ABSTRACT: Passive Margin Synthetic Stratigraphy: Eustatic Control on Deposition and Preservation Potential on the Continental Shelf

Nicholas Pinter

An automated algorithm synthesizes the stratigraphy of a passive margin, humid-temperate, clastic-dominated continental shelf. The algorithm is based upon numerical equations of sediment supply, storage, and deposition. A sine function is used to model symmetrical sea level rise and fall, depositing a succession of transgressive and regressive facies upon the continental shelf. The resulting stratigraphic profile is analyzed for systematic biases in the preservation of material originally deposited. Variables such as the strength of shoreface erosion and the contact between diffuse (Atlantic style) or concentrated (Gulf style) fluvial input have little affect on the biases of stratigraphic representation. However, the time scale of eustatic fluctuation plays a major contr lling role in the character of the resulting stratigraphic package. During very rapid sea level oscillations, deposits dating to the transgressive half of the eustatic curve may be severely reduced or absent entirely. Ongoing sediment starvation on the U.S. Atlantic margin through the last deglacial transgression provides evidence of this process. However, during gradual, tectonic-eustatic sea level change over millions to hundreds of millions of years, preferential erosion of regressive and highstand deposits leads to a systematic underrepresentation of these time periods in the stratigraphic record, and transgressive and lowstand periods are correspondingly overrepresented.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990