The structure and evolution of the east Greenland continental margin before spreading started on the Kolbeinsey ridge

Abstract

An analysis of the deep structure of the East Greenland margin (Blosseville Kyst to Liverpool Land) and of the Jan Mayen microcontinent resulted in the development of a crustal model that was valid for both before their disruption. A joint model clearly demonstrates the net result of rifting phases during Paleozoic, Mesozoic, and Cenozoic time. Starting from the Devonian, a graben-shaped depression about 180 km wide existed between Liverpool Land and the Jan Mayen Ridge; the depression was formed by subsiding of the crystalline basement that was not compensated by sedimentation. The marine basin was approximately 2 km deep during late Devonian time. The west-east joint deep crustal section clearly defines three depths in the upper mantle that fit dome-like surfaces superposed on each other. We interpret these surfaces as temperature fronts of mantle plumes that differ by their time of origin: Paleozoic, Mesozoic to Cenozoic, and late Cenozoic. The rim of the present-day Blosseville Kyst and Liverpool Land shelf is found to be underlain by a basement high that is associated with the axis of a positive free-air gravity anomaly. East of the high along the anomaly axis, we identified a continent-ocean boundary. The present-day phase in the geological evolution of the Greenland-Norwegian region north of Iceland is characterized by an increased thermal state of the lithosphere and manifestations of intraplate tectonics.