New constraints on the origin of the Australian Great Barrier Reef: results from an international project of deep coring
Alexander, I., Wilson, P.A., Cooper, M.J. and International Consortium Great Barrier Reef Drilling (2001) New constraints on the origin of the Australian Great Barrier Reef: results from an international project of deep coring. Geology, 29, (6), 483-486. (doi: 10.1130/0091-7613(2001)029<0483:NCOTOO>2.0.CO;2).
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Two new boreholes provide the first direct evidence of the age of the Australian Great Barrier Reef. An inner shelf sequence (total depth, 86 m; basal age = 210 ± 40 ka) comprises a dominantly siliciclastic unit (thickness 52–86 m), overlain by four carbonate units (total thickness 0–34 m). A shelf-edge and slope sequence (total depth 210 m) reveals three major sections: (1) a lower section of resedimented flows deposited on a lower slope, (2) a mid-section including intervals of corals, rhodoliths, and calcarenites with low- angle graded laminae, and (3) an upper section of four shelf- margin coral-reef units separated by karst surfaces bearing paleosols. Sr isotope and magnetostratigraphic data indicate that the central Great Barrier Reef is relatively young (post Brühnes-Matuyama boundary time), and our best estimate for the onset of reef growth on the outer barrier system is ca. 600 ± 280 ka. This date suggests that reef initiation may have been related to the onset of full eccentricity-dominated glacio-eustatic sea-level oscillation as inferred from large-amplitude “saw-tooth‿ 100 k.y. δ18O cycles (after marine isotope stage 17), rather than to some regional environmental parameter. A major question raised by our study is whether reef margins globally display a similar growth history. The possibility of a global reef initiation event has important implications for basin to shelf partitioning of CaCO3, atmospheric carbon dioxide levels, and global temperature change during Quaternary time.
|Keywords:||INTERNATIONAL CONSORTIUM FOR GREAT BARRIER REEF DRILLING, CARBONATE SEDIMENTS, DIAGENESIS, REEFS, SEA LEVEL, GEOLOGY|
|Subjects:||Q Science > QE Geology
G Geography. Anthropology. Recreation > GC Oceanography
|Divisions:||University Structure - Pre August 2011 > School of Ocean & Earth Science (SOC/SOES)
|Date Deposited:||10 Aug 2004|
|Last Modified:||25 Apr 2013 08:54|
|RDF:||RDF+N-Triples, RDF+N3, RDF+XML, Browse.|
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