Depositional framework and genesis of Wilcox Submarine Canyon systems, Northwest Gulf Coast

Conference · Fri Jan 01 04:00:00 EST 1988

OSTI ID:6591279

Galloway, W F; Dinqus, W F; Paige, R E

Wilcox (late Paleocene-early Eocene) slope systems of the Texas coastal plain contain two families of paleosubmarine canyons that exhibit distinctly different characteristics and stratigraphic settings: Yoakum and Lavaca type canyons occur as widely separated features within the generally retrogradational middle Wilcox interval. Four such canyons exhibit high length to width ratios, extend far updip of the contemporaneous shelf edge, were excavated deeply into paralic and coastal-plain deposits, and were filled primarily by mud. Fills consist of a lower onlapping unit and capping progradational deposits that are genetically related to deposition of the upper Wilcox fluvial-deltaic sequence. Significantly, the canyon fills correlate with widespread transgressive marine mudstones (the Yoakum shale-Sabinetown Formation and ''Big Shale''). In contrast, Lavaca-type canyons form a system of erosional features created along the rapidly prograding, unstable lower Wilcox continental margin. Comparative analysis of the two canyon system suggests a general process model for submarine canyon formation on prograding basin margins. Key elements are depositional loading of the continental margin creating instability, initiation of a large-scale slump, family of slumps, or listric bedding-plane fault creating a depression or indentation in the margin, and headward and lateral expansion of the depression by slumping and density-underflow erosion. Extent of canyon evolution varies according to time and submerged space available for maturation; short, broad canyons form on narrow shelves of actively prograding margins, and elongate mature canyons form in retrogradational or transgressive settings.

• OSTI ID: 6591279
• Report Number(s): CONF-880301-
• Country of Publication: United States
• Language: English

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