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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 67 (1983)

Issue: 3. (March)

First Page: 496

Last Page: 496

Title: Hurricane Influence on Holocene Sediment Accumulation in Sarasota Bay, Florida: ABSTRACT

Author(s): Stephen C. Knowles, Richard A. Davis, Jr.

Article Type: Meeting abstract


Sarasota Bay is a shallow, somewhat ovoid-shaped coastal bay located landward of a Holocene barrier complex on the west-peninsular, microtidal coast of Florida. Sediments presently accumulating in the bay consist of: (1) fine to very fine quartz sand contributed by littoral drift and reworking of older deposits, (2) fine to coarse quartz and phosphatic sand contributed by Tertiary carbonates and Pleistocene terrace deposits, (3) biogenic carbonate debris which is produced within the bay and/or derived from the nearby Gulf of Mexico, and (4) clay minerals derived from weathering of nearby carbonates and shales. Vibracoring throughout the bay has enabled recognition of six subsurface facies: protected bay, open bay, tidal delta-overwash, storm, sand bar, and marsh. Bedrock eneath the bay ranges from 0 to 8 m (26 ft) below present sea level and is largely responsible for the present aerial configuration of Sarasota Bay.

Intense storms (hurricanes) played a prominent role in the Holocene history of the bay. At least three of these extreme events are recorded in the strata that lie beneath the present bay. The storm facies is characterized by fining-upward units of shelly quartz sand each of which ranges up to 1.6 m (5 ft) in thickness. Individual storm deposits may cover as much as 80% (38 km2, 15 mi2) of the bay. These deposits are stratigraphically bracketed by the protected bay and/or open bay facies, which are the other laterally extensive facies present. Washover phenomena and the opening and closing of inlets are also documented in Holocene history and can be related to specific storm units.

The typical stratigraphic sequence of storm and related facies shows the protected bay facies overlain by the storm facies and capped by a combination of the protected bay and open bay facies. Tidal inlet-related facies occur proximal to the barrier and are associated with the storm and protected bay facies, whereas the distal areas are dominated by open bay facies which is reworked, storm-deposited sediment.

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