The syn-rift tectono-stratigraphic record of rifted margins (Part II): A new model to break through the proximal/distal interpretation frontier
Résumé
One fundamental lesson from the last decades research into rifted margins is that stratigraphic horizons cannot be simply correlated from the proximal into distal domain, which makes the interpretation of poorly calibrated and largely inaccessible distal margins difficult. In this contribution, we propose a new tectono-stratigraphic model to help break through the proximal/distal interpretation frontier. After reviewing the scientific advances on rifted margins achieved during the last century, we describe the primary spatio-temporal evolution of active deformation during rifting. We show that different rift domains are associated with specific (1) periods of active deformation; (2) tectonic structures and related stratigraphic architecture; (3) amounts of accommodation creation owing to specific ranges of horizontal widening and vertical deepening; and (4) depositional environments. We demonstrate that the sequential localization of extension during rifting results in a younging of the base of passive infill (i.e., sediment deposited in a non-tectonic setting) oceanward. We propose a panel of few to few tens of My time intervals related to specific tectonic events – our Tectonic Sequences – that may be correlated more or less easily and continuously across rifted margins. This study underlines the value of an iterative approach between fieldwork on fossil rifted margins and offshore geophysical studies, where field studies offer easy-to-access and high-resolution calibration of dismembered rifted margin remnants, while geophysical studies provide comparatively low-resolution imaging of entire, intact but largely inaccessible, rifted margins. It also highlights the necessity of jettisoning outdated dogma on rifted margins and changing our routines when interpreting seismic sections and outcrops.
Origine : Fichiers produits par l'(les) auteur(s)