Journal Article

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

Mechita C. Schmidt-Aursch and Wilfried Jokat

in Geophysical Journal International

Volume 160, issue 2, pages 753-760
Published in print February 2005 | ISSN: 0956-540X
Published online February 2005 | e-ISSN: 1365-246X | DOI: https://dx.doi.org/10.1111/j.1365-246X.2005.02515.x
The crustal structure of central East Greenland—II: From the Precambrian shield to the recent mid-oceanic ridges

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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.

Keywords: continental crust; crustal structure; East Greenland; gravity; oceanic lithosphere

Journal Article.  5717 words.  Illustrated.

Subjects: Geophysics

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