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Origin of mixed carbonate and siliciclastic sequences at the margin of a "giant" platform during the Quaternary (Bonaparte Basin, NW Australia)

Julien Bourget, R. Bruce Ainsworth and Rachel Nanson
Origin of mixed carbonate and siliciclastic sequences at the margin of a "giant" platform during the Quaternary (Bonaparte Basin, NW Australia) (in Deposits, architecture and controls of carbonate margin, slope, and basinal settings, Klaas Verwer (editor), Ted E. Playton (editor) and Paul M. Harris (editor))
Special Publication - Society for Sedimentary Geology (2013) 105: 157-177

Abstract

A 630-km-wide continental shelf characterized by mixed carbonate and siliciclastic sedimentation formed during the Quaternary across the Bonaparte Basin, NW Australia. During this time interval ( approximately 2.6 million years), shelf-margin and slope deposits were disconnected from the inner shelf and hinterland by the 200-km-wide, low-gradient Malita intrashelf basin. In this study, two-dimensional (2D) and three-dimensional (3D) seismic, well log, and core data were used to determine the relative importance of allogenic and autogenic controls on the stratigraphic architecture of shelf-edge and slope deposits at multiple timescales. This work has determined that Quaternary sea-level variations (glacio-eustasy) provided a primary control on the stratigraphic evolution of shelf-margin and slope deposits. The early Quaternary period was marked by the aggradation and progradation of a carbonate margin under global sea-level highstand conditions. The onset of high-amplitude sea-level fluctuations at the Mid-Pleistocene Transition (ca. 0.9 Ma BP) enhanced the development of a mixed clastic-carbonate margin and slope system. During the late Quaternary, long-duration sea-level falls and lowstands and high rates of terrigenous sediment supply resulted in stacked fourth-and fifth-order systems tracts in the form of prograded shelf-margin and slope wedges. Conversely, rapid, high-amplitude, fourth- and fifth-order transgressions between these time intervals enhanced the aggradation of carbonate buildups at the shelf edge. Hence, high-frequency sea-level changes resulted in reciprocal sedimentation similar to many other mixed depositional systems of the late Quaternary. However, the main locus of carbonate and mixed deposition across the Bonaparte Basin shelf margin and slope varied spatially at longer times scales. Indeed, conventional seismic data have revealed that the third-order systems tracts at two separate locations in the Bonaparte Basin (eastern and northwestern shelf-margin) show stratigraphic asymmetry (rimmed carbonate margin vs. shelf-margin and slope progradation), which reversed during the late Quaternary. Our results suggest that this reversal in the locus of carbonate vs. mixed sedimentation was related to the shift of the detrital feeder system (the Malita tidal valley) during a major sea-level fall of the late Quaternary (tentatively ascribed to the ca. 0.6 Ma BP lowstand). This study illustrates the importance of both allogenic and autogenic parameters in controlling the stratigraphic architecture of shelf-margin and slope deposits at multiple timescales, in a very wide, mixed carbonate and clastic depositional setting.


ISSN: 1060-071X
EISSN: 2159-5755
Serial Title: Special Publication - Society for Sedimentary Geology
Serial Volume: 105
Title: Origin of mixed carbonate and siliciclastic sequences at the margin of a "giant" platform during the Quaternary (Bonaparte Basin, NW Australia)
Title: Deposits, architecture and controls of carbonate margin, slope, and basinal settings
Author(s): Bourget, JulienAinsworth, R. BruceNanson, Rachel
Author(s): Verwer, Klaaseditor
Author(s): Playton, Ted E.editor
Author(s): Harris, Paul M.editor
Affiliation: University of Western Australia, School of Earth and Environment, Crawley, West. Aust., Australia
Affiliation: Statoil, Bergen, Norway
Pages: 157-177
Published: 2013
Text Language: English
Publisher: Society for Sedimentary Geology (SEPM), Tulsa, OK, United States
ISBN: 978-1-56576-323-4
Meeting name: Deposits, architecture and controls of carbonate slope and basinal settings
Meeting location: Long Beach, CA, USA, United States
Meeting date: 201205May 2012
References: 83
Accession Number: 2015-100254
Categories: Quaternary geologySedimentary petrology
Document Type: Serial Conference document
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., sketch maps
S15°00'00" - S09°00'00", E125°00'00" - E131°00'00"
Secondary Affiliation: Chevron Energy Technology Company, USA, United StatesUniversity of Adelaide, AUS, Australia
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 201543
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