córrego do Sítio I 7785000

A B

655000

660000

Magnetic Susceptibility Isosurface (>0.02 SI)

NE View 0.04560 0.01120 0.00724 0.00464 0.00390 0.00316 0.00242 0.00168

~1000m

0.00094 0.00020

Magnetic Susceptibility (SI Units)

Figure 04 A - The Magne za on Vector Inversion solu on for Santa Bárbara region shows a strong magne c body (k>0.02 SI) associated with BIFs well correlated to the linear magne c anomaly along NE-SW direc on. The magne c body shows a strong remanent magne za on (see the magne za on vectors direc ons) and presents a synformal structure (NE view), with depth extension about 1000 m and length 5 km along NE direc on, approximately. Possibly, this magne c body is correlated to the Conceição syncline, associated with the Córrego do Sí o Lineament. Further studies with MVI technique and integra on with the HTEM modeling could help to be er understand this structure and its associa on with gold deposits along this lineament.

B R i o d a s Ve l h a s S u p e r g r o u p MAQUINÉ GROUP (Clastic metassedimentary association - coastal and fluvial)

Casa Forte Fm. - Chica Dona Un. Casa Forte Fm. - Córrego do Engenho Un. NOVA LIMA GROUP

Palmital Fm. - Rio de Pedras Un. Mindá Un. (marine clastic metassediments) Córrego do Sítio Un. (marine clastic metassediments) Santa Quitéria Un. (BIFs) Santa Quitéria Un. (chemical pelitic metassediments) Ouro Fino Un. (plutonic metavulcanic rocks) Quebra Osso Un. (metaultramafic and mafic rocks) Gold Mine

Barão de Cocais

Santa Bárbara CÓRREGO DO SÍTIO II PILAR

CÓRREGO DO SÍTIO I

8km

Figure 04 B - Geological map of Santa Bárbara region. The main rock units comprise a metamorphosed succession of schistose sediments of the Nova Lima Group, Rio das Velhas greenstone belt, which host lode-gold mineraliza on associated with BIF's (Pilar and Córrego do Sí o II deposits) and quartz-carbonate-sulﬁdesulfosalt veins (Córrego do Sí o I deposit).

São Sebastião Deposit

7850000

ESE View Pequi Anomaly

Conceição do Pará Anomaly

7830000

7850000

7840000

7830000

Magnetic Susceptibilty Isosurface (>0.15 SI)

0.01361 0.00522 0.00270 0.00253

N view

0.00235 0.00218 0.00201 0.00183

7810000

0.00166 0.00148 0.00131 0.00096 0.00079 0.00061 0.00044

510000

530000

São Sebastião Deposit

0.00026 0.00009

550000

520000

504000

520000

536000

7840000

Magnetic Susceptibility (SI Units)

530000

10km

7824000

LEGEND

Rio Pará

Shear zones and lineaments Agalmatolite deposits Gold deposits and occurrences Quartz digging mines Recent sedimentary covers Proterozoic sediments of Bambuí Group

São Sebas ão Deposit

Rio São João

agl

Metahidrothermalites with subordinate agalmatolites (agl) e magnetitites (mt). SIN TO LATE TECTONIC GRANITOIDS Tonalite to granodiorite granitoids (~2,7 Ga) mt

7808000

RIO DAS VELHAS SUPERGROUP MAQUINÉ GROUP Quartzites with subordinate intercalations of oligomitic metaconglomerates NOVA LIMA GROUP Metagreywackes, metapelites with ff metaconglometares, metarenites, metatuffs, banded iron formations (ff) intercalations. Fine-grained clastic metasediments interlayered with meta-lapilli-tuffs and metagglomerates. mu Metamafic volcanic rocks with minor ms ff intercalations of metaultramafic (mu), metavolcanoclastics, cherts (ms) and banded iron formations (ff). CRYSTALLINE BASEMENT Gneisses and migmatites of Divinópolis Complex

Figure 5A - MVI results for the Pará de Minas by many perspec ves. Observe the strong magne c body associated with the NW lineament (Pequi anomaly - shear zone). The NW por on of this magne c body is probably correlated with magne c BIFs in this region, which seems prolate-oblate shape plunging 40-45° to NW. This magne c body has a great prospec vity importance, because its structural and posi on model could contribute to the metallogenic and structural understanding of the area. Figure 5B - Schema c geological map of northwest area presen ng Rio das Velhas Supergroup lithostrigraphic units and the main gold, agalmatolite e quartz deposits. São Sebas ão deposit is highlighted.

Stra graphic Columns of the Rio das Velhas Greenstone Belts

v v v v v v

v v v

Lithological Association Sandstone-conglomerate (matrix and clast-supported)

Continental alluvial fan and fluvial deposits

Depositional Systems

Sandstone-siltstone

Proximal volcanogenic turbidites

Greywacke-argilite,

Volcanogenic distal turbidites of Na-rich felsic source

500 0 Meters

MAQUINÉ GROUP

Casa Forte Fm. Rio das Pedras

CYCLE III

Mestre Caetano

Volcanoclastic rocks of emergent island arcs, Volcanogenic conglomerate-greywacke, breccias braided sandstones, alluvial fan breccias (polymitic and monomitic), greywacke-sandstones fluvial and conglomerates

Ribeirão Vermelho

Sandstone

Coastal sediments (aeolian, tidal plain)

Andaimes (São Bartolomeu Domain)

Graywacke-argilite (calc-silicatic rocks and banded iron formations)

Resedimented turbidites (distal or proximal) of felsic and mixed sources

Pelites and banded iron formations

Pelagic and chemical marine sedimentary rocks

3 1000

Stratigraphic Unit CYCLE IV

NOVA LIMA GROUP

CYCLE II

Catarina Mendes, Pau d’Óleo, Córrego Paina, Fazenda Velha (São Bartolomeu Domain) Córrego do Sítio, Mindá (Santa Bárbara Domain)

CYCLE I

Morro Vermelho Ouro Fino Quebra-Osso, Córrego dos Boiadeiros Complex

RIO DAS VELHAS SUPERGROUP

Santa Quitéria (Santa Bárbara Domain)

Basalts and banded iron formations Subaqueous mafic-ultramafic-volcanics Komatiites, basalts (cherts and banded iron formations) partially associated with chemical sediments

Gold mines: (1) Morro Velho, Cuiabá, Lamego; (2) Córrego do Sítio; (3) São Bento; (4) Raposos

Figure 06 - Stra graphic column of the Rio das Velhas Greenstone Belt. Adapted from Baltazar and Zucche

2007. fluvial sandstone

Proximal Turbidite turbidite

Agglomerate

Distal Turbidite Volcanoclastic BIF Basal c Flows - Pillow Lavas

Basal c Flows - Pillow Lavas Banded Iron Forma on, Cherts Diferen ated Spinifex - Flows Sheet-Flows Facies Olivine Orthocumulate Olivine Adcumulate Dunite Lenses - Channel Facies

A ic

Pillow Basalts

Alluvial Fans Braided Rivers BIF Exhalative Fe-Mn-Si Sediments

o VTurbidites

Vulcanoclastic Distal Turbidites

Basalts

Potassion-Rich Granites

Cherts- B I F

Poding of Magmas Komatiite In Mid-Ocean Ridge Archean Ocean Floor

TTG

Partial melting of hydrated mantle Asthenospheric Metasomatized Aqueous fluid Mantle

Deep Water Sediments Turbidites

Melting of oceanic crust Dehydration of Oceanic crust

Decompressional Melting Melt of Sediments

Breakdown of Serpentine and amphybole

Figure 07 - Schema c model of greenstone belt evolu on.

Melting of Sodium -Rich Granites Partial Melting of Hydrated Mantle Magma Crack Propragation

RdV I

RdV II

Mam

Machado et al. (1992, 1996) Noce et al. (2005)

GOLD MINERALIZATION Pb/Pb (Apy-Py) São Bento Mine 2.65 Ga De Witt et al., (1996)

Frequency

ID-TIMS (N=21)

2761 Ma 12

LA-ICP-MS (N=23) Machado et al. (1996)

U/Pb SHRIMP Morro Velho and Cuiabá Mines 2672±14 Ma Lobato et al., (2007) Lamego Mine 2730±42 Ma Martins et al. (2016)

SHRIMP (N=45) Noce et al. (2005) Hartmann et al. (2006)

2850 Ma 8

All zircons are < 10% disc. Bin width 40 Ma

2943 Ma 3174 Ma

Density probability plot

0 2800

3000

3200

3400

3600

3800

Age (Ma) Figure 08 - Frequency histogram showing the age distribu on of detrital zircon grains in the rocks of the Rio das Velhas Supergroup. Ver cal bands mark the age of the main magma c events in Quadrilátero Ferrífero region. Yellow star marks the ages of the main gold mineraliza ons. The data compila on is available in Farina et al. 2015.and references therein.

Courtesy Rodrigo Martins Figure 09 - Main photo: Banded and massive suphide. Upper photo: Drillhole presen ng free gold in quartz veins. Cuiabá mine.

Figure 10 - Sulﬁde-rich BIF, host rock of the Lamego orogenic gold mineraliza on from the Rio das Velhas Greenstone Belt. Lamego undergrounded mine is operated by AngloGold Ashan in Quadrilátero Ferrífero, Minas Gerais, Brazil. Photo credits: Joanna Araújo

NOTE: The informa on provided here and which may not be part of the SGB-CPRM project is the sole responsibility of the reviewers

Baltazar, O.F; Zucchetti, M. 2007. Lithofacies associations and structural evolution of the Archean Rio das Velhas greenstone belt, Quadrilátero Ferrífero, Brazil: A review of the setting of gold deposits. Ore Geology Reviews, 32(3), 471-499. Farina, F., et al., The ArcheanePaleoproterozoic evolution of the Quadril_atero Ferrífero (Brasil): Current models and open questions, Journal of South A m e r i c a n Ea r t h S c i e n c e s ( 2 0 1 5 ) , h t t p : / / d x . d o i . o r g / 1 0 . 1 0 1 6 / j.jsames.2015.10.015. Lobato, L.M; Ribeiro-Rodrigues, L.C; Vieira, F.W.R. 2001. Brazil´s premier gold deposits. Part II: geology and genesis of gold deposits in the Archean Rio das Velhas greenstone belt, Quadrilátero Ferrífero. Mineralium Deposita, 36: 249277.

Tapajós Project Fhábio Pinheiro, Cesar Chaves, João M. Castro, Manoel C. Neto, Marcelo Vasquez, Vanessa Lobato

The Tapajós Project is being developed as part of the CPRM Geological-Geophysical Integra on Program for Predic ve Mapping of Prospec vity of Brazilian Shields. This project aims to determine the regional and local controls of the known gold and base metals mineraliza on and to indicate favorable areas for mineral explora on, in order to provide a background data that could upgrade the ongoing explora on programs by mining companies. The Authors: Raphael T. Correa, Bruce F. Chiba, Marcelo Vasquez, Cesar Chaves, Fhábio Pinheiro.

-58°

project encompasses parts of two geochronological provinces located on the southwestern edge of the Amazon Craton (northwest Brazil): Tapajós - Parima (2.03-1.88 Ga) and Central Amazônia (1.88 Ga; Santos, 2003). According to Cordani et al. (1984) the Archean Amazon Craton is surrounded by progressively younger orogenic belts that amalgamated to form a coalescence of accreted terranes (Figure 1).

