Review of Greenland Avtivities 2001 - Aeromagnetic survey ... - Geus

56° 54° 52°
72°
72°
71°30′
71°
70°30′
50 km
71°30′
71°
nT
608
364
233
150
78
35
6
– 13
– 29
– 43
– 55
– 66
– 75
– 84
– 92
– 100
– 108
– 117
– 124
– 131
– 138
– 145
– 151
– 159
– 166
– 175
– 184
– 194
– 206
– 222
– 242
– 271
– 325
– 387
– 460
– 546
– 653
– 815
56° 54° 52°
Fig. 2. Magnetic total field intensity with shaded relief for the area in central West Greenland covered by project Aeromag 2001.
The location of the aeromagnetic survey in 2001 is circumscribed by a grey line and the new data have been merged with data from
project Aeromag 1997.
field intensity and flight path) each comprising 32 sheets
at scale 1:50 000 are included in the map series.
The gridded magnetic total field data from Aeromag
2001 are shown in Fig. 2. The data have been merged
with those from the Aeromag 1997 project. The International
Geomagnetic Reference Field corresponding
to the date of measurement has been subtracted from
the data. Shaded relief data, superimposed on the magnetic
total field data, have been modelled by using a lightsource
illumination from north with an inclination of 45°.
The magnetic anomalies are in the range from –2500 to
2000 nT. The calculated vertical gradient of the magnetic
total field is shown in Fig. 3 for the merged data set.
Some implications of the new geophysical data for the
interpretation of the geology are given below after a short
introduction to the geology.
Geology of the surveyed area
Five geological maps at scale 1:100 000 have been published
of the surveyed area by the Survey; a descriptive
text for three of the map sheets is given by
Henderson & Pulvertaft (1987). The surveyed area
between Uummannaq and Upernavik Kujalleq/Søndre
Upernavik comprises Archaean crystalline basement
rocks overlain by a several kilometres thick succession
of Palaeoproterozoic supracrustal rocks; they are intruded
by a Palaeoproterozoic granitic complex. Minor units
of down-faulted Cretaceous sediments occur, and
Palaeogene plateau basalts are prominent onshore and
offshore. The Precambrian rocks have been correlated
with similar rocks on Baffin Island in Canada, and were
folded and metamorphosed during the Hudsonian
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