Minor and trace element incorporation into branching coral Acropora nobilis skeleton

Kotaro Shirai, Tatsunori Kawashima, Kohki Sowa, Tsuyoshi Watanabe, Toru Nakamori, Naoto Takahata, Hiroshi Amakawa, Yuji Sano

Research output: Contribution to journalArticlepeer-review

38 Citations (Scopus)

Abstract

Chemical and isotopic compositions of the Acropora nobilis skeleton were analyzed at various spatial resolutions to investigate the mechanism by which elements are incorporated into the skeleton. Chemical and isotopic profiles along growth axes of axial and radial corallites did not show seasonal variation, with the exception of the δ18O profile of the axial corallite. Detailed observations of the skeletal structure revealed that the skeletal density increased with distance from the tip because secondarily precipitated aragonite (here called the "infilling" skeleton) filled pore spaces in the "framework" skeleton. Microscale element analyses revealed that main part of the infilling skeleton had lower Mg/Ca and higher Sr/Ca and U/Ca than the framework skeleton. At microscale, Sr/Ca and U/Ca were positively correlated with each other, and negatively correlated with Mg/Ca but only weakly. The results showed that the infilling skeleton differed significantly from the adjacent framework skeleton in terms of not only formation chronology but also chemical composition, and that the bulk composition was influenced by the infilling/framework skeletal ratio. In order to use the Acropora skeleton as a paleoclimate archive, the relationship between environmental factors and the chemical composition of each skeletal component needs to be established.

Original languageEnglish
Pages (from-to)5386-5400
Number of pages15
JournalGeochimica et Cosmochimica Acta
Volume72
Issue number22
DOIs
Publication statusPublished - 2008 Nov 15

ASJC Scopus subject areas

  • Geochemistry and Petrology

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