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

Alexander L. Thomas, Kazuhiko Fujita, Yasufumi Iryu, Edouard Bard, Guy Cabioch, Gilbert Camoin, Julia E. Cole, Pierre Deschamps, Nicolas Durand, Bruno Hamelin, Katrin Heindel, Gideon M. Henderson, Andrew J. Mason, Hiroki Matsuda, Lucie Ménabréaz, Akitoshi Omori, Terry Quinn, Saburo Sakai, Tokiyuki Sato, Kaoru SugiharaYasunari Takahashi, Nicolas Thouveny, Alexander W. Tudhope, Jody Webster, Hildegard Westphal, Yusuke Yokoyama

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)

Abstract

We present uranium-thorium chronology for a 102m 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 δ 18O 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 0.39mka -1, with the most likely rate being close to the existing minimum estimate of 0.25mka -1.

Original languageEnglish
Pages (from-to)86-94
Number of pages9
JournalMarine Geology
Volume295-298
DOIs
Publication statusPublished - 2012 Feb 15

Keywords

  • Coral
  • IODP Expedition 310
  • Island subsidence
  • Open system
  • Paleo water-depth
  • Tahiti
  • U-Th

ASJC Scopus subject areas

  • Oceanography
  • Geology
  • Geochemistry and Petrology

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