Sensitivity of Clinoform Geometry to Geological Processes Operating on the Continental Shelf and Slope

Kertznus, Vanessa¹, Ben Kneller¹, Mason Dykstra² (1) University of Aberdeen, Aberdeen, United Kingdom (2) University of California, Santa Barbara, CA

Conventional 3D seismic reflection data acquired by BG on the Ebro continental margin (northwestern Mediterranean), together with wire-line log data from previously drilled wells, allow us to present a morphological analysis of the Plio-Pleistocene shelf-to-slope depositional system of the Ebro, by examining the geomorphic response of clinoform slopes to changing sedimentary and geological conditions.

The seismic data displays a complex pattern of highly prograding and aggrading clinoforms with variable geometry. Two major periods characterize the evolution of this post-Messinian margin in terms of clinoform geometry and slope morphology. Following the Messinian salinity crisis, the first period is characterized by dominantly oblique clinoforms developed as the new Pliocene margin prograded. Rapid progradation resulted in the filling of the underlying Messinian topographic lows. During this period the continental slope is highly incised by closely spaced submarine canyons. The second period is characterized by highly progradational and aggradational, dominantly sigmoidal, and progressively steeper clinoforms, and by an increase in the shelf-to-basin relief. The degree of incision of the continental slope decreases, however submarine canyons are wider and incise deeper.

Mapping of the stratigraphy and quantification of the slope curvature throughout the succession, reveal both along-strike and vertical variations in the morphology and curvature of the continental-margin clinoforms, as the depocenters migrated towards the southwest. Documentation of these morphologies is essential for understanding mechanisms of progradation and sediment distribution, and the interplay between proximity to the sediment source, rate of sediment supply, shelf-to-basin relief, character of oceanographic regime, and sea-level change.