Crustal structure modelling and interpretation of the East Greenland continental margin between 72°N and 77°N

Abstract

Integrated studies of conjugate margins provide important constraints for the sequence of events of synrift tectonic and magmatic processes. The northeast Greenland margin is investigated based on seismic refraction data acquired across the continent ocean transition zone between the Jan Mayen and Greenland fracture zones. Transects of seismic velocity models reveal a clear segmentation of the margin, which is compatible with the potential field data. A crucially important observation is a thick high velocity lower crustal body which clearly decreases northwards. Excessive magmatism is inferred to have occurred during long-term rifting in the south, while reduced syn-rift intrusions account for the norhtern magma-starved margin. Asymmetries and variations across the adjacent and conjugate East Greenland and Norwegian margins, are controversially discussed in terms of the origin of the lower crustal body and magnetic spreading anomalies. Three hypothetical scenarios for the timing and formation of the high velocity lower crustal body are presented. A comprehensive subsidence analysis is established which quantifies the amount of magmatic underplating.