Gravity-driven Tear Faults - a Control on Sediment Routing in Deepwater Settings

Abstract

We use 3D seismic data from offshore of Mauritania and offshore Nigeria to assess the interactions between tear faults and deepwater channel systems on continental margins. Structural observations combined with channel analysis are performed in four case studies in order to illustrate a variety of settings and stages of development. Based upon our data we propose that new gravity-driven tear faults are the sites for the early stages of canyon and channel development, leading to a long-lived canyon. Low sinuosity and a deep incision thalweg are characteristics of these stages. We also describe the submarine channels migration history around strike-slip structures parallel to the continental slope. Channel analysis provides an illustration to the evolution of channel systems and focus points in pull-apart basins. Observed spatial relationships suggest that: (1) tear fault zones can strongly confine submarine channel development; (2) this control persists over successive stages in the evolution of the fault and channel systems; (3) we propose that a complex interplay exists between fault deformational processes and channel systems development. These interrelationships occur at a variety of scales, and since gravitational faults and deepwater channel and canyons occur in similar settings our synoptic model should have application elsewhere.