Condensed Sections: The Key to Age Determination and Correlation of Continental Margin Sequences
Published:January 01, 1988
Tom S. Loutit, Jan Hardenbol, Peter R. Vail, Gerald R. Baum, 1988. "Condensed Sections: The Key to Age Determination and Correlation of Continental Margin Sequences", 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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Condensed sections play a fundamental role in stratigraphic correlation, both regionally and globally. Condensed sections are thin marine stratigraphic units consisting of pelagic to hemipelagic sediments characterized by very low-sedimentation rates. Areally, they are most extensive at the time of maximum regional transgression of the shoreline. Condensed sections are associated commonly with apparent marine hiatuses and often occur as thin, but continuous, zones of burrowed, slightly lithified beds (omission surfaces) or as marine hardgrounds. In addition, condensed sections may be characterized by abundant and diverse planktonic and benthic mi-crofossil assemblages, authigenic minerals (such as glauconite, phosphorite, and siderite), organic matter, and bentonites and may possess greater concentrations of platinum elements such as iridium.
Condensed sections are important because they tie the temporal stratigraphic framework provided by open-ocean microfossil zonations to the physical stratigraphy provided by depositional sequences in shallower, more landward sections. Condensed sections represent a physical stratigraphic link between shallow- and deep-water sections and are recognized by the analysis of seismic, well-log, and outcrop data. Within each depositional sequence, condensed sections are best recognized and utilized within an area from the shelf/slope break landward to the distal edge of inner neritic-sand deposition. Where sedimentation rates are generally low, as in the deep ocean, a number of condensed sections may coalesce to form a composite condensed section.
Data from detailed analyses of continental-margin condensed sections are presented to illustrate the nature and importance of condensed sections for dating and correlating continental-margin sequences and reconstructing ancient depositional environments.
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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.