The crustal structure of central East Greenland - II: From the Precambrian shield to the recent mid-oceanic ridges

• Published in: Geophysical Journal International
• Main Authors: Schmidt-Aursch, Mechita C., Jokat, Wilfried
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2005
• Subjects: Greenland; Kolbeinsey; Kolbeinsey Ridge; East Greenland
• Online Access: https://epic.awi.de/id/eprint/10468/; https://doi.org/10.1111/j.1365-246X.2005.02515.x; https://hdl.handle.net/10013/epic.20945

We present a 3-D crustal model of the East Greenland Fjord Region between 69°N and 74°N. The model covers the Precambrian shield and the Caledonian orogenic belt, the adjoining Devonian and Mesozoic basins, the continent-ocean transition and the Cenozoic oceanic areas as far as the Kolbeinsey and the Mohns mid-oceanic ridges. Existing seismic models of the crustal structure are extrapolated into adjacent areas using 3-D gravity modelling. For this purpose, we compile a new regional-scale Bouguer anomaly map. The Precambrian shield, west of the Caledonian orogen (approximately west of 32°W), shows a mean thickness of 35 km with only small-scale undulations. This thickness is at the lower limit of the global range in shield thickness. The Caledonian orogen exhibits a pronounced mountain root with overall crustal thicknesses up to 51 km. Beside the Urals, the East Greenland Caledonides are one of the two Palaeozoic mountain belts where a crustal root has preserved to the present day. Continuation of the crustal model to the east, beyond the continent-ocean transition, yielded thicknesses of the crystalline oceanic crust from 9 km near the Kolbeinsey Ridge to 3 km west of the Mohns Ridge. Differences in the thermal structures of the old continental and the young oceanic lithosphere are responsible for the low-density mantle beneath the oceanic crust, which is also demonstrated by 3-D gravity modelling.