Recognition and Interpretation of Depositional Sequences and Calculation of Sea-Level Changes from Stratigraphic Data—Offshore New Jersey and Alabama Tertiary
Published:January 01, 1988
Stephen M. Greenlee, Theodore C. Moore, 1988. "Recognition and Interpretation of Depositional Sequences and Calculation of Sea-Level Changes from Stratigraphic Data—Offshore New Jersey and Alabama Tertiary", 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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Tertiary depositional sequences beneath the continental shelf and slope off New Jersey and Alabama have been studied using seismic-reflection data that have been tied to available wells. These data illustrate second- (10–20 Ma) and third-order (1–5 Ma) depositional sequences in areas close to and distal to progradational siliciclastic depocenters. Paleogene deposition is characterized by sediment-starved deep-water conditions. Second-order sequence boundaries divide these sediments and are recognized by local erosion of underlying strata and deep-marine onlap. Closer to the depocenter, third-order sequences are noted by basinward shifts in coastal onlap, local erosional incision of shelf and slope strata, and planar erosion of basinal sediments. The stacking pattern of third-order sequences within the second-order sequences is similar to the stacking of systems tracts within the third-order depositional sequences modeled using a sinusoidally varying sea-level curve. Upper Oligocene to uppermost middle Miocene third-order sequences are interpreted to compose a second-order super sequence.
Neogene strata in these areas are further analyzed to estimate sea levels. Subsidence is isolated using geohistory analysis and by calculating the average angular-tilt rate of the continental margin. During the early Tertiary, the subsidence rate was slow in both areas. An increase in subsidence rate in the offshore Alabama area during the Neogene is attributed to loading of the lithosphere adjacent to the study area. Short-term falls in sea level are estimated by measuring the vertical shift in onlapping paralic strata from highstand to lowstand position. Results show a lower overall Neogene sea-level position than the position represented on the Exxon curve but similar magnitudes of short-term fall.
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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.