Facies and diagenesis of older Pleistocene coral reefs, Great Barrier Reef, Australia (IODP 325)

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Author(s): Gischler, Eberhard; Droxler, Andre W.; Webster, Jody
Integrated Ocean Drilling Program, Expedition 325 Scientists, Edinburgh
Author Affiliation(s): Primary:
Goethe University, Geosciences, Frankfurt, Germany
Other:
Rice University, United States
University of Sydney, Australia
Volume Title: 2011 AAPG annual convention & exhibition; abstracts volume
Source: Abstracts: Annual Meeting - American Association of Petroleum Geologists, Vol.2011; AAPG 2011 annual convention & exhibition, Houston, TX, April 10-13, 2011. Publisher: American Association of Petroleum Geologists and Society for Sedimentary Geology, Tulsa, OK, United States
Note: In English
Summary: IODP expedition 325 drilled 34 holes along four traverses across the Great Barrier Reef of Australia thereby penetrating some 750 m of reefal deposits of the late Quaternary in water depths ranging from 40-170 m. The expedition took place during 12 February - 1 April and was followed by the onshore science party in Bremen, Germany, during 1-16 July 2010 involving 28 scientists from 9 countries. IODP expedition 325 has three major objectives. They include (1) a reconstruction of deglacial sea level for the period 20-10 kyrs BP with a focus on MWP 1A and 1B events, (2) to use the variability of sea surface temperature and sea-level change on reef growth patterns including drowning, and (3) to quantify paleoclimatic change in high-resolution by sampling skeletons of massive corals during the same time window. According to preliminary age dating, the majority of cores cover the time period of about 25-10 kyrs BP. These late Pleistocene sections appear diagenetically unaltered and comprise coralgal boundstone, coralgal-microbial boundstone, skeletal grainstone and rudstone, and unconsolidated sand. In five cores taken in depths of 40-85 m water depths at three traverses, older Pleistocene (>25 Kyrs BP) reefal deposits were recovered in lower core sections. Lithologies include skeletal grainstone to rudstone, some packstone, coralgal boundstone, and few occurrences of coral-microbial boundstone. Usually, they exhibit clear evidence of diagenetic modification in the meteoric realm, such as caliche phenomena, neomorphism, dissolution vugs, and low magnesium calcite cement growth. Samples are currently being investigated under sedimentologic and diagenetic aspects, and detailed results will be presented at the meeting.
Year of Publication: 2011
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Boreholes; Boundstone; Carbonate rocks; Cenozoic; Coral Sea; Cores; Deglaciation; Diagenesis; Expedition 325; Expeditions; Facies; Grainstone; Great Barrier Reef; Great Barrier Reef Environmental Changes; Integrated Ocean Drilling Program; Pacific Ocean; Packstone; Paleoclimatology; Pleistocene; Quaternary; Reconstruction; Reefs; Rudstone; Sea-level changes; Sea-surface temperature; Sedimentary rocks; South Pacific; Southwest Pacific; Upper Quaternary; West Pacific
Coordinates: S195100 S152800 E1502900 E1454900
Record ID: 2015042207
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