-57°

-56° Magnetic Lineaments Falt

To c

Magnetic Blocks

tiz

inh

Au deposits

old

-6°

Tre n

-55°

Simplified Lithostratigraphic Units Fanerozoic sedimentary rocks. Cachoeira Seca/Suite: gabbros e anortosites Buiuçu formation: conglomerates, sandstone Maloquinha Suite: sienogranites, monzogranites, quatz-syenite Moraes Almeida Formation: Ignibrites, trachytes Ingarana Suite gabbros and anortosites Bom Jardim Formation: andesites Paraurai Suite/granite unit Paraurai Suite/granodiorite unit: Monzogranites, granodirites and Salustiano Formation: Rhyolites and dacites Tropas Suite: Tonalites, monzonites and granodiorites Jacareacanga Group: Shists pelites, metamafic, metautramfic and quartzites Creporizão Suite: monzonites, sienogranites, Chapeu do Sol Formation – Ryolites and andesites -8° Vila Riozinho Formation: Ignibrites, rhyolites and andesites Cuiú-Cuiú Complex - Tonalites and monzonites Comandante Arara Formation - Ignibrites and trachytes Castelo dos Sonhos Formation - Sandstone and conglomerate

Geological Section

Major Gold Corridor

-7°

50km

LTCZN

B Maloquinha Suite: sienogranites, monzogranites, quatz-syenite Moraes Almeida Formation: Ignibrites, trachytes

Ingarana Suite gabbros and anortosites Paraurai Suite/granite unit Cuiú-Cuiú Complex - Tonalites and monzonites

Creporizão Suite: monzonites, sienogranites, Vila Riozinho Formation: Ignibrites, rhyolites and andesites

Falt Au quartz veins

Figure 01 - Tapajós geological map. Magnetic gradient variation the main structures of the Tapajós fault system. Euler deconvolution from magnetic and gravity data to enhance main geological contacts and faults. The geological model shows that Tocantizinho trend is a deep crustal discontinuity.

The Tapajós Gold Province (TGP) (Cou nho, 2008) is located on the south-central portion of the Amazonian Craton, in the Pará and Amazon States. It has a total historical produc on of about 780 tons of gold extracted mainly by handcra ed digging of rivers and streams, and subordinately from hundreds of ar sanal small open pit and underground mines. There is currently only one mine in opera on at Tapajós (Palito mine, 668 KOz Au, Serabi Gold) and one major project under development (Tocan nzinho, 1,824 MOz Au in reserves and 2.115 MOz Au in resources, Eldorado Gold). Other signiﬁcant deposits, s ll in explora on stage, are São Jorge (1,584 MOz Au, Gold Mining), Coringa (913 KOz Au, Anﬁeld) and Boa Vista (336

KOz, Gold Mining). Considering only the five main gold deposits in the region, a total resource of 7.5 MOz has been reported, mostly by Canadian and Australian mining companies. The basement of the project area is characterized by plutonic rocks, gneisses, migma tes (2.04-2.02 Ga Cuiú-Cuiú Complex) and a restricted volcanosedimentary unit (Jacareacanga Group). These rocks show calc-alkaline affini es of medium-K and juvenile isotopic signatures. The Cuiú-Cuiú granitoids are representa ve of magma c arcs or ac ve con nental margins (Almeida et al., 2007; Vasquez et al., 2008). The figure 02 shows underformed plutonic-volcanic sequences that cover par ally basement. Some of theses sequences are 1893-1869 Ma

1898-1881 Ma

2002-1959 Ma

1893-1869 Ma

3 2033-2005 Ma

2020-2012 Ma

1892-1879 Ma

1882-1862 Ma

1997-1956 Ma

1907-1893 Ma

1 ~2050 Ga 1 2 3 4 5 6 7

2033-2005 Ga

Jacareacanga Group (2,050 Ga) - pelític shist, quartzites, metamaﬁc and metaultramaﬁc Cuíu-Cuíu Complex - Tonalites, Monzogranites and migmatites Comandante Arara Formation - Ignibrites, rhyolites, andesites e vulcanoclástic Crepori / Vila Riozinho Event - Ignibrites traquites, andesites, Ryolites, vulcanoclastic and sediments. Tropas Event- Tonalitos e Monzogranitos Dacitos, latitos, andesitos e basaltos Maloquinha / Iriri Event - Sieno granitos, monzogranitos e granitos Ignibritos, riolito, dacitos e traquitos Parauari / Bom Jardim Event - Monzogranites e diorites, dacites and basalts

Figure 02 - Shows the basement made of Cuiú-Cuiú complex and Jacareacanga volcanosedimentary sequence. Addi onally it is possible to see four plutonic-volcanic events some of them accompanied by sedimentary deposi on

considerated part of Uatumã SLIP (Fraga et al., 2015 unpublished). The plutonic and volcanic rocks of the Silicic Large Igneous Province (SLIP) show geochemical signatures of an A-type or high-calcium alkaline suite (Vasques and Dreher, 2011). They comprise several volcanic lithostra graphic units (Iriri, Bom Jardim,) and granitoids (Maloquinha, Velho Guilherme, Rio Dourado, Parauari, Tropas), with ages between 1.90 and 1.86 Ga (Fraga et al., 2015). The Sm-Nd modelled ages are Rhyacian and occasionally Neoarchean, with εNd(t) varying from -6.7 to -0.7 in the Tapajós Domain, and Meso- to Neoarchean in the Iriri-Xingu Domain, with εNd(t) between -5.35

and -12.1 (Fraga et al., 2015 unpublished). The volcanic rocks are dominantly rhyoli c to daci c ignimbrites, also known as ash-flow tuffs. Felsic to andesi c lavas, subvolcanic rocks and ash-fall tuffs occur subordinately as compared to the extensive ignimbrite deposits. Vila Riozinho volcanic unit is older than Iriri but it shows the same lithological components and volcanic style. That unit is made of strongly welded daci c ignimbrites including plagioclase, K-feldspar and subordinate quartz crystals, together with fla ed pumice fragments set in a microcrystalline, felsic, flow-foliated matrix (Figure 3). Other rock-types in this unit are trachy c and andesi c flows (Figures 3, 4 and 5).

Pm Kf

Foto credit Ana Dreher

Figure 03 –Daci c ignimbrite of the Vila Riozinho Forma on containing plagioclase (Pl), K-feldspar (Kf) crystals and stretched pumice par cles (Pm) set in a microcrystalline felsic ﬂow-foliated matrix. Sample MV-265. Plane-polarized light. Scale 1mm.

Foto credit Ana Dreher

Figure 04 –Welded daci c to andesi c ignimbrite a ributed to the Iriri unit showing zoned plagioclase crystals (Pl) , altered maﬁc phases and pumice fragments (Pm) in a very ﬁne grained groundmass. Sample CE-24. Plane-polarized light. Scale 1mm.

Three main types of gold mineraliza on are known at TGP (Figures 3 and 4): (1) Compressional shear veins associated with the Jacareacanga and CuiúCuiú units, with restricted sericite, carbonate and chlorite altera ons (Espírito Santo, Bom Jesus, Pepeu, Chico Torres, Jerimum de Cima garimpos), and considered as orogenic gold or intrusion related type deposits (Cou nho, 2008; Vilas et al., 2013; Assunção and Klein, 2014); (2) Extensional epithermal high-grade quartz veins with comb texture and adularia, indis nctly hosted by the plutonic-volcanic sequences of Creporizão-Riozinho (2,000-1,968 Ma), Parauarí-Moraes de Almeida (1,898-1,880 Ma) and Maloquinha-Iriri (1,890-1,864 Ma), as at Carneirinho, Goiano, Pison and Abacaxis garimpos (Dreher et al., 1998), and; (3) High sulﬁda on low-grade gold deposits (e.g. V3) (Jacobi, 1999; Juliani et al., 2014) (Figures 6, 7 and 8).

Palito Mine V3

Argilic Altera on

Sub-volcanic Intrusive Related to Maloquinha Granite (Synchronous to Shearing)

Chlorite Filled Sheets or Faults (Chl-Carb-Fluorite) Quartz Sulfide Veins with Strong Chlorite Wall Rock Alteration Sinous Veins Hosted by Maloquinha Granite

Magma

Leandro, et al, 2015 unpublished Legend Maloquinha and Parauari Granites Creporizão, Cuiú-Cuiú Granites

Figure 06 - Schema c model of Tapajós gold mineraliza ons. Note that the mineralized veins and subvulcanic bodies are controlled by bri e shear zones. Palito Mine in detail.

Abacaxis

Goiano

Bom Jesus Phillic Alteration São Jorge

Carneirinho

Ingarana

Davi 1,891 Ma

Phylic

Tapajós Gold Mineralizations

Davi

Figure 05 –Densely welded rhyoli c ignimbrite of the Moraes de Almeida sequence, displaying K-feldspar (Kf) and quartz (Qz) crystals and a folia on deﬁned by ﬂa ened aligned pumice lapilli (Pm). Sample AT-02 A. Plane-polarized light. Scale 1mm.

Pepeu

Parauari

Moraes Gomes Creporizão Espirito Santo Maloquinha Jacareacanga - Cuiú-Cuiú

1.997 Ma Guarim

2.0 - 1.95 Ga

Maloquinha Modiﬁed from Santos, 2008

Figure 07 - Scheme showing several small gold deposits in the Tapajós region. Note the predominant occurrence of quartz veins in the shear bri le zones enveloped by phyllic altera on

Vuggy Sílica

Winding pyrite-quartz veins with hematite in alteration helo in Maloquinha granite.

Epitherma breccia with quatz sericite alteration

Mineralized quartz-chlorite-pyrite-chalcopyrite veins in ductile shear zone. Note chlorite alteration halo, restricted to the veins´s edge in Maloquinha granite. Palito underground mine.

Quartz-fluorite vein with druses and chlorite alteration halo in Maloquinha granite

Mineralized quartz-chlorite-pyrite-carbonete veins in ductile shear zone. Note chlorite alteration halo, restricted to the veins´s edge in Maloquinha granite. São Chico underground mine.

Figure 08 - Geological features of Tapajós gold mineraliza on

The geotectonic evolu on of the Tapajós Gold Province and its surrounding terranes is subjected to strong scien ﬁc debate. Teixeira et al. (2014) suggested that the TGP gold deposits are related to intra-con nental magma sm at the edge of a ri ed cratonic keel that channeled asthenosphere derived melts to the ri ed margins at 2.0-1.88 Ga. (Figure 9). The dominance of felsic magma and its large volume can be explained by the inﬂuence of a mega plume that pounded at the base of the crust, yielding

extensive underpla ng and bimodal volcanism (Santosh, 2015) (Figure 10 and 11). The gold mineraliza on at TGP has about the same age as Maloquinha, Parauarí plutonic-volcanic sequences which represent a huge con nental magma c event that covers a large por on of the Amazon craton area (Fraga et al., 2015) (Figures 12, 13 and 14).

Tapajós Gold Mineralization - Geotectonic Setting

Parauarí

Maloquinha

Araguaia Ofiolite Cuiú-Cuiú

Carajás

Lithosphere Keel

SCLM Keel Edge Figure 09 - Tapajós gold province is hosted by a volcanic-subvolcanic-plutonic magam c system driven by maﬁc underpla ng-plume event. Probably during the Paleoproterozoic, a larger plume was deﬂected and channelled to a ri ed-edge keel (100 Km-thick). The TGP is an inherited characteris c of the disturbed SCLM during ri ing events.They are not related to the forma on of a convergent plate margin.

Uatumã LIP - 1.90 - 1.86 Ga Intracon netal Ri

Cuiú-Cuiú Mobile Belt

Cuiú-Cuiú

Bacajá Mobile Belt

Carajás

Uatumã: Maloquinha-Iriri-Parauari

Bacajá

SCLM Stagnant Slabes

410 km 1893-1864 Ma

660 km ? Slabe avalanche

Figure 11 - Geotectonic se ng of the Uatumã FLIP. This Super Plume could be triggered by avalanches of Transamonian slabs when they arrived in the Transi on zone in similar model proposed by Pirajno and Santosh (2014).

