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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 57 (1973)

Issue: 4. (April)

First Page: 784

Last Page: 784

Title: Physical and Biogenic Characteristics of Sediments from Outer Georgia Continental Shelf: ABSTRACT

Author(s): James D. Howard, Robert W. Frey, Frank A. Kingery

Article Type: Meeting abstract


Eighty-eight box cores were taken on the outer Georgia continental shelf, in water depths from 15 to 200 m. Textural analysis indicates that the midshelf area is covered by medium to coarse sand, evenly distributed, with no north-south linear trends. Areas of fine sand are present on the inner and outer shelf edges, and in 2 distinct lobes extending seaward from the Georgia coast. Parts of the lobes suggest that the finer material forming them was supplied by the Savannah and Altamaha Rivers. Local patches of semiconsolidated mud indicate the location of remnant marsh or estuary deposits.

Offshore shell assemblages indicate a mixing of faunas in terms of both environment and age. Pleistocene regressions and transgressions across the shelf resulted in alternate oceanward and landward migrations of nearshore and estuarine faunas, reworked subsequently with open-ocean faunas. Live animals offshore are adding their shells to the already mixed assemblages.

Biogenic sedimentary structures significantly exceed those of primary physical structures. All box cores show some degree of biogenic reworking, and most were more than 60% bioturbated. Physical sedimentary structures include crossbedding, ripple lamination, interbedded sand and mud, wavy bedding, and graded bedding.

Physical and biogenic reworking of the outer Georgia continental shelf sediments has removed or greatly modified most of their original depositional characteristics. Thus, reference to these sediments as "relict" is misleading.

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