AEM Greenland 1997
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Description of an airborne combined electromagnetic and magnetic survey in Greenland 1997
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The survey area covers the northern portion of the Jameson Land basin which is a thick sequence (up to 17 km) of Palaeozoic and Mesozoic continental and marine sediments invaded by a variety of Tertiary sills, dykes and intrusions.
The region has a history of both hydrocarbon and mineral exploration, the latter being the focus of this study. The Blyklippen lead-zinc deposit was commercially mined between 1956-1962 by Nordisk Mineselskab A/S and, although small, is one of the few operating mines in Greenland's history. It is situated within the survey area in the Mesters Vig region.
Many other mineral occurrences are known. The Malmbjerg porphyry molybdenum deposit is probably the best known prospect in the area is associated with a Tertiary intrusion and is situated west of the geophysical survey block.
Two long reconnaissance lines were flown north of the main survey area to gather some geophysical information for future planning.
In 1998 selected anomalies were visited in a follow-up study by GEUS, which concluded that most electromagnetic anomalies are found in relation to thick Tertiary sills intruded into black Jurassic shales and are probaly caused by a combination of contact-metamorphosed, graphite-bearing black shales and massive to semi-massive contact-skarn sulphide/magnetite layers found in these sediments.
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The total magnetic field anomaly of the Ørsted Dal ironskarn deposit discovered in connection with a ground follow-up on selected anomalies from AEM Greenland 1997.
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The geophysical survey aircraft in the air over Constable Pynt, central East Greenland. Flight alitude is 120 m over terrain with the magnetic and electro-magnetic sensor 75 m and 70 m above ground, respectively.
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Survey area
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Northern Jameson Land (including eastern Scoresby Land), central East Greenland.
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Period
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Survey flown from July 7th to 24th August, 1997.
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Survey specifications
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The survey includes electromagnetic (GEOTEM) and magnetic total field measurements.
Survey lines were oriented east-west at 400 metres interval with north-south directed tie-lines spaced at four kilometres interval.
Nominal flight altitude is 120 metres over terrain with the total field magnetic sensor and electromagnetic sensor 75 metres and 70 metres above ground, respectively.
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Areal extent
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5194 km2 |
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Acquisition and processing
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Geoterrrex-Dighem Ltd.
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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 at 1:50 000 scale
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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 with IGRF removed
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Calculated magnetic vertical gradient contours
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Conductance contours calculated from the GEOTEM Z-coil data
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GEOTEM X-coil channel 12 amplitude contours
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Digital terrain model (DTM) using radar altimeter and GPS elevations
A total of 13 geophysical map sheets, in scale 1:20 000, are provided for the parameter listed. A single map sheet of 1:250 000 scale was produced for the entire survey area for each of the listed parameters. One flight path map in scale 1:500 000, including reconnaissance lines was also produced.
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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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Survey financed by
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Government of Greenland.
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Selected references
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Geoterrex-Dighem Ltd. 1997;
Stemp, R.W. 1998;
Pedersen & Stendal, 1999;
Nielsen, 2000.
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Further information
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Contact GEUS, Department of Petrology and Economic Geology, at
petromalm@geus.dk.
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