The Structure and Evolution of the East Greenland Continental Margin before Spreading on the Kolbeinsey Ridge

Abstract

An analysis of deep structure for the East Greenland margin (Blosseville Kyst – Liverpool Land) and the Jan Mayen microcontinent yielded a common crustal model for the time before their dispersal. The joint model presents a visual picture of the net result from the Paleozoic, Mesozoic, and Cenozoic rifting phases. Beginning from the Devonian, a graben-like depression approximately 180 km wide has existed between Liverpool Land and the Jan Mayen Ridge. The depression resulted from downwarping of the crystalline basement that was not compensated by sedimentation. The sea basin was approximately 2 km deep at the end of the Devonian. The joint deep crustal section (from west to east) clearly shows three depths to the top of the upper mantle that can be fitted by dome-like surfaces superposed on one another. We interpret these surfaces as temperature fronts resulting from the formation of mantle plumes that took place during different epochs (Paleozoic, Mesozoic–Cenozoic, and Late Cenozoic). A basement high was identified beneath the edge of the present-day Blosseville Kyst and Liverpool Land shelf; the high correlates with the axis of a positive free-air gravity anomaly. East of the high, a continent–ocean boundary is tentatively identified along the axis of the anomaly. The present-day phase in the geological evolution of the Greenland–Norwegian region north of Iceland is characterized by a higher thermal state of the lithosphere and by intraplate tectonic occurrences.