Assessing subsidence rates and paleo water-depths for Tahiti reefs using U-Th chronology of altered corals

Thomas, Alexander L., Fujita, Kazuhiko, Iryu, Yasufumi, Bard, Edouard, Cabioch, Guy, Camoin, Gilbert, Cole, Julia E., Deschamps, Pierre, Durand, Nicolas, Hamelin, Bruno, Heindel, Katrin, Henderson, Gideon M., Mason, Andrew J., Matsuda, Hiroki, Menabreaz, Lucie, Omori, Akitoshi, Quinn, Terry, Sakai, Saburo, Sato, Tokiyuki, Sugihara, Kaoru, Takahashi, Yasunari, Thouveny, Nicolas, Tudhope, Alexander W., Webster, Jody, Westphal, Hildegard, and Yokoyama, Yusuke (2012) Assessing subsidence rates and paleo water-depths for Tahiti reefs using U-Th chronology of altered corals. Marine Geology, 295-298. pp. 86-94.

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Abstract

We present uranium-thorium chronology fora 102 m core through a Pleistocene reef at Tahiti (French Polynesia) sampled during IODP Expedition 310 "Tahiti Sea Level". We employ total and partial dissolution procedures on the older coral samples to investigate the diagenetic overprint of the uranium-thorium system. Although alteration of the U-Th system cannot be robustly corrected, diagenetic trends in the U-Th data, combined with sea level and subsidence constraints for the growth of the corals enables the age of critical samples to be constrained to marine isotope stage 9. We use the ages of the corals, together with δ¹⁸O based sea-level histories, to provide maximum constraints on possible paleo water-depths. These depth constraints are then compared to independent depth estimates based on algal and foraminiferal assemblages, microbioerosion patterns, and sedimentary facies, confirming the accuracy of these paleo water-depth estimates. We also use the fact that corals could not have grown above sea level to place a maximum constraint on the subsidence rate of Tahiti to be 0.39 m ka⁻¹, with the most likely rate being close to the existing minimum estimate of 0.25 m ka⁻¹.

Item ID: 22631
Item Type: Article (Research - C1)
ISSN: 0025-3227
Keywords: paleo water-depth, Tahiti, IODP Expedition 310, island subsidence, coral, U-Th, open system
Date Deposited: 01 Aug 2012 09:22
FoR Codes: 04 EARTH SCIENCES > 0403 Geology > 040305 Marine Geoscience @ 30%
04 EARTH SCIENCES > 0406 Physical Geography and Environmental Geoscience > 040605 Palaeoclimatology @ 35%
04 EARTH SCIENCES > 0406 Physical Geography and Environmental Geoscience > 040606 Quaternary Environments @ 35%
SEO Codes: 96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960503 Ecosystem Assessment and Management of Coastal and Estuarine Environments @ 35%
96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960507 Ecosystem Assessment and Management of Marine Environments @ 35%
97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 30%
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