9.5.2. Remanence acquisition.
There continues to be uncertainty as to the mode of acquisition of speleothem remanence. This arises from the inability to differentiate between CRM and DRM components that contribute to the NRM. The relationship between weight % acid insoluble detritus and NRM intensity is discussed in section 8.6 . This method requires further systematic work but may have the potential to distinguish between a DRM or a CRM remanence.
All speleothems in this study have been taken from Hood-prone streamways. In both Matienzo and Xingwen, large scale flooding occurs on a yearly basis. The results of these Hoods are seen within each speleothem as finely laminated, alternating light and dark growth layers. These dark layers represent growth immediately after a Hood which cements detritus into the calcite matrix. The light layers represent growth after flood detritus has been cemented in to the calcite matrix prior to the next flood. Therefore the primary source for magnetic minerals within the calcite matrix is likely
be firm, direct
deposition of magnetic minerals onto the speleothem surface from flood events- a DRM Unforiunately, no material was taken from the cave floors in either Matienzo or Xingwen. It has, therefore, not been possible to rnmnc.™ ^ pu^ioie to compare the magnetic properties of the cave floor sediments to the detritus within the speleothems
A second possible source for detrital mntnrioi • , or aetntal material within the speleothems was from the drip-waters. Bull (1981) suggested that fissure« «/¡m;„,u , • limestone, which assures within the overlying cany the drip-waiers, can cany grains of up to 45pm. However, over the long periods required for speleothem growth it is likely tha, these fissures become blocked and will subsequently filter-out MD grains (Latham and Ford 199ft tn tn f ,. • ■ w u, w v ih In the. future, examination of the magnetic properties of surface «nils i e solls above known speleothems and their drip waters may go some way to illustrate which maorwi« „ • . mcn magnetic grain types and sizes are carried by this mechanism. Latham (1981) found that th^ • uuu mat the overlying soils were the source for iron oxyhydroxides within speleothems in some caves
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