FOCUS NGU FOCUS NR.7, AUG 2016
PL E A
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W W W E VISIT .NG FOR M U.NO I N FO R O R E MATI ON
HELICOPTER BORNE GEOPHYSICS NGU FOCUS 24.08.2016 / WRITTEN BY JAN STEINAR RØNNING
The Geological survey of Norway (NGU) has carried out airborne geophysical surveys since 1958. After covering mainland Norway and parts of the continental shelf with fixed wing magnetic measurements, a program for high resolution helicopter-borne geophysics was started in the early seventies. The present instrument package includes magnetic, electro-magnetic and radiometric measurements. In normal situations the radiometric sensor is mounted underneath the helicopter, while the magnetic sensor is placed inside the EM bird suspended 30 metres beneath the helicopter. Nominal flying height is 60 metres above the ground and the speed is usually 100 km/h (approx. 30 m/sec.). Instrumentation and survey design are adjusted to suit client requirements.
NGU is the central national institute for knowledge of the bedrock mineral resources, superficial deposits and groundwater of mainland Norway. Outside the oil industry, NGU is the largest environment for geology and geophysics in Norway.
During the last 40 years NGU has carried out high resolution helicopterborne surveys for mineral exploration, bedrock mapping and environmental studies both in Norway and in neighbouring countries. From 2011 to 2015, intensive helicopter-borne geophysics was performed as a part of the MINN (MIneral resources in Northern Norway) and MINS (MIneral resources in Sorthern Norway) projects. Radiometric ternary map, Lofoten – Vesterålen – Troms area, Northern Norway.
Present NGU helicopterborne geophysics.
NGU, GEOPHYSICAL EQUIPMENT USED FROM HELICOPTER. Magnetic: Scintrex Cesium-magnetometer. - Cs-2 sensor, Sensitivity 0.001 nT. - GEM GSM-19 base-station. Electromagnetic: Geotech Hummingbird, 5 frequencies. Coil separation ca 6.0 metres, noise level 1–2 ppm. - Coplanar 880 Hz - Coplanar 6606 Hz - Coplanar 34133 Hz - Coaxial 980 Hz - Coaxial 7001 Hz
Navigation: GPS fixed to helicopter - Accuracy: (+/- 5 m) Altimeter: Radar altimeter permanent in helicopter. - Accuracy: 5% of measured height. Datalogger:
In house PC-based acquisition
Processing software:
Geosoft OASIS Montaj
The NGU has an approval from EASA (European Aviation Security Agency) to use this equipment in a helicopter.
Radiometric: Radiation Solutions RSX-5. - Crystal volume, 16 litres down ward looking - 4 litres upward looking - Spectrometer, 1024 channels
FOR FURTHER INFORMATION, PLEASE CONTACT:
JAN STEINAR RØNNING Team leader jan.ronning@ngu.no +47 90861125 / +47 73904441
NGU - GEOLOGICAL SURVEY OF NORWAY CONTACT ADDRESS
VISITING ADDRESS
SOCIAL MEDIA
PO Box 6315 Sluppen NO-7491 Trondheim, Norway Phone: +47 73 90 40 00
Leiv Eirikssons vei 39, Trondheim E-mail: ngu@ngu.no www.ngu.no
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