Morphotectonic features characterize flexural uplift during early intracontinental rifting

Institute of Applied Geoscience seminar. Speaker David Fernández-Blanco, Institut de Physique du Globe de Paris

Abstract

Elastic flexure of the lithosphere is commonly used to model crustal mechanics, rheology and dynamics. However, accurate characterizations of flexure in nature at the spatiotemporal scale of active intracontinental rifting (tens of km; 104-106 yr) are scant. I show in this talk how we use morphotectonic features to characterize flexural uplift during early intracontinental rifting in the fastest extending intracontinental rift on Earth that is accessible subaerially, the Corinth Rift in central Greece. Exceptionally preserved geomorphological elements throughout the uplifting margin of the rift show the combined effect of progressive uplift and footwall flexure. Across the rift margin, marine terraces, footwall longitudinal river profiles and topography define uplift increasing exponentially towards the bounding fault. Along the rift margin, geomorphic proxies for fault’s cumulative displacement, footwall relief, slip rate and uplift rate show parabolic distributions decaying along strike away from the fault center. Conspicuous drainage reversals where the topographic expression of elastic flexure is most prominent similarly suggest that maximum slip rates occur at the rift center. Overall, the geomorphic evidence for flexure implies young, disruptive onset of a highly-localized, master fault system of crustal scale controlling the growth of the modern Corinth Rift. Similar highly-localized strain and associated elastic flexure of the lithosphere may have occurred elsewhere, including old and/or slow-extending rifts and areas of intracontinental extension lacking adequate geomorphic evidence.