the Expedition ARKTIS-XIX/4 of the research vessel POLARSTERN ...

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In the latest stages of the project, all the results from East Greenland and Norway will
be merged for an integrated interpretation of the entire rift system.
The cruise ARKXIX/4 is the main effort to complete the second part of this project.
Although MCS and potential field data exist on most of the Greenland margin, the
data density seems insufficient to well comprehend the important lateral variations in
structure that can be expected, judging from mid-Nowegian margin studies, where
the data density is much higher. Also, refraction lines imaging the lower crust exist
only along 5 fjords, south of 76°, with limited extension on the outer margin. Still
these relatively scarce data provided important results (e.g. AWI publication Nr
270/1998), including the discovery of a 6km thick underplated magmatic body above
the Moho, which extension remains to be precised. These results show the interest
there is in pursuing further geophysical investigations along the East-Greenland
margin.
By carrying out combined MCS, refraction and magnetic surveys from 73°N to 77°N,
this cruise will greatly contribute to improve our knowledge on this region. The new
data should help to address crustal and uppermost mantle architecture (crustal
thickness variations, rift asymetry, distribution of extrusives, intrusives, magmatic
underplating); interplays of sedimentation, tectonic and magmatic activity (prior to,
during and subsequent to breakup); along-strike segmentation; and structural
inheritance. It will also provide a needed regional framework for the small-scale 3D
geophysical survey, which should be carried out in the future.
Experimental set-up
Refraction data were collected from the shore to the oceanic crust along four lines
(1476 km)(Tab. 2-2, 2-3). Seismic energy was generated with an array of 5x9L
airguns and a 32L airgun and was collected by three components ocean bottom
seismometers (OBS), ocean bottom hydrophones (OBH) provided by GEOMAR, and
4 more from AWI. Along in the 3 profiles. 4 to 8 Reftek stations were also deployed
on shore by helicopter flights for 3 of the profiles.
- Line 2003200; 15 OBS, 10 OBH; Deployment took 21h; shooting 37h; recovery