Post-Rift Tectonics in Rifted Margins and Surrounding Domains

Abstract

When examining the tectonic evolution of rifted margins, the focus is usually on the syn-rift period where the tectonic processes are active, driving lithospheric deformation and leading to continental breakup. While, the post-rift period is often assumed to be tectonically passive and controlled by the cooling of the thermally perturbed thinned lithosphere. However, many rifted margins around the world (e.g. West Greenland, Norway, NW Africa, NE Brazil, NW Australia) show major sedimentary unconformities overlain by a relatively thick siliciclastic succession in the offshore, 20 to 60 Ma after breakup. Onshore, contemporaneous km-scale vertical movements and shortening events affecting the continental domain are recorded and can be found hundreds of kilometers away from the coastline. In the Central Atlantic, where continental breakup occurred in the Early Jurassic, a thick Lower Cretaceous siliciclastic sequence is found offshore NW Africa, sitting on a major Late Jurassic unconformity. In addition, up to 3 km of crustal exhumation affected several onshore domains between the Late Jurassic and the Late Cretaceous. In this work, we examine the post-rift evolution of the East Central Atlantic margin and we investigate the processes that might have driven the observed exhumation and denudation of the surrounding onshore domains.

AAPG Datapages/Search and Discovery Article #90291 ©2017 AAPG Annual Convention and Exhibition, Houston, Texas, April 2-5, 2017