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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 63 (1979)

Issue: 3. (March)

First Page: 527

Last Page: 528

Title: Surface Turbidity and Hydrographic Variability on South Texas Continental Shelf, Gulf of Mexico--Time-Sequence Study: ABSTRACT

Author(s): Gerald L. Shideler

Article Type: Meeting abstract


Regional surface-water turbidity patterns and associated hydrography were monitored on the south Texas continental shelf over an 18-month period (fall 1975 to spring 1977). During six monitoring cruises, quasi-synoptic surface measurements were made of water transmissivity, suspended-sediment concentrations, temperature, salinity, and drifter trajectories. Time-sequence patterns of these parameters illustrate substantial temporal and spatial variability; temporal variations occur at both the seasonal and annual time scales.

Turbidity and hydrographic patterns indicate a surface-sediment dispersal system regulated by a shelf-water exchange process consisting of opposing lateral movements of inner-shelf and outer-shelf water masses. Relatively turbid inner-shelf waters reflect the offshore and alongshore transport of coastal-derived sediment. The inner shelf has a regional gradient of shoreward-increasing turbidity; superimposed local gradients are established at major tidal inlets that serve as prominent

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sediment point sources and dispersal centers. Turbidity variability along the inner shelf is jointly attributed to variations in coastal runoff, relative tidal sediment flux from individual inlets, and ambient wind-induced hydrographic conditions. The outer-shelf patterns suggest the shelfward incursion of open-ocean waters, the extent of which varies spatially and temporally. Regional turbidity patterns appear to reflect the degree of interchange between the gulfward movement of turbid inner-shelf waters and the shelfward incursion of clear open-ocean waters. The observed variability is compatible with a conceptual model of the regional dispersal system based on seafloor sediment distribution, which suggests both net offshore and net southward alongshore transport on a wind-dominated shelf.

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Copyright 1997 American Association of Petroleum Geologists