A tectonic model for the Norwegian passive margin with implications for the NE Atlantic: Early Cretaceous to break-up

Abstract

A sub-regional tectonic study of the mid-Norwegian margin has been assimilated into a broader, regional study of the NE Atlantic margin. The NE Atlantic margin experienced several extensional events between Devonian post-orogenic collapse and break-up in Early Tertiary. This paper focuses on the extensional events between Early Cretaceous and Early Tertiary. It is suggested that NE-trending Early Cretaceous rifting followed the entire margin from the southern Rockall Trough to the Bjornoya Basin of the SW Barents Sea. This rift had a markedly different trend than the preceding N-trending Late Jurassic rift of, e.g., the North Sea. Seamounts may have been emplaced in the highly thinned basin axes during Early Cretaceous rifting. Subsequent rift events followed the Early Cretaceous rift trend. An enigmatic 9mid9-Cretaceous event, probably extensional, is observed in the northern part of the mid-Norwegian margin. The event is expressed by faulting in the inner Voring Basin, and by uplift of the outer Voring and Lofoten margins. Uplift is associated with a widespread unconformity. Uplift of the Gjallar Ridge in the Voring Basin culminated during the latest Cretaceous to Early Tertiary rifting, with structural geometries broadly similar to those seen in core complexes. A new tectonic model for NE Atlantic margin is proposed based on these observations, and builds on analogues from the modern rift system in the Red Sea and Woodlark Basin of Papua New Guinea.