STRUCTURE OF THE NORTH EAST GREENLAND MARGIN CONSTRAINED BY POTENTIAL FIELD DATA

The North East (NE) Greenland shelf extends from 68ºN to 83ºN. Its structural elements as well as the evolution of the entire NE Greenland margin are, due to the lack of geophysical data, still poorly understood. Particularly, the area north of the Jan-Mayen Fracture Zone (JMFZ) located at about 71ºN shows strong variations in its crustal configuration. Transects across the margin revealed vertical and lateral variations in lower crustal composition: a large lower crustal high velocity body (HVB) was detected by deep seismic sounding. Most interestingly, the HVB disappears within only a few hundred kilometers northwards. That body, interpreted as magmatic layer, results from the complex history of rifting that led to break-up between Greenland and Scandinavia. The basins north of JMFZ up to Fram Strait were formed in a slow respectively ultra-slow spreading environment prior to and during late Cretaceous - early Tertiary times. While the southern part of the margin (the area of Scoresby Sund and Kong-Oscar-Fjord) shows clear evidence for a massive volcanism, this is not the case for the margin north of the Greenland Fracture Zone (GFZ).The crustal structure and development of the northernmost shelf region is as well almost unknown due to the lack of seismic refraction data. Interesting is the occurrence of salt diapirs in the northern part of the Danmarkshavn Basin (DB) that are hardly mapped so far. Single structures were detected in seismic reflection surveys in the northernmost area on the shelf, but for a complete mapping the seismic network is not dense enough.To better determine the margin's crustal structure, commercial aero-gravity data (courtesy of TGS NOPEC, Olso), gathered during surveys in 2007/2008, was modeled in 3D including crustal information from published deep seismic sounding data. The existing 3D gravity model (Schmidt-Aursch and Jokat, 2004) for the shelf, which gives insight into the margin's features up to 75ºN, was extended to about 81ºN. Furthermore, the southernmost part of the 3D gravity model between Scoresby Sund and Shannon Island was refined to take the new deep seismic sounding results concerning the continent-ocean transition's (COT) structure (Voss and Jokat, 2007) into account.The interpretation focuses on general crustal structures, which vary in N-S direction of the shelf and might result of different rifting processes.The results of the 3D modeling in conjunction with the deep seismic models will be shown and discussed. Where necessary aero-magnetic data of the same area will be used to constrain the interpretation. Schmidt-Aursch, M., Jokat, W., 2004. The crustal structure of central East Greenland - II: From the Precambrian shield to the recent mid-ocean ridges, Geophysical Journal International Voss, M., Jokat, W., 2007. Continent-ocean transition and voluminous magmatic underplating derived from P-wave velocity modelling of the East Greenland continental margin, Geophysical Journal International