Lower Mantle Super pluma

Figure 10 - Fraga et al., (2015), proposed that the subduc on of oceanic plates peripheral to the Amazon craton may have favoured the forma on of Uatumã SLIP. Pirajno and Santosh (2014), explain the worldwide development of the enormous amount of felsic magmas by plumes triggered by avalanches of the pieces of ocean ﬂoor desestabilized gravita onally in the Tranzi on zone

Core-Mantle Boundery

Epitermal Mineraliza on 1.869 - 1.870 Ga (Juliani et al. 2014)

Tapajós post-calderas Volcanoes Ash ﬂow, andesite and tuﬀs

Gold Mineraliza on Porphyry

Phylic Altera on

1892-1879 Ma

Parauari and Maloquinha magma c chambers

1. Epitermal deposits in breccias and veins 2. Qz Veins close to the magma c chamber 3. Mineraliza on in phylic altera on zones

1.882-1.862 Ga

Intracon nental magma sm

Figure 12 - Volcanic se ng of Tapajos area formed by ignimbrites , rhyoli c and dacite in subaerial calderas (Par ally modiﬁed from Juliani et al., 2014) The gold mineraliza on is related to subvulcanic phorphyry, plugs and quartz veins wrapped by phylic altera on zone.

10km

Figure 13 - Maloquinha and Parauari volcanic se ng formed by coalescence of calderas and ﬁlled up by ignibrites, rhyolites and dacites. Taken from Juliani and Fernandes (2010) 52°W

64°W

Atl an tic

VENEZUELA GUIANA

10°N

e a

GUIANA FRANCESA

Phanerozoic cover LATE-OROSIRIAN - CALYMMIAN - MESOPROTEROZOIC Undivided units

SURINAME

Sedimentary rocks (>1,78 Ga)

BRASIL

nas

mazo

Rio A

jós

ro OROSIRIAN Calc-alkaline A-type granites with high-K and gneisses, charnockites e granulites (1,95 -1,93 Ga) Supracrustal Rocks in Greenschist facies (1,95 Ga) Orocaima Magmatism Granitoids and A-type calc-alkanine vulcanic rocks with high-K (CA) and S-type calc-alkaline granitoids (CS) with high-K (1,98-1,95 Ga). (=) Granitoids ~1,99 Ga in the Província Alta floresta (PA) with archean remains

Tap a

Uatumã Magmatism Felsic vulcanic rocks (to interm.) and undivided granitoids. Rio Calc-alkaline affinity A-type with high-K (1,90-1,86 Ga)

Rio

Supracrustal rocks in anfibolite to granulite facies and S-type granites (2,00 Ga?) Supracrustal rocks in greenschist to anfibolite facies

gu Xin

Iriri

Granitoids and greenstone belt sequences (2,21-2,07 Ga) and granite-gneiss terrains ARCHEAN WITH PALEOPROTEROZOIC REWORKED CI Felsic granulites and gneiss with archaen heritage reworked in the Orosirian (Complexo Imataca - CI) Archean units in Bacajá (BJ) and Santana do Araguaia domains and Amapá Block (AP), reworked in Rhyacian ARCHEAN Carajás Domain (3,0-2,5 Ga) Rio Maria Domain (>3,0-2,8 Ga)

Rio

Granitoids and calc-alkaline gneisses (T-Trairão; A- Anauá; C-Cuiu-Cuiui) (2,04- 2,02 Ga), granite-gneiss terrains RHYACIAN Granulites and charnockites (2,06Ga) Intracatonic to platform sedimentary sequences (siderian/ rhyacian?) C

Approximate limit between Tapajós (DT) and Iriri-Xingu (DI) domains from the isotopic signature Cinturão Cauarane-Curuni shear zone

10°S

200 km

Figure 14 - Amazonian Geological Map. The con nental extension of the Uatumã (FLIP) is highlighted in orange (Fraga et al., 2015)

NOTE: The informa on provided here and which may not be part of the SGB-CPRM project is the sole responsibility of the reviewers

References ALMEIDA M.E.; MACAMBIRA M.J.B.; ELMA, C.O. 2007. Geochemistry and zircon geochronology of the I-type high-K calc-alkaline and S-type granitoid rocks from southeastern Roraima, Brazil: Orosirian collisional magmatism evidence (1.97–1.96 Ga) in central portion of Guyana Shield. Precambrian Research. 155, 69–97. CAMPOS, L., TEIXEIRA, N.A. and GANADE, C. Relatório Interno SGB-CPRM Atividades de Campo, Tapajós, Alta Floresta, 2015, unpublished. COUTINHO, A. M.; 2008. Província Mineral de Tapajós e Mapa Previsional para Ouro em SIG. CPRM, Rio de Janeiro, 4209. DREHER, A. M.; VLACH, S. R.; & MARTINI, S. L. (1998). Adularia associated with epithermal gold veins in the Tapajós Mineral Province, Pará state, northern Brazil. Brazilian Journal of Geology, 28(3), 397-404. JACOBI, M. (1999). The discovery of epithermal Au-Cu-Mo proterozoic deposits in the Tapajós Province, Brazil. Brazilian Journal of Geology, 29(2), 277-279. JULIANI, C. AND FERNANDES, C.M.D. Well preserved Late Paleoproterozoic volcanic centers in the são Felix do Xingu region, Amazonian Craton, Brazil. Journal of Volcanology and Geothermal Research 191 (2010) 167-179. KLEIN, E. L.; ALMEIDA, M. E.; ROSA-COSTA, L. T.; 2012. The 1.89-1.87 Ga Uatumã Silicic Large Igneous Province, nothern South America. Large Igneous Province Comisssion, November 2012 LIP of the Month. LÊDA, M. F.; VAZQUES M. L.; ALMEIDA, M. E. & REIS, N. 2015. A influência da

orogenia eo-orosiriana na formação da slip Uatumã, parte central do craton amazônico CPRM – Serviço Geológioco do Brasil (inédito). JACOBI, M. (1999). The discovery of epithermal Au-Cu-Mo proterozoic deposits in the Tapajós Province, Brazil. Brazilian Journal of Geology, 29(2), 277-279. JULIANI, C. AND FERNANDES, C.M.D. Well preserved Late Paleoproterozoic volcanic centers in the são Felix do Xingu region, Amazonian Craton, Brazil. Journal of Volcanology and Geothermal Research 191 (2010) 167-179. SANTOS J. O. S. 2003. Geotectônica dos Escudos das Guianas e Brasil Central. In: Bizzi, L.A.; Schobbenhaus, C.; Vidotti, R.M.; Gonçalves, J.H. Geologia, tectônica e Recursos Minerais do Brasil. Brasília: CPRM. p. 198. TEIXEIRA, N. A.; CAMPOS, L. D.; CARVALHO, M. T. N.; CUNHA, L.M. Porphyry or not porphyry; That´s not the only question. 2015. Repositório Institucional de Geociências, CPRM, 2015. VASQUEZ M.L. & DREHER A.M. 2011. Uma avaliação da estratigrafia dos eventos magmáticos de 1900-1860 Ma do Cráton Amazônico. IN: 12° SIMPÓSIO DE GEOLOGIA DA AMAZÔNIA. BOA VISTA, RESUMOS EXPANDIDOS. VASQUEZ M.L.; ROSA-COSTA L.T.; SILVA C.M.G.; KLEIN E.L. 2008. Compartimentação tectônicA. IN: VASQUEZ M.L., ROSA-COSTA L.T. (EDS.) Geologia e Recursos Minerais do Estado do Pará: texto explicativo dos mapas Geológico e Tectônico e de Recursos Minerais do Estado do Pará. Escala 1:1.000.000, Belém, CPRM, p. 39-112.

Juruena-Teles Pires Project Gilmar J. Rizzo o, Cléber L. Alves, Francisco S. R., Tiago Bandeira Duarte, Leonardo L. Lopes, Gabriel de F. Gonçalves

The Juruena-Teles Pires Project is part of the CPRM Program for Geological-Geophysical Integration and Predictive Prospectivity Mapping of the Brazilian Shields. The Project is focused on the Alta Floresta Gold Province (AFGP) which historically has produced around 300 tons of gold (Figure 1). This province is located in the north of Mato Grosso State, comprising a 600-km long section of alluvial and primary gold occurrences, extending from the

Moriru

-59º

Peixoto de Azevedo and Matupá towns (eastern part of the region) to the Juruena River (western part). This region also includes the Zn-Pb-(Cu) deposit in Aripuanã. Despite of the mineral importance of the area, basic geological and geochronological knowledge is still poorly developed. Several different deposit types have been inaccurately described at the (AFGP) (e.g. porphyry, epithermal, orogenic, intrusion, related).

-57º

-55º

Juruena Novo Astro

Álvaro Tavares

Papagaio Ico

Zé Vermelho

APIACÁS PARANAÍTA

Trairão

NOVA BANDEIRANTES ALTA FLORESTA

-10º

Rato

Guarantã Ridge

Luizão

S. Guarantã

Aripuanã Zn-Pb-(Cu)

X1 Peteca Paraíba

MATUPÁ P. AZEVEDO

Pé Quente Fabinho/Gil Francisco

Tapajós

60km

COLÍDER

-59º

-58º

< 1.6 Ga Granites and gabbros 1.75-1.70 Ga Volcano-plutonic associa on 1.81-1.75 Ga 1.82-1.77 Ga

Sedimentary rocks K-feldspar-rich granitoids Acidic volcanic rocks Isotropic granitoids Deformed granitoids

-57º

1.82-1.77 Ga 1.81-1.79 Ga ~ 1.87 Ga > 1.95 Ga

-56º

-55º

Tectonic and Structures

Metabasic rocks High-grade metamorphic rocks

Structures interpreted from surface and subsurface data Normal fault Mineral deposits

Monzogranite and monzonite Gabbro and diorite Orthogneissic and grani c basement

58°0'0'’

Ac ve ar sanal mines Deac vated ar sanal mines Towns

56°0'0'’

Geophysical Lineament Gold Deposits Occurrences Gold 0

City

60km

Paranaíta

10°0'0'’

Nova Bandeirantes Alta Floresta Matupá

Colíder

Figure 01 - (A) Simpliﬁed geological map from the project area. (B) Geophysical lineament interpretation from the project area and the principal gold occurrences and deposits

Part of the adversity of classifying such deposits comes from the complexity and uncertainties of classical definitions. For example, defining an orogenic gold system requires a previous definition of the regional geotectonic setting. Although a correct categorization of AFGP mineral deposits may be fundamental for both scientific and industry communities, it should be considered that currently known deposit models may not meet particular characteristics and features of the AFGP. Thus, the need to use current models may be hindering the identification of new gold deposit types at the AFGP. The Juruena-Teles Pires Mineral Province (JTPMP) is located at the southern border of the Amazonian Craton. This region experienced three main magmatic events: (1) 1.99-1.93 Ga metamorphic and granitic basement composed of highly deformed metamorphic rocks and felsic intrusions; (2) ca 1.87 Ga granitic and basaltic magmatism; and (3) 1.82-1.70 felsic and mafic volcanic-plutonic magmatism (Figure 2). A high-grade metamorphic

Colider Group (1.82-1.77 Ga) Riolite, dacite, ignimbrite and epiclas c rocks

data-point error ellipses are 68.3% conf.

Juruena Suite (1.82-1.75 Ga) Syenogranite, bt monzogranite, foliated granite, porﬁri c bt monzogranite

206

Pb/238U

Number

5. Teles Pires Suite (1.81-1.75 Ga) Alcali-feldspar granite to granodiorite, monzonite and monzodiorite

1900

0.34 1800 1700

Intercepts at 72 - 130 & 1818-6 [-9]Ma MSWD = 1.2

1600 0.26

0.22 3.5

4.5

207

Pb/235U

5.5

6.5

7.5

2640 2

1957

1500

1700

1900

2100

2300

2500

2700

2900

Idade 207Pb / 206Pb U-Pb data of zircon from sedimentary-derived migmatite. The migmatization age is indicated by the upper intercept of 1818 Ma, constructed with analysis of spots located on rims.

