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Surficial sediments of the Great Australian Bight; facies dynamics and oceanography on a vast cool-water carbonate shelf

Noel P. James, Yvonne Bone, Lindsay B. Collins and T. Kurtis Kyser
Surficial sediments of the Great Australian Bight; facies dynamics and oceanography on a vast cool-water carbonate shelf
Journal of Sedimentary Research (July 2001) 71 (4): 549-567

Abstract

The Great Australian Bight (GAB), the largest sector of the southern Australia continental margin, is a site of cool-water carbonate sedimentation throughout, ranging from locally warm-temperate inboard to cool-temperate outboard. Surficial sediments are a mixture of calcareous Pleistocene skeletal and lithic intraclasts (relict grains), and Holocene biofragments, with minor amounts of quartz inboard. The inner shelf is an area of abundant macrophytes and sea-grasses, active carbonate sediment production and accumulation, and little relict sediment. The huge middle portion is a "shaved shelf" with active sediment winnowing and mostly relict sediment. The outer shelf and upper slope is a variably productive sediment factory characterized by prolific calcareous epibenthic growth on hard substrate sub-aqueous "islands" shedding particles into surrounding sands and muds. Patterns of Holocene sedimentation are linked to modern oceanographic parameters in this high-energy setting characterized by overall downwelling. Prolific rhodoliths occur on the NW inner shelf, where shallow summer waters are the warmest in the GAB. These warm, saline, nutrient-depleted waters then drift eastward across the shelf, suppressing heterozoan carbonate production on the central and eastern mid-shelf. This arrested production in the eastern GAB is countered locally by summer coastal upwelling along western Eyre Peninsula, with bryozoan-rich sediment extending well inboard onto the mid-shelf. The outer shelf and upper slope is an area of prolific bryozoan growth, likely linked to upwelling, except in the central GAB, a region of year-round downwelling, where the area is one of off-shelf fine sediment transport and carbonate mud deposition. These patterns, in the central GAB at least, are present in the underlying Holocene and Pleistocene, suggesting that the general modern oceanographic dynamics and resultant carbonate sedimentation have persisted throughout the Quaternary.


ISSN: 1527-1404
EISSN: 1938-3681
Serial Title: Journal of Sedimentary Research
Serial Volume: 71
Serial Issue: 4
Title: Surficial sediments of the Great Australian Bight; facies dynamics and oceanography on a vast cool-water carbonate shelf
Affiliation: Queen's University, Department of Geological Sciences, Kingston, ON, Canada
Pages: 549-567
Published: 200107
Text Language: English
Publisher: Society of Economic Paleontologists and Mineralogists, Tulsa, OK, United States
References: 57
Accession Number: 2001-065559
Categories: Quaternary geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table, sketch maps
S35°00'00" - S31°40'00", E123°30'00" - E135°49'60"
Secondary Affiliation: University of Adelaide, AUS, AustraliaCurtin University, AUS, Australia
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 200120
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