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Shelfbreak Physiography: An Overview

By
Jean-René Vanney
Jean-René Vanney
Département de Géologie Dynamique, Pierre et Marie Curie University, and Institut de Géographie,
Sorbonne, Paris, France 75005
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Daniel Jean Stanley
Daniel Jean Stanley
Division of Sedimentology, Smithsonian Institution,
Washington, D.C. 20560
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Published:
January 01, 1983

ABSTRACT

The shelfbreak (SB) is a distinct, critical interface of continental margins which delineates the major physiographic boundary between two major submarine provinces, shelf and slope. The shelfbreak is defined as that point of the first major change in gradient at the outermost edge of the continental shelf, and its depth, distance from shore and configuration are highly variable. Although structural framework is a dominant controlling factor, depositional regime and consequent progradational and regradational development generally modifies, substantially, the shelf-to-slope configuration. These depositional considerations include, among others, sediment supplied by rivers, carbonate reef buildup, influence of ice transport at high latitudes, and the interplay of fluid-driven and gravitative processes active in environments at and adjacent to the break. Moreover, the imprint (relict) of earlier eustatic oscillations, particularly low stands when the SB was at or close to the coastline, is still in evidence.

This overview, which incorporates observations in diverse geological and geographic settings, focuses on geomorphological aspects and is an attempt to synthesize shelfbreak type by means of a descriptive-genetic classification which takes into consideration the interaction of the dominant controlling factors. These are: (a) structural framework and rate of substrate motion which are functions of the larger-scale geological evolution of a margin, (b) the overprint of earlier (largely Quaternary) climatic and eustatic events, and (c) sediment supply and processes (reviewed in terms of climatic belts). The interplay of these three large-scale parameters has, of course, varied considerably in time and space, giving rise to a diverse suite of “end-member” break and transitional variants. In summary, we view the shelfbreak as a reworked palimpsest feature which has not yet attained complete equilibrium with presently active processes.

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SEPM Special Publication

The Shelfbreak: Critical Interface on Continental Margins

Daniel Jean Stanley
Daniel Jean Stanley
Division of Sedimentology Smithsonian Institution
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George T. Moore
George T. Moore
Chevron Oil Field Research Company La Habra California
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SEPM Society for Sedimentary Geology
Volume
33
ISBN electronic:
9781565761636
Publication date:
January 01, 1983

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