3. Flor da Serra Suite Gabbro, monzogabbro and diabase

0.35

1800

2. Matupá Suite (1.87 Ga) Mozonite and granodiorite syenogranite and monzogranite

2000

0.30

1600 1400

0.25

1200

206

2.00-1.93 Ga Orthogneissic and grani c basement

2100

0.38

Nova Monte Verde Complex Orthoderived Unit (1.80-1.78 Ga) Tonali c/granodiori c migma te Paraderived Unit (1.81 Ga) aluminous migma te

TL-14 Leucossome

0.46

0.42

4. Vespor Suite (1.77-1.76 Ga) Gabbro and amphibolite

1876

Pb /

~1.87 Ga Grani c and basal c magma sm

Beneﬁcente Group (1.75-1.70 Ga) Arenite, sil te, argilite and limestone

238

1.82-1.70 Ga Rondônia-Juruena Province. High-grade metamorphic rocks, felsic magma sm and sedimenta on

The Colíder Group is a high-K, calc-alkaline, meta- to peraluminous, acidic volcanic event, composed mainly of rhyolite, dacite, andesite and pyroclastic rocks (ignimbrite, tuff). Compiled ages from the Colíder Group indicate a magmatic activity between 1.82-1.77 Ga (U-Pb). The Sm-Nd data reveal model ages ranging between 2.8-1.8 Ga with ƐNd(t) between +5.45 and -3.06, indicative of the heterogeneity of the magmatic source with contribution of both the mantle and the crust. The Teles Pires Suite is composed of alkali-feldspar granite, syenogranite, monzogranite, monzonite and granophyre, showing mixing textures such as

Relative probability

core complex, composed by metasedimentary and meta-igneous units (upper amphibolite to granulite facies) were also formed during the third event (Figure 3). The Beneficent Group overlies all units and is characterized by a sedimentary rift sequence composed of arenite and pelite intruded by mafic and felsic rocks (1.5-1.4 Ga).

1000 0.15

1. Nhandu Suite (1.99-1.93 Ga) Syenogranite, monzogranite and granodiorite

800

Intercepts at 20±42 & 1763±6 [±8]Ma MSWD = 2.7

600

Cuiú-Cuiú Complex (2.00 Ga) Granodiori c orthogneiss and migma c tonalites

0.05

0.5

1.5

2.5

3.5

4.5

5.5

Paleossome age of the Monte Verde complex

Figure 02 - Stratigraphic column of the units in the studied area and the diﬀerent types of intrusions.

Figure 03 - Concordia plot for analyzes performed on rims and homogeneous zircon from of leucosome. The upper intercept is interpreted as the age of migmatization.

rapakivi and mafic and felsic fine-grained enclaves. The crystallization ages range between 1.81-1.75 Ga (U-Pb) and Sm-Nd model ages between 2.4-1.94 Ga with ƐNd(t) between +3.0 and – 3.4, suggesting the same conditions of formation as for the Colíder Group.

transtensional faults (Figure 4 and 5). Most of the veins are up to 3-m thick and several tens of meters long (Paraíba deposit – Peixoto de Azevedo). The mineralization also occurs as disseminated sulfides within hydrothermal alteration zones in volcanic and granitic rocks (Figure 6). The hydrothermal alteration in mineralized zones at almost all deposits is mainly phyllic, containing sericite, quartz and pyrite. In many cases, there are more distal zones represented by propylitic alteration haloes with epidote and chlorite. Potassic alteration (K-feldspar) is in general a barren zone. Quartz Au vein mineralization with fluid inclusion (<25% NaCl); and CO2 rich, frequently shows spiky high gold always hosted by pyrite-rich phyllic alteration. Phyllic alteration is carbonate-rich. Disseminated gold mineralization from Alta Floresta region is spatially and genetically related to acid porphyritic dykes and small plugs. This intrusive rocks display granophyric texture indicate that their emplacement occurred at shallow crustal levels

Assis (2015) dated the mineralization from three gold deposits located in the eastern part of the Juruena-Teles Pires Mineral Province: (1) Pé Quente (Re-Os in pyrite) – 1.792±9 Ma to 1.784±11 Ma; (2) Luizão (Re-Os in pyrite) – 1.790±9 Ma to 1.782±9 Ma; and (3) X1 (Re-Os in molybdenite) – 1,787±7 Ma to 1.785±5 Ma. The results yield an isochron of 1.786±1 Ma, which is interpreted as the age of a single mineralizing event for these three gold deposits (Assis, 2015). These results corroborate with the ages obtained for porphyritic granite bodies (União do Norte porphyry: Assis, 2015; Miguel-Jr, 2011) that has being interpreted as the mineralizing agent. Some authors do not discard the possibility of more than one mineralizing event at the JTPMP, with this province being considered as the counterpart of the Tapajós Mineral Province northwards (separated by the Cachimbo graben), and whose isotopic data suggest an age of 1.87 Ga for the mineralizing event.

The figure 7 shows that the Colider magmatism, responsible for the gold mineralization, took place simultaneously to the neosome formation of the migmatites and mafic magmatism, corroborating its intraplate signature (Rizzotto et al., 2016). This is in accordance to the previous proposal for the gold mineralization origin in the AFGP (Teixeira et al., 2015).

In the Alta Floresta region, the gold mineralization shows the same characteristics of those in the Tapajós area, except by slightly younger ages. There are two main types of gold mineralization in the Alta Floresta area: (1) Small disseminated and structurally-controlled Au ± Cu -(Bi, Te, Ag, Mo) deposits associated to pervasive silicification and sulphidation; and (2) Structurally-controlled veintype Au + Zn + Pb ± Cu deposits. Both deposit types are hosted by granites (Assis 2015). Additionally, Serrinha and Juruena deposits have been considered as porphyry type (Abrão), sited in volcanic arc setting. The gold mineralization in the province is located in transtensional faults and shear zones of ductile-brittle behavior (Figure 1b). Most of the deposits are hosted in quartz veins and veinlets cutting granite bodies and volcanic rocks. The shapes of the ore-bodies are variable, but they are pyrite, chalcopyrite and/or galena-bearing quartz veins with gold concentrated in dilatational fault jogs or

There are also copper and base metals occurrences in the province. One of the most famous deposits is Aripuanã, which consists of a Zn-Pb-Ag-Cu-Au deposit hosted by felsic volcanic rocks of Roosevelt Group, the Colíder Group counterpart southwards. This deposit is being developed by Votorantim Metais and there is a real potential of new discoveries in the region. Another known deposit of Pb-Zn with gold is the Francisco deposit, nearby the União do Norte village, in the region of Peixoto de Azevedo, and there is also a base-metals exploration target named “Guarantã Ridge” that is in the preliminary studies phase. Although no viable copper deposits have been discovered until now, at the Serrinha de Guarantã target, previously explored by Rio Novo Gold, a drill-hole intercepted 45m at 0.5% Cu.

N10°E/80°SW Crentes

N55°E/60°SE D.Maria

N σ1

σ1 ~ N-S

σ3 σ3

T σ1 Figure 04 - (A) Structural model of the shear zone identified on the Crentes and Dona Maria deposits. (B) (C) (E) Shear zone filled by quartz and sulfide and extensional veins filled by drusiform quartz. (D) Riedel scheme showing σ1 and σ3 vectors directions.

Veins

Tension Gashes

s1 ~N-S

°SE

/80

°E N50

Tension Gashes

Figure 05 - Geometric interpretation of the shear zone identiﬁed on the Cajueiro Project. Tension gashes with N-S direction ﬁlled by quartz and kaolin setting up a sinistral shear zone (σ1 = NNE-SSW).

Figure 06 - The Peixoto de Azevedo gold district. (A) Banded quartz vein, alterna ng quartz bands with chlorite and sulfides bands – Serrinha do Gurantã gold deposit sha . (B) Free gold in rusty sulfide rich quartz vein – Valen m deposit. (C) Quartz vein with chlorite and pyrite bands. (D) Vein samples from Serrinha do Gurantã deposit, copper sulfide rich (bornite and chalcocite) and secondary copper minerals (malachite, azurite and chrysocolla). (E) X1 Deposit: Disseminated pyrite (blue circles) in granite with phyllic altera on. (F) Gurantã Ridge Deposit: hydrothermal breccia with venules filled by galena and disseminated thin chalcopyrite.

Francisco e Bigode

Phyllic

Gold Disseminated Pé Quente Serrinha X1

Paraiba

Alta Floresta

Mineralization 1.78 Ga Assis (2015)

B 1760 -1750 Ma 1813 - 1763 Ma

Sintectonic Granites

1810 - 1780 Ma

1813-1763 Ma

Dikes Neossome

Migma tes / Granulites Paleosome MASH

MASH

1818-1763 Ma

Adapted from Rizzo o et al., 2016

Figure 07 - (A) The Alta Floresta gold deposits have the following characteris cs: (1) Disseminated gold in phyllic altera on zones, associated to acid subvolcanic dykes and plugs; (2) Massive quartz veins and stockworks with epizonal to mesozonal tectonic fabrics and restrict wall rock altera on (± adularia, sericite, k-feldspar, chlorite); and (3) Spa al and temporal associa on to post-tectonic granites. Note that the União do Norte, X1, Pé Quente gold deposit are related to phorphyry rocks and phyllic altera on zone. (B) Vuggy quartz vein. (C) The cartoon shows an extensional environment and an underpla ng development genera ng felsic magmas (1.82-1.70 Ga). The migma tes neossome ages are coincident with the volcanic and subvolcanic (1.82-1.77 Ga) rocks related to the gold mineraliza on (1.78 Ga). Fluids responsible for gold and polymetallic deposits of the Alta Floresta were exsolved from underplate magmas on a ri ed cratonic margin, more probably associated to mantle upwelling than to slab subduc on.

NOTE: The informa on provided here and which may not be part of the SGB-CPRM project is the sole responsibility of the reviewers

References ASSIS, R.R. 2015. Depósitos auríferos associados ao magmatismo félsico da Provincia de Alta Floresta (MT), Craton Amazonico: Litogeoquímica, idade das mineralizações e fonte dos fluidos. Tese de Doutorado. Instituto de Geociências, Universidade de Campinas, Campinas, 363 p.; MIGUEL-JR, E. Controle estrutural das mineralizações auríferas e idades U-Pb das rochas encaixantes ao longo do Lineamento Peru-Trairão: Província Aurífera de Alta Floresta, Mato Grosso. Dissertação de Mestrado. Instituto de Geociências, Universidade de Campinas, Campinas, 2011. MOURA, M. A 1998. O maciço granítico Matupá e os depósitos de ouro Serrinha (MT): petrologia, alteração hidrotermal e metalogenia. Tese de Doutorado.

Brasília, UnB, 238p. ;MOURA M.A. & BOTELHO N.F. 2002. Petrologia do magmatismo associado a mineralização do tipo ouro pórfiro da província aurífera Juruena-Teles Pires (MT). Revista Brasileira de Geociências, 32(3):377386.; RIZZOTTO, G. J. Significado Tectônico das rochas de alto grau do norte do Mato Grosso. In: CONGRESSO BRASILEIRO DE GEOLOGIA, 48, 2016, Porto Alegre - RS. Anais. São Paulo - SP: Sociedade Brasileira de Geologia, 2016.; XAVIER, R. P.; ASSIS, R. R.; CREASER, R.; TREVISAN, V. G.; PAES DE BARROS, A.J; AZEVEDO, A.; MIGUEL-JR, E.; BARROS, M. A. S.; PINHO, F. E. C. 2013. Timing of gold metallogeny in the Alta Floresta Gold Province: evidence from pyrite and molybdenite Re-Os isotopic dating. In: 13° Simpósio de Geologia da Amazônia, 2013, Belém (PA).

