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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 65 (1981)

Issue: 5. (May)

First Page: 983

Last Page: 983

Title: Model of Transgressive Barrier Island Stratigraphy: ABSTRACT

Author(s): Christopher H. Ruby, Peter J. Reinhart

Article Type: Meeting abstract


Cape Romain, South Carolina, is a large cuspate foreland, 50 km north of Charleston. Geomorphically, it is a barrier-marsh-lagoon complex in a state of rapid transgression. Historically, the shoreline has retreated more than a kilometer; the present retreat rate averages 10 m/year. A detailed coring program was undertaken to determine the Pleistocene-Holocene stratigraphy of the cape. The resulting depositional model has been correlated to the Cretaceous of Wyoming and the Carboniferous of Alabama.

Unconsolidated Pleistocene and Holocene sediments lie unconformably over Oligocene marls. These late Pleistocene facies consist of shallow embayment sand shoals. Silty highly protected lagoon fills and shell storm lags are found laterally. During the Wisconsin lowstand of sea level, the area was emergent, and a freshwater swamp developed forming a 1.8 m thick peat. The swamp existed for about 7,000 years, until the leading edge of the Holocene transgression overtopped it. Rapidly rising sea level exceeded sediment supply resulting in the deposition of laminated silts. A barrier island probably had already developed offshore, affording protection for the lagoon. As the rate of sea level rise slowed, the lagoon filled with a coarsening-upward sequence of flasered sands and silts, overla n by a silty sand tidal-flat facies. The lagoonal facies were capped by the barrier island and its associated marshes and tidal creeks. These barrier-related deposits consist of silty marshes and clean sand and shell washovers, inlet fills, and spit platforms. As the system moves landward, much of the lagoonal sequence is truncated at the shoreface, forming a ravinement surface overlain by an offshore sand; however, the Pleistocene deposits and the peat will be preserved below wave base.

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