--> Abstract: Nested Submarine Canyon Complexes in Delta Flank Positions: A Structural Model, by E. A. Duncan; #91012 (1992).

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ABSTRACT: Nested Submarine Canyon Complexes in Delta Flank Positions: A Structural Model

DUNCAN, EDWARD A., BP Exploration Operating Co. Ltd., Uxbridge, England

Submarine canyon complexes within large scale siliciclastic sequences have been recognized as potentially important geomorphic features affecting both shelfal and deep water depositional processes. Several large canyon systems have been recognized in the subsurface as occurring on the flanks of major deltaic headlands and appear to have complex histories of recurrence resulting in "nests" of roughly stacked canyons. Genetic models postulating canyon evolution vary widely from deep fluvial incision of an exposed shelf during major eustatic lowstand events to relatively passive headward erosion by shelf margin slumping during sea level highstand.

Examination of seismic profiles across the modern Avon Canyon offshore northwest Niger delta, a previously unnamed canyon offshore Angola (formally suggest: Quicama Canyon), and review of subsurface studies of several major canyon complexes within the Tertiary Gulf of Mexico Basin suggests a dominantly structural genetic model. Lateral variations in rates of thin-skinned extension along a basin margin possibly coupled to deeper crustal fabric create complex zones of linked displacement transfer and large extensional faults. The fault zone trends roughly perpendicular to depositional strike-oriented thin-skinned extensional faults and underpins the genesis of some large-scale, vertically persistent canyon systems. During periods of sea level highstand, continued gravitationally driven hin-skin deformation creates linked and starved extensional half-grabens and crestal collapse grabens creating the dip-oriented and basinward-opening canyon. Scale of canyonization is tied genetically to continuity of the transfer fault trend and magnitude of displacement achieved during the time of sea level highstand.

 

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)