Seridó Project

Alan Costa, Alexandre Dantas, André Cunha, André Spisila, Rogério Cavalcante, Rafael Bi encourt Lima.

The Borborema Province is a poly-deformed Neoproterozoic Brasiliano/Pan-African belt, within northeastern Brazil, that cover a total area of over 450,000 km2. It is situated to the North of the Archean-Paleoproterozoic São Francisco Craton. Its architecture results from a diachronic collage of Archean nuclei, Paleoproterozoic terranes and Tonian-Ediacaran belts during the closure of western Gondwana, and it is enclosed between São Luis/West African and São Francisco/Congo cratons (Brito Neves et.al., 2000). It is distributed in ﬁve large domains or terranes (Médio-Coreau, Ceará Central, Rio Grande do Norte, Zona Transversal and Meridional domains),

which are separated by deep transcurrent shear zones: Transbrasiliano, Senador Pompeu, Patos and Pernambuco. An Archean/ Paleoproterozoic basement is recognized northward of the Patos shear zone, while Tonian-Ediacaran belts predominate in the Transversal and Southern domains. The Seridó Mineral Province is part of the Rio PiranhasSeridó subprovince (PSD on ﬁgure 1) of the Rio Grande do Norte Domain. It hosts historical tungsten mines back to the 1940´s, some s ll in produc on, and more recent gold and iron ore mines. It has a great diversity of mineral deposits (Au, W, Fe, Nb, Ta, Mo, kaolim) and 36oW

38oW

Potiguar Basin

300

Natal

6oS

2000

1000

JCD

200

PSD

João Pessoa

ZTD

? ?

8oS

Recife

4 PAD Modified from Medeiros (2011)

LEGEND

Transcurrent Shear Zones Phanerozoic Cover Depth (meters) Brasiliano Granitoids 1) Patos 2) Picuí-João Câmara, City JD - Jaguaribeano Domain 3) Portalegre 4) Pernambuco PSD - Rio Piranhas-Seridó Domain Project Area JCD - São José do Campestre Domain 0 25 ZTD - Zona Transversal Domain PAD - Pernambuco-Alagoas Domain Figure 01 - Loca on of Seridó Mineral Province in the geological and metalogene c context of Borborema Province. Adapted from Medeiros et al. (2011).

50km

gemstones, mostly explored by ar sanal prospectors or small-cap mining companies.

the mineralized BIF of Saquinho Fe mine. The Jucurutu Forma on is successively overlaid by a carbonate pla orm and siliciclas c rocks of the Equador forma on, both being overlapped by the turbidite-ﬂyschoid sequence of the upper and extensive Seridó Forma on.

The Geological Survey of Brazil (CPRM) is currently carrying out the Seridó Project, which aims to provide a geological-geophysical integra on map of the SMP and a semi-regional geochemical survey on ﬁ een 1:100,000 sheets. In more detail (1:50.000), the Seridó project is mapping the meta volcanosedimentary Jucurutu Forma on, which hosts most of the W and Fe occurrences in the province, alongside with detailed studies of the main mineral deposits (W: Brejuí and Bodó; Au: São Francisco, Bonﬁm; Fe: Saquinho).

Plutonism related to the Brasiliano Event (Ediacaran age) intrudes all the Seridó units. Its main episode was dated between 580-550 Ma and is represented by the extensive porphyri c high-K calc-alkaline Itaporanga suite and other minor plutonic rocks. Furthermore, isotropic grani c bodies of nondetermined chemistry and late orogenic pegma c dykes were dated between 514-509 Ma.

Figure 1 shows the limits of the ﬁ een sheets mapped by CPRM at 1:100.000 scale that encompass the Seridó Mineral Province. The western Jaguaribe Domain (JD) is bordered by the Portalegre Shear Zone (3), and the eastern São José do Campestre Domain (JCD) is bounded by the PicuíJoão Câmara Shear Zone (2). Between them lies is the central Rio Piranhas-Seridó Domain (PSD). The southern Zona Transversal Domain (ZTD) is limited by the Patos (1) and Pernambuco (4) shear zones.

The most signiﬁca ve W occurrences at Seridó Mineral Province are charaterized, at the airborne magne c maps (Figure 2), as shallow anomalies, coincident with nega ve gravimetric anomalies. It is interpreted to depict a series of structurally controlled grani c intrusions (Itaporanga suite), that when interact with the metasedimentary Seridó Group forma ons forms a rheological and chemical interface favorable to W concentra ons. The gammaspectrometric survey (Figure 3) iden ﬁed strong potassium anomalies correlated with the major W deposits, and a discon nuous potassium anomaly along the second-order structure of São Francisco Shear Zone, where is located the São Francisco gold deposit. As expected, the Saquinho Fe deposit is correlated to posi ve gravimetric and magne c anomalies.

The poorly explored São José do Campestre Domain is characterized by smooth relief and scarce outcrops. It has preserved a Palaeo-to-Neoarchean block, named as Núcleo Bom Jesus - Presidente Juscelino (Bizzi et al., 2001), surrounded by aglu nated Palaeoproterozoic migma zed units (Santa Cruz Complex). Entangled metaplutonic suites with TTG aﬃnity and some scarce and discon nuous metavolcanic and BIF (Algoma Type) are reported.

The SMP hosts over 700 skarn occurrences, some intermi ently since the 1940's explored for W-Mo (Brejuí, Bodó, Bonito, Malhada Limpa and Quixadá mines), gold (Itajuba ba mine) and gold with associated W-Mo-Bi-Te (Bonﬁm mine). The main deposits are Brejuí, containing 11 Mt of WO3 (remaining 5.5 Mt at 0.5-1.0% WO3), and Bodó, containing 9 Mt at 2% of WO3.

The Rio Piranhas-Seridó Domain is composed of a Siderian/Rhyacian/Orosirian basement (Arabia and Caicó complexes) with scarce Archean relics and supracrustals rocks of the Ediacaran Seridó Group. The Arabia complex is mostly composed of orthoderived metaplutonic units. The Caicó complex is a heterogeneous, polydeformed and widely migma zed gneiss with meta volcano-sedimentary and metaplutonic protholites. Recent geophysical survey and ﬁeld inves ga on have iden ﬁed kimberlite intrusions hosted by the Arabia complex in the northwest of the city of Lages, in Rio Grande do Norte State (Cabral Neto et. al., 2015).

The iron deposits are magne te-hema te bearing deposits, with grades up to 60% Fe, but commonly around 43% Fe, with the major body (Saquinho iron mine) containing 38Mt@55%Fe (Santos et al, 2014). The gold deposits mineralogy comprises sulphides and oxides, with a paragene c associa on of pyritechalcopyrite, pyrrho te, magne te and ilmenite. In the São Francisco deposit, galena, Ag-arsenopyrite and molybdenite are reported. Gold grades are up to 30 g/t, but usually in the range of 1-5 g/t. Total reserves, based on a cut-oﬀ grade of 0.25 g/t Au, are

The Seridó Group consists of low-to-medium grade metasediments, with the basal Jucurutu forma on locally composed by discon nuous volcanosedimentary sequences, and in which it is included

36°45'W

36°15'W

35°45'W

5°45'S

37°15'W

37°45'W

Au-W

6°15'S

W Au Fe

7°15'S

6°45'S

Mineral deposits

40km

Figure 02 - Reduced to the pole magnetic map of Seridó Project. The interpretation of the magnetic alignments indicates the predominance of the directions between 90ºAz and 45ºAz, with a lower frequency of alignments between 270º AZ and 290º Az. 36°45'W

36°15'W

35°45'W

5°45'S

37°15'W

37°45'W

Au-W

6°15'S

W Au Fe

6°45'S

7°15'S

Mineral deposits

40km

Figure 03 - Ternary gammaespectrometric map of Seridó Project. The high K contents are mainly related to intrusions of granites and Neoproterozoic pegmatites, which hosts gemstones, kaolim and wolframite mineralization.

up to 10,890t @ 0.91 g/t Au, reaching 318 ounces of gold (Aura Minerals on-line report, 2011)

Caicó complex. Polymetallic sulphides are reported but their poten al remains unexplored.

The tungsten (W) deposits are spa ally related to the Itaporanga high-K calc-alkaline suite, with an extensive skarn altera on along rheological contras ng contacts, with the main mineralized bodies occurring in a stratabound style over marble layers of the Jucurutu forma on (Figure 4). Locally, skarniﬁca on occurs also inside the granite as an endoskarn (reported in the Bodó and Itajuba ba mines), and in the basal sheared contact with the

The ore shows evidence of high-temperature calcic altera on (up to 650 C) forming anhydrous calc-silicate mineralogy (diopside, andradite, wollastonite) followed by medium-temperature altera on to a hydrated silicate mineralogy (hornblende, vesuvianite, escapolite, epidote, ac nolite, grunerite), with scheelite and sulphides disseminated. Carbonate veins and cavi es ﬁlled with sericite, zeolite, limonite and powdery scheelite indicate the recurrent altera on by

FBM-05 FBM-08 550

BDM-04

Altitude (m)

BDM-03

500

450

400

LEGEND Soil Pegmatites Calc-silicates rocks Biotite granite

Foliation

Granite alteration halo Jucurutu Fm.: (a) Magnetite bearing biotite gneiss

BDM-03

Drillholes

(b) Marble lenses

50m

Horizontal Scale

Figure 04 – Ver cal Sec on E-W 01 of the Bodó tungsten mine.

ﬂuids progressively evolving to lower temperature (Figure 5).

The gold (Au) deposits (São Francisco, Simpa co, Ponta da Serra, São Fernando, Bonﬁm) are lode-gold deposits related to high-angle shear zones which cut the Neoproterozoic (Seridó Group) and the Palaeoproterozoic rocks (basement gneisses), ac ve during the late deforma on event (that took place between 520-500 My ago, from 40Ar/39Ar data in mica, Araújo 2001), similar to other orogenic-gold models. The basement of Bonﬁm gold deposit, located northern of the São Francisco fault, yielded Archean age (3,508Ma U-Pb in zircon, Velásquez, et.al., 2016), suggest that Archean inliers bellow the São Francisco Shear Zone may have contributed to the gold mineraliza on.

In the iron (Fe) deposits (Saquinho, Serra da Formiga, Bonito, Serra do Fei ceiro, Riacho Fundo and Serra dos Quintos), the magne te-hema te bearing BIF occurs at the base of Jucurutu forma on (Figure 6), associated with maﬁc volcanics. Some geochemical features (Chromium, Cerium, REE and Europium anomalies) suggest volcanic input to the forma on of the deposits (“Algoma-like”), although stable and 13 radiogenic and isotopes inves ga ons (nega ve δ C and 87Sr/86Sr) suggest glacial inﬂuence on the site of iron deposi on (“Rapitan-like”) (Sial et al., 2015).

Bodó Mine - High grade ore. Scheelite bearing veins and disseminated scheelite in epidote-diopside skarn. Scale: 15x23cm. Mineral abbrevia ons according to Whitney & Evans, 2010: Sch - Scheelite, Di - Diopside, Ep - Epidote, Grt - Garnet, Ves - Vesuvianite

Brejui Mine - Epidote-diopside skarn cross-cu ed by molybdenite veinlet associated with par ally ﬁlled cavity with carbonate, zeolite, limonite and powdery scheelite Mineral abbrevia ons according to Whitney & Evans, 2010: Sch - Scheelite, Zeo - Zeolite, Cb - Carbonate, Mol - Molybdenite

Figure 05 – Photographs of diﬀerent aspects of the tungsten ore at the Bodó and Brejuí mines.

