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doi:10.2204/iodp.proc.307.201.2009

Data report: geochemical characterization of a lithified horizon of Challenger Mound, Hole U1317B¹

Chizuru Takashima,² Masako Hori,³ and Akihiro Kano²

Abstract

The sediments of Challenger Mound, drilled during Integrated Ocean Drilling Program Expedition 307, show alternations of darker and lighter colored layers in ~10 m intervals. Lithified horizons often observed in the lighter layers were interpreted as deposits of interglacial periods. We performed high-resolution analysis of minor elements (Mg and Sr) and stable isotopes for 33 cm long sections that contain lithified horizons. The Sr/Ca ratio, carbonate content, and oxygen and carbon stable isotopes show significant correlation to one another. We also observed mottled parts composed of framboidal pyrites at the levels where carbonate contents and Sr/Ca ratios are high. The results suggest an association among coral skeletons, bacterial sulfate reduction, and carbonate precipitation. It is suggested that sulfate-reducing bacteria were responsible for decomposing organic matter in coral skeletons and induced the precipitation of carbonate.

¹Takashima, C., Hori, M., and Kano, A., 2009. Data report: geochemical characterization of a lithified horizon of Challenger Mound, Hole U1317B. In Ferdelman, T.G., Kano, A., Williams, T., Henriet, J.-P., and the Expedition 307 Scientists, Proc. IODP, 307: Washington, DC (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/​iodp.proc.307.201.2009

²Graduate School of Social and Cultural Studies, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan. Correspondence author: ctakashima@scs.kyushu-u.ac.jp

³Department of Earth and Planetary Systems Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-hiroshima 739-8526, Japan.

Initial receipt: 7 June 2008
Acceptance: 14 April 2009
Publication: 16 June 2009
MS 307-201

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