AEM Greenland 1996
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Description of an airborne combined electromagnetic, magnetic and radiometric survey in Greenland 1996
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The survey area is located in the Grønnedal region, South-West Greenland. Five separate blocks were surveyed, primarily covering the Ketilidian (early Proterozoic) and Tartoq (Archean) supracrustal belts.
The Archean is dominated by 2.7 to 2.9 Ga old gneisses, but contains the older Tartoq Group supracrustals consisting of mafic to ultramafic metavolcanic units with subordinate felsic metavolcanic or metasedimentary rocks intruded by a granitoid dated at c. 2.944 Ga. The Archean basement is unconformably overlain by Ketilidian supracrustal rocks and is intruded by Ketilidian dolerite dykes and granites. The supracrustal rocks are almost unmetamorphosed at Midternæs, while the metamorphic grade increases to amphibolite facies in southern Grænseland and Arsuk Ø.
The survey blocks are situated near the southern Archean boundary of West Greenland and were initially selected to cover both Proterozoic and Archean supracrustal belts with a potential for economic base metal or precious metal mineralisation.
The multi-frequency EM survey mapped a large number of bedrock conductors, particularly within the Ketilidian rocks of Midternæs and Grænseland.
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Grønlandsfly A/S helicopter during take-off from Grønnedal in South-West Greenland with its geophysical intrumentation from Aerodat Inc.
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Survey area
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Grønnedal region, South-West Greenland.
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Period
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Survey flown from 30th May to 22th October, 1996.
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Survey specifications
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Multi-sensor, helicopter geophysical survey system including multi-frequency HEM system, magnetometer and VLF-EM sensors placed in two birds below the helicopter. All other equipment is mounted on the helicopter platform, including a gamma ray spectrometer, a video camera, the GPS navigation system, radar and barometric altimeters.
The multi-frequency HEM system is housed in the lower bird at a mean survey terrain clear-ance of 30 metres. The upper bird is flown at 45 metres terrain clearance and houses both the magnetometer and VLF-EM sensors.
The survey was flown at a mean helicopter terrain clearance of 60 metres with survey lines spaced at 200 metres and orthogonal tie-lines at 2000 metres.
A total of 8756 linekilometres of geophysical data were acquired over five separate survey blocks, namely:
Survey Block (line direction; line km)
1) Sermiligaarsuk North (150o; 3540 km)
2) Midternæs (150o; 2950 km)
3) Grænseland (90o; 1515 km)
4) Sioralik South (90o; 463 km)
5) Arsuk Ø (0o; 288 km)
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Areal extent
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1560 km2 |
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Acquisition and processing
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Aerodat Inc.
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Data and maps
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Digital line and grid archives on CD-ROM
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Multi-channel stacked profiles - one plot per flight line showing all measured / calculated parameters
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Maps of the following parameters:
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Base maps with flight lines and EM anomalies
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Total magnetic intensity contours
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Calculated magnetic vertical gradient contours
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EM profile maps (in-phase and quadrature) for the 4600 Hz horizontal coaxial loop
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Calculated apparent resistivity contours based on the 4200 Hz vertical coplanar loop
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VLF-EM total field contours
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Total count radiometric contours
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Potassium count contours
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Uranium count contours
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Thorium count contours
A total, for the five survey blocks, of 17 geophysical map sheets in scale 1:20 000 were produced for the parameter listed. One map, in scale 1:100 000, covering all five survey blocks, was produced for each of listed.
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Examples of maps
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Products available from GEUS
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Digital data with survey report and maps - see
How to order products.
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Financed by
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Government of Greenland.
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Selected references
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Aerodat Inc. 1997;
Stemp, R.W. 1997.
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Further information
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Contact GEUS, Department of Petrology Economic Geology, at
petromalm@geus.dk.
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