Schematic Section (around 580-520My)

Paleo -proterozoic

Neo -proterozoic

Schematic Stratigraphy

Brasiliano Plutonics (590 - 540 Ma) Granitoids Jucurutu Fm. (630 - 600Ma) Biotite (amphibole) paragneiss partially epidotized Banded Iron Formation (Rapitan type ?) Amphibole-biotite schist with garnet Marble Banded Iron Formation interlayered with garnet amphibolite Rhyacian Augen Gneiss (2.171 Ma)

Archean

Deformed supracrustals Amphibole-Biotite augen gneiss Archean (2.512 Ma) Banded Iron Formation (Algoma type) Metaultramafic with mafic subordinated Chlorite-biotite schist interlayered with quartz-feldspar mylonite Felsic mylonitic gneiss (some volcanogenic?) Amphibole-Biotite mylonitic tonalitic gneiss

Figure 06 - Schema c Sec on and idealized stra graphy of the of the basal units of the Jucurutu forma on around 580-520Ma.

References Araújo, M.N.C., 2001. A cinemá ca superposta e as mineralizações auríferas da Faixa Seridó: uma abordagem meso e microscópica. Tese de Doutorado, IG/UFRN, 256 p; Aura Minerals report 2011, available in: h p://www.auraminerals.com/ Opera ons/Sao-Francisco/Reserves-and-Resources/default.aspx. Date of access 02/10/2017; Bizzi, L.A., Schobbenhaus, C., Gonçalves, J.H., Baars, F.J., Delgado, I.M., Abram, M.B., Leão Neto, R., Matos, G.M.M., Santos, J.O.S., 2001. Geologia, Tectônica e Recursos Minerais do Brasil. Sistema de Informações Geográﬁcas - SIG e mapas na escala de 1:250.000.000. CPRM, Editora da Universidade de Brasília, Brasília, CD-ROM; Brito Neves, B.B., Santos, E.J., Van Schmus, W.R., 2000. Tectonic history of the Borborema Province, Northeastern Brazil. In: Cordani, U., Milani, E., Thomaz Filho, A., Campos, D.A. (eds) Tectonic Evolu on of South America. Special Publica on, 31st Interna onal Geological Congress, Rio de Janeiro, Brazil, pp 151182; Cabral Neto, I., Cunha, L.M., Silveira, F.V., Oliveira, R.G., Souza, W.S., Bezerra, A.K., 2015. Registro dos primeiros corpos com aﬁnidade kimberlí ca na Província Borborema, NE do Brasil. Informe Técnico N2 ;Medeiros, V.C., Medeiros, W.E.,

Jardim de Sá, E.F., 2011. U lização de imagens aerogamaespectrométricas, landsat 7 ETM + e aeromagné cas no estudo do arcabouço crustal da porção central do domínio da zona transversal, província Borborema, NE do Brasil. Revista Brasileira de Geo sica 29, 83–97; Sial, A.N., Campos, M.S., Gaucher, C., Frei, R., Ferreira, V.P., Nascimento, R.C., Pimentel, M.M., Pereira, N.S., Rodler, A., 2015. Algoma-type Neoproterozoic BIFs and related marbles in the Seridó Belt (NE Brazil): REE, C, O and Sr isotope evidence. Journal of South American Earth Sciences, pp 33-52; Santos, J.E., Souza Neto, J.A., Silva, M.R.R., Beurlen, H., Cavalcan , J.A.D., Silva, M.G., Dias, V;M., Costa, A.F., Santos, L.C.M.L., Santos, R.B., 2014. Metalogênese das porções norte e central da Província Borborema, in Silva, M.G., Rocha Neto, M.B., Jost, H., Kuymjian, R.M.(eds), CPRM, 2014, Velásquez, F., Della Gius na, M.E., Oliveira, C.G., Dantas, E.L., 2016. Lentes ultramáﬁcas paleoarqueanas na faixa Seridó, NE do Brasil: Evidencias de reequilíbrio de óxidos de Fe-Ti-V no Brasiliano. Anais do XLVIII Congresso Brasileiro de Geologia, Porto Alegre, Rio Grande do Sul.

NW Ceará Project Tercyo R G Pinéo, Alex Franca Lima, Mariane D Martins, Maria D M R Bessa

The Northwest of Ceará Project is part of the CPRM Program for Geological-Geophysical Integration and Predictive Prospectivity Mapping of the Brazilian Shields (Figures 01 and 02). The main objective of this project is to study the metallogenic potential and identify new mineral occurrences in the Martinópole Group, a Neoproterozoic meta-

volcano-sedimentary sequence which hosts polymetallic Cu-Pb-Zn sulfides, copper, iron ore, manganese and barite mineralization. The Granja Complex represents the basement of this supracrustal sequence and is composed of TTG orthogneisses, paragneisses and granulites of Paleoproterozoic age (2.3 Ga) (Santos, 1999).

-41°00'

-40°30'

Granja

Martinopole

Uruoca

3°30'

2 Vicosa do Ceara

Sobral

Fault

20km

LITHOSTRATIGRAPHIC UNITS PALEOGENE BARREIRAS GROUP Sandstones, conglomarates and laterites.

Metasandstones (Goiabeira Formation).Gray and blue Metamarbles (Frecheirinha Formation). Slate, phyllite and metasandstone (Caiçaras Formation). Quartzites and metasandstone (Trapiá Formation). MARTINÓPOLE GROUP Phyllites, marbles, quartzites, metacherts, metavulcanics, and BIF’s (Santa Terezinha Formation). Schists, phyllite, and BIF’s (Covão Formation). Quartzites with intercalation of schists, alc-silicate and BIF’s (São Joaquim Formation). Schists, quartzites, and paragneisses (Goiabeira Formation).

SILURIAN SERRA GRANDE GROUP Sandstones, siltites, argillites and conglomarates. CAMBRO-ORDOVICIAN

Conglomarate (Fazenda Fortaleza Formation).Sandstone, siltite and argillites (Morada Nova Formation). Polimitic Conglomerate (Barra do Sairi Formation).

Migmatitic paragneisses with lenses of quartzite, calc-silicate, marble, amphibolite, metavolcanics (700 Ma).

Polimitic Conglomerate (Aprazível Formation).Basalts and rhyolite (Parapuí Formation). Sandstone and siltite intercaleted (Pacujá Formation). Polimitic conglomerate (Massapê Formation). MERUOCA GRANITOIDS Batholiths ans stocks of red granites (532 Ma).

Metarhyolite, metabasalt, BIFs, calc-silicate, and volcanoclastic rocks (1785 Ma). FORQUILHA ORTHOGNEISSE Tonalitic to granodioritic orthogneisses with amphibolite enclaves (2049 Ma).

Brejinho Suite - Syenites and alkaline piroxenites (554 Ma).

Milonitic gneisses, paragneisses, metaultramafic rocks, marbles, amphibolite, and calc-silicate. Granitic to granodioritic orthogneisses intrusive (2100 Ma).

Tucunduba - Green Granite and granodiorite (574 Ma). Chaval Suite - Porfiritic monzogranite, granites, syenites (591 Ma).

Orthogneisses, migmatites, granulite gneisses, leucogneisses, calc-silicate, quartzite, paragneisses and amphibolite (2357 Ma).

Metatexites, diatexites, gneisses and porfiritic pink granites (650 Ma).

Figure 01 - Geological Map of project area.

The Martinópole Group is divided in four lithological formations (Figure 03) deposited on a passive continental margin between 800-750 Ma (Santos, 1999) and later deformed by the Brazilian/PanAfrican orogeny (~600 Ma), with low- to medium grade metamorphism (from greenschist to amphibolite facies) (Figure 04). The base of the Martinópole Group is the Goiabeira Formation, which consists of schists, quartzites and paragneisses. The overlapped São Joaquim Formation is composed by quartzites. The upper Covão Formation comprises schists and phyllites, while the top unit corresponds to the Santa Terezinha Formation, with phyllites, carbonate phyllites, marbles, quartzites, meta-cherts, calcsilicatic rocks, BIFs, and meta-volcanic rocks, dated by zircon U-Pb at 800 Ma (crystallization age). This uppermost formation hosts distinct deposits and mineral occurrences, especially copper, lead, zinc, manganese and iron, which are grouped into three separate targets: Uruoca Target, Pedra Verde Mine and Serra de São José Target (Figure 05).

The Uruoca Target, worked by CPRM during the 1980´s, is composed of phyllites and quartzites with milonitic structure, metachert, hydrothermal breccia, meta-rhyodacite, and laterite covers. The metachert contains levels of manganese-iron oxide and minor widespread crystals of bornite and pyrite. The hydrothermal breccia has common boxwork texture and is distributed along a NE-SW shear zone (Figure 06). The manganese mineralization at Uruoca is associated to laterites aligned NE-SW, with hydroxide, iron hydroxide, hematite, magnetite and quartz fragments also within a boxwork texture. The presence of manganese layers and phyllites, both intercalated and folded, suggests a syngenetic occurrence with superimposed weathering processes. Chalcopyrite, pyrite, bornite, sphalerite and galena in fractures and also in veins of metacarbonate rocks (marbles, carbonatic phyllites, and calc-silicatic rocks) associated with meta-acid volcanic rocks were described from boreholes samples (Prado et al., 1980).

-41º

-40º 30'

Martinópole

Uruoca Target

Uruoca

-3º 30' 488 125

Viçosa do Ceará

Sobral

nT 33

-270

Figure 02 - Magnetic map reduced to pole that represent the superposition of magnetics fonts to depth from 1km to 2km. Penetrative magnetic lineaments are marked by black lines.

MARTINÓPOLE GROUP

808Ma

Formations BIF’s Calc-silicate

Santa Terezinha

Metafelsic Metacherts

Passive Margin 800 - 750 Ma

Santa Quitéria Arch 660-630 Ma Troiá Massif Ceará Complex Greestone belt Backarc (750 Ma)

Martinopóle Group

Canindé do Ceará Basement

Granja Complex Basement

Phyllite

Covão Continental collision Cu-Co-Ba-BIF 620-615 Ma Zn-Pb Syn-Orogenic Post-Orogenic 590 Ma 520 Ma 3 1 UHP 2

Calc-silicate

Cr-PGE Troia Massif

4 530-480 Ma

São Joaquim

Quartzites

2.1 Ga

480 Ma TTG 3,5-2,7 Ga

Post-Colisional

Paragneisses Quartzites

2300Ma

1 - Cu-Co Pedra Verde 2 - Cu-Fe Jaíbaras 3 - Au Rerituba

Schists Granja Complex

4 - Fe Santa Quitéria 5 - Ti Independência

6 - Cr-PGE Tróia 7 - Au Pedra Branca

Figure 04 - Geodinamic model to the northwest Ceará, from passive margin to continental collision, involving Médio Coreaú and Ceará Central terrains. Highlight for the Martinópole Group.

Figure 03 - Lithostratigraphic column of the Martinópole Group.

Modified from Araujo (2014).

Pedra Verde/Serra de São José Region

Uruoca Region

LITHOSTRATIGRAPHIC UNITS PALEOGENE

Ceará Central Domain

Médio Coreaú Domain

Goibeira

Serra Grande Group

Barreiras Group NEOPROTEROZOIC CAMBRO-ORDOVICIAN Riacho Sairi Group

( (

) PALEOPROTEROZOIC

Figura 05 - Geological maps of prospecting targets.

)

Normal fault Syncline Shear zone

Mn+Fe B

Figure 06 - Pictures of Uruoca Target: A) Metachert with iron-copper sulfide and levels of Fe-Mn oxides. B) Hydrothermal breccia (manganese, iron, and quartz).

