Eustatic Controls on Clastic Deposition I—Conceptual Framework
Published:January 01, 1988
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H. W. Posamentier, M. T. Jervey, P. R. Vail, 1988. "Eustatic Controls on Clastic Deposition I—Conceptual Framework", Sea-Level Changes: An Integrated Approach, Cheryl K. Wilgus, Bruce S. Hastings, Henry Posamentier, John Van Wagoner, Charles A. Ross, Christopher G. St. C. Kendall
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A conceptual framework for understanding the effects of eustatic control on depositional stratal patterns is presented.
Eustatic changes result in a succession of systems tracts that combine to form sequences deposited between eustatic-fall inflection points. Two types of sequences have been recognized: (1) a type 1 sequence, which is bounded at the base by a type 1 unconformity and at the top by either a type 1 or type 2 unconformity and has lowstand deposits at its base, and (2) a type 2 sequence, which is bounded at the base by a type 2 unconformity and at the top by either a type 1 or type 2 unconformity and has no lowstand deposits. Each sequence is composed of three systems tracts; the type 1 sequence is composed of lowstand, transgressive-, and highstand systems tracts, and the type 2 sequence is composed of shelf-margin, transgressive-, and highstand systems tracts. The type 1 sequence is associated with stream rejuvenation and incision at its base, whereas the type 2 sequence is not.
Eustacy and subsidence combine to make the space available for sediment to fill. The results of this changing accommodation are the onlapping and offlapping depositional stratal patterns observed on basin margins. Locally, conditions of subsidence and/or uplift and sediment supply may overprint but usually will not mask the effects of global sea level. Any eustatic variation, however, (e.g., irregular eustatic rise or fall, asymmetric fall, slow or rapid rise or fall, and so on) will be globally effective. The significance of eustatic fall-and-rise inflection points is considered with regard to the occurrence of unconformities and condensed sections, respectively. Type 1 unconformities are related to rapid eustatic falls, and type 2 unconformities are related to slow eustatic falls.
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Sea-Level Changes: An Integrated Approach
Sea-Level Changes: An Integrated Approach - In October 1985, SEPM sponsored a four-day conference entitled ?Sea-Level Changes ? An Integrated Approach.? The purpose of the conference was to provide a forum for an interdisciplinary exchange of ideas on sea-level changes and to provide an opportunity for integrating various types of evidence in approaching unresolved issues. The conference was successful in bringing together scientists from industry, academia, and government, representing all of the major geosciences disciplines. Presentations of many new papers, plus significant releases of data that were previously held proprietary, provided fertile ground for discussion. This much-cited volume represents the best of the material presented at the conference. Includes the early ?Vail? chart.