During the 1980´s, a small copper mine operated at the region, the Pedra Verde mine. Located on a NESW shear zone that is marked by one staggered magnetic lineament, the host rocks are altered phyllite transiting to carbonated phyllite. The altered phyllite is 22 m thick and contains malachite and azurite as main secondary copper minerals

(Figure 07). The ore is zoned and marked by chalcocite-bornite-chalcopyrite-pyrite-galenasphalerite (Collins and Loureiro, 1971). The sulfides occur in two distinct ways: deformed along the milonitic foliation of the host carbonatic phyllite, and along carbonate veins indicating a hydrothermal concentration (Matos, 2012).

Phyllite carbonated with pyrite in carbonate veins

Figure 07- Pictures of Pedra Verde Mine: A) Sample od phyllite carbonated from borehole showing carbonate veins with sulfide. B)Malachite leaching on outcrop of phyllite carbonate.

The Serra de São José target has barite with associated Ni (500 ppm) and Co (500 ppm) anomalies in folded BIFs (Figure 08). Local geology comprises marbles, phyllites, schists, metagreywackes, meta-cherts and BIFs (Prado et al., 1979). Geophysical data indicates the possible continuity of the target underneath the Silurian sediments of the Parnaíba Basin.

Field observations and compiled data from the limited literature available indicate the potential for SEDEX-type deposits, formed on a passive continental margin between 800-750 Ma (Figure 09), followed by hydrothermal reconcentration along the NE-SW structures, during the Brasiliano/Pan-African Orogeny (~600 Ma).

Figure 08 - Pictures of Serra de São José Target: A) Folded Banded Iron Formation. B) Detail of BIF.

Serra de São José Target Fe (BIF), Co-anomaly

sea level

Pedra Verde Mine Pelite Cu, Pb, Zn carbonated

10 km

~ ~ ~ ~ ~. . . . . . . . . .

. . . .. .

Slope and abyssal sediments Ubajara Group Pelites, marbles, psamites Martinópole Group ~ ~ Santa Terezinha Formation: pelites

. .

~ . .

~ ~ .

. .

Pelite carbonated Acid volcanic

~. . .

. .

. . . .

. .

. . . . . . . . . . . . .

. .

Basement

Carbonate rock

~ ~

~ .

Uruoca Target Cu, Pb, Zn, Mn, Fe

Covão Formation: pelites São Joaquim Formation: psamites Goabeira Formation: pelites, psamites Granja Complex Orthogneisses, migmatites, granulite gneisses. .. .. . .

Hydrotherma Fluid Flow Metal concentration (chemical Trap)

100 km

Figure 09 - Conceptual model of the geologic setting for SEDEX deposits modified from Emsbo (2009)

References ARAUJO, C.E.G. Evolução tectônica da margem ativa Neoproterozoica do Orógeno Gondwana Oeste na Província Borborema (NE-Brasil). Tese de Doutorado. Universidade de São Paulo. USP. 2014. EMSBO, P. Geologic criteria for the assessment of sedimentary exhalative (sedex) Zn-Pb-Ag deposits: U.S. Geological Survey Open-File Report 2009-1209, 21p. 2009 COLLINS, J.J.; LOUREIRO, A.R. A Metamorphosed Desposit of Precambrian Supergene Copper. Economic Geology. 66: 192-199. 1971. MATOS, J.H.S.N. Evolução Metalogenética da Mina de Cobre Pedra Verde (CE). 107p. Dissertação (Mestrado em Geologia e Recursos Naturais) – Instituto de Geociências, Universidade Estadual de Campinas, São Paulo. 2012.

PRADO, F.S., MENDONÇA, J.C.G.S., MORAIS, J.B.A., MEDEITOS, M.F., ASSUNÇÃO, P.R., ANDRADE, V.A., MEDEIROS, R.P. Projeto Martinópole. Relatório Final. Volume I. Companhia de Pesquisa de Recursos Minerais – CPRM. 1979. PRADO, F.S., SCHEID, C., SILVA, S.M.P., MEDEIROS, M.F., MELO, F. Projeto Uruoca: Relatório preliminar de pesquisa de cobre, chumbo e zinco nos municípios de Uruoca, Martinópole, Marco e Senador Sá – Estado do Ceará. Volume I, Texto e Mapas geológicos. Companhia de Pesquisa de Recursos Minerais – CPRM. 1980. SANTOS, T.J.S. Evolução tectônica e geocronológica do extremo nordeste da Província Borborema. Tese de Doutorado. Instituto de Geociências e ciências exatas. UNESP. 1999.

Gurupi Project

Leandro Duarte Campos, Sulsiene Machado de Souza, Diogo Alves de Sordi, Felipe Ma os Tavares, Evandro Luiz Klein, and Elem Cris na dos Santos Lopes.

The Gurupi Project is part of the program Mineral Poten al Assessment of the volcanic-sedimentary sequences of Brazil (Program III). The Project area sits on the borders of Pará and Maranhão states, north-northeast Brazil. Regionally the area is divided into two dis nct geotectonic compartments witch evolved during speciﬁc cycles, separated by more than 1,4, the São Luis cratonic 46°30'0"W

46°15'0"W

1°45'0"S

46°45'0"W

fragment (2695 to 2078 Ma) to the west-northwest, and the Gurupi orogenic Belt (980 to 591 Ma) to the east. The Gurupi Belt comprises Neoproterozoic sedimentary and intrusive igneous rocks. Its evolu on is related to west gondwana break-up and further inversion during mid- to late Neoproterozoic. Most of Neoproterozoic age rocks are es mated to be buried under the Paleozoic

Cachoeira do Piriá Boa Vista do Gurupi

2°0'0"S

L E G E N D Age (Ma)

2116-2078

2167-2148

2695

2°15'0"S

Phanerozoic Cover Neoproterozoic-Cambrian passive margin, orogeny and continental rift 591 Piriá Formation 624 Metamicrotonalite 980 Gurupi Group Syn-, late- and post-tectonic plutonic suites Biotite-muscovite granite, leucogranite and high-K granite Greenstone belt

3 Mafic metavolcanic, volcanoclastic and Iron formation Muscovite-quartz schist and quartzites Pre-tectonic plutonic suites Amphibolite Granite Gabbro, tonalite and granodiorite Orthognaisses and migmatites Basement Complex Igarapé Grande Metatonalite 46°45'0"W

8 km

5 46°30'0"W

Figure 01 - Gurupi orogen and Greenstone belt Chega-Tudo map. Adapted from Klein et. al., (2014)

46°15'0"W

Parnaiba Basin (Figure 01). In the Project area the Gurupi Belt is represented by meta-sediments of the Gurupi Group, the Caramujinho metamicrotonalite and the Piriá Forma on. The Gurupi Orogeny aﬀected the borders of the cratonic basement during the late Neoproterozoic. It is responsible for low-grade metamorphism, local hea ng and may be related to minor gold remobiliza on.

in South America a er the Atlan c break-up. It is formed by Paleoproterozoic volcanic-sedimentary sequences (greenstone belt) and plutonic suites developed in island-arc (and magma c arc?) environment (Figure 02 ). To this period are related: i) ultramafic flows (strongly carbonated talc schists), mafic and felsic flows (2160 to 2148 Ma), as well as volcanoclas c rocks from the Chega Tudo Forma on; ii) muscovite-quartz schists and quartzites from the Santa Luzia do Pará Forma on; and iii)clast-supported conglomerates and

The São Luis cratonic fragment represents an extension of the West Africa Craton that remained

Paleoproterozoic Island Arc (2240 - 2050 Ma)

Ocean Floor and Volcanic Arc

Parnaiba Block

São Luís West African Craton

Sta. Luzia do Pará Fm.

Peridotites,basalts, andesites, rhyolites and vulcanoclastics

Tromaí Suíte 2168 - 2148 Ma: tonalites, granodiorites e granites

Paleoproterozoic Arc Collision (2100 - 2080 Ma)

Orogenic Gold (Ashanti Type) Igarapé de Areia Fm.

Chega Tudo Fm. Parnaiba Block

São Luís West African Craton 2,69 Ga Tonalite 2,59 Ma Post-collisional Timbozal granite (2084 Ma)

Neoproterozoic Passive Margin (c. 980 Ma) Parnaiba Block

Negra Velha Suite 2056-2076 Ma

Sedimentary Phosfate

Sin-collisional Japiim granites (2100 Ma)

Gold Mineralization Aurizona

Tentugal Shear Zone Cipoeiro Fault

Gurupi Group and Cabeça de Porco Fm.

2240 Ma 2168-2148 Ma

Carbonic aqueous fluids of low to moderate salinity and deep origen (Klein et al., 2014)

Chega Tudo (Greenstone belt)

Neoproterozoic Orogeny (624 - 549 Ma)

32 Ton Au

Cipoeiro 52 Ton Au

Aurizona

65 Ton Au

< 1.140 Ma

Qz gold Veins

Au-Bi-As-Sb-Te

Sienite 732 Ma Nei Peixoto granite 549 Ma

Mineralitation´s age 1879-2000 Ma? Caramugim Metatonalite 624 Ma

Cloritization,carbonatatization, silicificationand sulphidation and graphite

kimberlites 340-370 C

Figure 02 - Geological evolution of the Gurupi orogen and Chega-Tudo greenstone belt. Gurupi orogeno evolved from a passive continental margin, while the vulcanosedimetary sequence would have an origin from island arc. Gold mineralization is restricted to Chega-Tudo greenstone belt. The gold sulphyde - graphitic quartz veins occur in ruptile and ductile shear zones.

quartzites (<2078 Ma) from the Igarapé de Area Forma on. These sequences were intruded by sintectonic bio te-muscovite leucogranites and posttectonic high K granites between (2116 and 2078 Ma). S ll in the Rhyacian, basin inversion (collision?) and amphibolite to upper-greenschist metamorphism were responsible for ﬂuid genera on, metallic extrac on, transport and deposi on, which resulted in an orogenic gold system hosted principally in the Chega Tudo and Igarapé de Areia forma ons. Chega Tudo, Santa Luzia do Pará and Igarapé de Areia forma ons, in addi on to the Rhyacian plutonic suites and Archean basement, compose the South American counterpart of the West Africa Craton´s Ashan Belt of Birimian age. Therefore, Both Chega Tudo and Igarapé de Areia forma ons can be compared to its African analogues from the Ashan Belt, the Sefwi and Tarkwan group respec vely, which is host to major gold deposits and a total endowment of ca. 125 Moz of gold.

carbonate, albite and sulﬁde minerals such as pyrite, arsenopyrite and rare chalcopyrite. Mineraliza on is concentrated within the Tentugal shear zone and its subsidiary branches. The Tentugal shear zone is contained by the Chega Tudo Fault to the west and by the Cipoeiro Fault to the east. The majority of gold occurrences and deposits are aligned along these faults, which were considered deep crustal faults a er magne c source modelling (Figures 3, 4 and 5). The Tentugal shear zone and its gold trends extends for more than 100 Km along strike and is es mated to con nue to north under CambrianPhanerozoic cover. Fluid inclusion and isotope studies indicate that gold deposits formed by lowsalinity, reduced aqueous- carbonic ﬂuid of metamorphic origin, opera ng between 260 and 380 °C and up to 3 Kbars (Klein 2014). The similarity between the mineraliza on of the Te n t u g a l s h e a r z o n e a n d t h e B i r r i m i a n mineraliza on is par cularly evident with the presence of graphi c material associated with the ore bodies.

Figure 03 - Analy c signal map of Gurupi.

Figure 04 - Colour composite (ternary) image over the Gurupi Project area.

2°0'0"S

Gold mineraliza on is host exclusively by the Rhyacian volcanic-sedimentary sequences and pre- tectonic plutonic suites. Gold occurs in disseminated sulﬁdes, quartz-sulﬁde crack-andseal shear veins and quartz stockwork zones

2°0'0"S

Gold mineraliza on is host exclusively by the Rhyacian volcanic-sedimentary sequences and pret e c t o n i c p l u t o n i c s u i t e s . G o l d o c c u rs i n disseminated sulﬁdes, quartz-sulﬁde crack-andseal shear veins and quartz stockwork zones related to bri le-duc le deforma on. Hydrothermal altera on is composed by quartz, chorite, sericite,

A Prophile 47°0'0"W

46°30'0"W

46°0'0"W

Depth (Km)

Chega Tudo Fault 6

20000

30000

40000

50000

60000

70000

80000

88833

Distance (m)

Chega Tudo Fault Legend Chega Tudo Fm. Igarapé de Areia Fm.

Collisional granites

Figure 05 - Simplified geological section. Deep structures were interpreted after magnetic source modeling. (A) Profile location over analytic signal map. (B) Magnetic source depths (red dots) and inferred structures. (C) Regional geological interpretation and location of Chega Tudo Fault.

related to bri le-duc le deforma on. Hydrothermal altera on is composed by quartz, chorite, sericite, carbonate, albite and sulﬁde minerals such as pyrite, arsenopyrite and rare chalcopyrite. Mineraliza on is concentrated within the Tentugal shear zone and its subsidiary branches. The Tentugal shear zone is contained by the Chega Tudo Fault to the west and by the Cipoeiro Fault to the east. The majority of gold occurrences and deposits are aligned along these faults, which were considered deep crustal faults a er magne c source modelling. The Tentugal shear zone and its gold trends extends for more

than 100 Km along strike and is es mated to con nue to north under Cambrian-Phanerozoic cover. Fluid inclusion and isotope studies indicate that gold deposits formed by lowsalinity, reduced aqueous- carbonic ﬂuid of metamorphic origin, opera ng between 260 and 380 °C and up to 3 Kbars (Klein 2014). The similarity between the mineraliza on of the Tentugal shear zone and the Birrimian mineraliza on is par cularly evident with the presence of graphi c material associated with the ore bodies. In Figure 06 new exploratory targets are presented.

Figure 06 - Final target map of the Gurupi Belt orogenic gold system. Regions with scores higher than 3 were considered most prospective and successfully predicted known deposits such as Cachoeira, Mina Nova Sul, Cachoeira, Chega Tudo and Cipoeiro. The target map was produced after combining evidential maps that reflected the understanding of the orogenic gold mineral system.

NOTE: The informa on provided here and which may not be part of the SGB-CPRM project is the sole responsibility of the reviewers

References: Klein, E. L. (2014). Ore ﬂuids of orogenic gold deposits of the Gurupi Belt, Brazil: A review of the physico-chemical proper es, sources, and mechanisms of Au transport and deposi on. In: P. S. Garofalo, J. R. Ridley (Eds.), Gold transpor ng hydrothermal ﬂuids in the Earths crust (pp. 121– 145). London: Geological Society, Special Publica ons 402.

Nova Brasilândia Project

Elias M G Prado, Anderson Souza, Guilherme I Tr Guerra, Gustavo N Bergami, Luciano C Silva, Thiago Reis Rodrigues.

The Nova Brasilândia Project is part of the Evalua on of Mineral Poten al of the Brazilian Volcano-Sedimentary Sequences Program. The areas are located at Rondônia State and were selected due the recent discovery of polymetallic sulﬁdes in the metasedimentary sequence of Migran nópolis Forma on, Nova Brasilândia Group (Figure 01).

Scandolara and Rizzo o (1994) as formed during the ri ing and opening of a narrow proto-ocean. The top sequence corresponds to the Migran nópolis Forma on and is composed by siliciclas c sediments with minor volcanic contribu on, including kyanite-staurolite gneiss, sillimanite-muscovite/bio te gneiss, muscovite/bio te-feldspar-quartz gneiss with lenses of hornblende-tremolite-garnet gneiss, fine-grained amphibolite, metagabbro sills and scarce metabasalts. The mineral assemblages of these rocks indicate upper amphibolite to granulite facies related to the closure of the basin. The rela onship between the meta-sediments and the mafic rocks, however, is s ll doubt, as a low angle tectonic affect all the units and mask the primary contacts. Also, due to the high

The Nova Brasilândia Group (NBG) is divided into the Rio Branco and the Migran nópolis forma ons (Scandolara and Rizzo o, 1994). The former comprises coarse and ﬁne-grained amphibolites, metagabbros, melagabbros and ga b b ro - n o r i t e s , i n t e c t o n i c c o n t a c t w i t h hornblende-tremolite-garnet gneisses. The Rio Branco Forma on represents a strong posi ve magne c anomaly. Those rocks are interpreted by 550000

600000

650000

700000

Paresis Basins

8700000

Quartenary Basins

LEGEND Quaternary Basins Parecis Basins (Neoproterozoic/Paleozoic) Meso-Neoproterozoic Basin Meso-Neoproterozoic Maﬁc lntrusions Stenian Syn- to Late-tectonic Granites Carbonate Mine Zn,Pb,Cu 1 Au Ar sanal Mine Cu Ar sanal Mine

Nova Brasilândia Basin (Mesoproterozoic) Migran nópolis Fm. Quar zites Amphibolites Paragneisses Schist’s Calc-silicates Zn,Pb,Cu d: Au Occurrence Cu Occurrence

Figure 01 - Geological map.

20km

Nova Brasilândia Basin (Mesoproterozoic) Rio Branco Fm Volcaninc and Plutonic Maﬁc Rocks with Cale-Silicate Lenses Ectasian Basement Calymmian Basement Thrust Fault Normal Fault Transpressional Shear Zone

8650000

Paresis Basins

complexity of the deforma on displayed by these rocks, only a schema cal stra graphic recons tu on is available (Figures 2 and 3). The deposi on of the Migran nópolis sediments occurred around 1215±20 Ma and the hypothesis for the geological se ng are an intracon nental ri or a passive margin of the Amazonian Craton (Rizzo o et al., 1999) (Figure 04). Aeromagne c anomalies suggest that the NBG sedimentary sequence is con nuous for at least 500 km in the E-W direc on, with the eastern area covered by Cretaceous sediments and the western part covered by Quaternary sediments (Figure 5) . Occurrences of Zn-Pb-Cu polymetallic sulﬁdes were iden ﬁed in areas prospected by Mineração

Santa Elina. The occurrences are characterized by strongly oxidized massive and disseminated sulfide zones (gossans at surface), iron oxide veinlets and stockworks, siliceous breccia and quartz veins. The Zn-Pb-Cu sulfide hydrothermal breccia and gossans are hosted by muscovitebio te-feldspar-quartz gneiss interlayered with sillimanite-bio te-muscovite gneiss, hornblende-tremolite-garnet gneiss (calcs i l i c a c ro c k s ) , fi n e - g ra i n e d a m p h i b o l i t e (metagabbro) and BIF. The massive sulfide zones occur as stra form mineralized lenses intercalated with sulfide-bearing muscovitebio te-feldspar-quartz gneiss. These polymetallic sulfide zones are 5 to 40 m thick and

Quaternary Basin Arenites, sil tes and argillites Parecis Basin Conglomerates, Arenites, and argillites Meso-Neoproterozoic Basin Meta-psamites and meta-pelites

Quaternary Basin Arenites, sil tes and argillites

Migran nópolis Fm.

Quartzite

Parecis Basin Conglomerates, Arenites, sil tes and argillites

Schist Paragneiss

Meso-Neoproterozoic Basin Meta-psamites and meta-pelites

Amphibolite lenses Schist

Migran nópolis Fm. Quartzite

Calc-silicate lenses

Schist Paragneisses and meta-conglomerates with cacl-silicate and amphibolite lenses Zn, Pb, Cu Ore

Paragneiss Zn, Pb, Cu Ore Meta-conglomerate Thrust fault Rio Branco Fm. Paragneisses

Thrust fault

Maﬁc Volcanics Calc-silicate lenses

Rio Branco Fm. Paragneisses Maﬁc Volcanics with Calc-silicate lenses Maﬁc Plutonic

Maﬁc Plutonic Thrust fault

Thrust fault Mesoproterozoic Basement Ortogneiss Syn- to late-tectonic granite

Mesoproterozoic Basement Ortogneiss Maﬁc intrusion

Figure 02 - Stra graphic column of Nova Brasilândia vulcanic sedimentary sequence.

Syn- to late-tectonic granite

Maﬁc intrusion

Figure 03 - Stra graphic column of Nova Brasilândia vulcanic sedimentary sequence post deforma on.

Migran nópolis Fm.

Sandstones

Maﬁc volcanics

Crystalline basement Arkose, sandstones and siltstones

Maﬁc plutonics Conglomerates and turbidites

Shale and siltstones

Limestone and calcareous shale

Zn, Pb, Cu mineraliza on Rio Branco Fm.

Figure 04 - The ﬁgure presents an a empt to reconstruct the paleogeography of Nova Brasilândia vulcanosedimentary sequence, taking as an example the model of mineraliza on of the type SEDEX from Emsbo (2009)

A Figure B

P i m e n t a

B u e n o

40km

G r a b e n

Rio Branco Fm.

C o l o r a d o

G r a b e n

-64°

-8°

-60°

BRAZIL

Au ar sanal mine

RONDÔNIA

Cu ar sanal mine

-12°

Cu occurrence

Nova Brasilândia Group

Zn-Pb-Cu occurrence

Project area

BOLIVIA

20km

Figure 02 - Aeromagne c image over Nova Brasilândia Project. Total magne c intensity 1st ver cal derivate with total gradient amplitude superimposed on A and B. A. Regional aeromagne c image showing major regional magne c lineaments, Nova Brasilândia Group loca on and metallic mineral occurrences. B. Aeromagne c image over Nova Brasilândia Group showing magne c lineamentes and metallic mineral occurrences.

0.3 to 3 km long. Near to some siliceous breccias, hydrothermal altera on with >25% of gahnite (Zn oxide) was mapped con nuously along a 2.5 km ESE-WNW trend. Most of the sulﬁde rich zones occur aligned to a magne c lineament with more than 50 km long, interpreted as a sinistral transpressional fault (Figure 06). Nova Brasilandia Zn-Pb-Cu sulﬁde deposit has some similari es with high metamorphic grade SEDEX deposits, as Broken Hill, in Australia. The

similari es are the host rocks, geotectonic se ng and the metamorphic condi ons. Further works from CPRM and academy are necessary to be er understand the mineraliza on controls and geological model. Syn- to late tectonic A-type granite intrude the NBG and aﬀect the mineraliza on as it increases the Sn and W grades in the gossans, mainly near the contact with the plutonic bodies.

Figure 06 - 1) Gossan represen ng a massive sulfide vein (4m thick) hosted by paragneiss of Migran nópolis Fm. A sample with quartz, sulfides, gahnite and iron oxides returned 5.9% Zn, 0.74% Pb and 0.17% Cu; 2) Weathered sulfides along the folia on plane and in veins (0.61% Zn, 1.1% Pb and 0.24% Cu).

References: EMSBO, P. 2009. Geological criteria for the assessement of sedimentar exhalative (sedex) Zn-Pb-Ag deposits: U.S. Gelogical Survey Open-File Report 2009-1209, 21 pp. RIZZOTO, G.J.; LIMA, E. F.; CHEMALE JR., F. 1999. Acresção continental no Estoniano do sudeste de Rondônia. In: SBG-Núcleo Norte, Sim.Geol. da Amazônia, 6, Manaus-AM.

Brazil Geological Survey Under the Spotlight