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The environment recording unit in coral skeletons: structural and chemical evidences of a biochemically driven stepping-growth process in coral fibres
1Université Paris XI-Orsay, Bat. 504, Géologie ,UMR IDES, F-91405 Orsay, France
2Université Paris VI-UPMC, Micropaléontologie, t. 46–56 E5, 4 place Jussieu, UMR IDESF, F-75252 Paris cedex 05, France
Abstract. To improve our understanding of the environment recording by scleractinian corals, a detailed study of the skeleton microstructure has been carried out. A series of physico-chemical in situ characterizations was made, an approach that provides us with structural and biochemical information at the micrometric and nanometric scales. Gathering of these data results in a significant change in our concept of the growth of coral skeletons. In contrast to the usual view of an aggregate of purely mineral units (the coral fibres) independently growing by a simple chemical precipitation, coral skeletons appear to be biochemically controlled structures. Both structural and biochemical data reveal the micron-scaled stepping growth-mode of fibres, and its global coordination. In this process, sulfated acidic proteoglycans probably play a major role, due to their ability to create polymeric frameworks. Atomic force microscopy confirms the close relationship of organic and mineral phases at the nanometric scale.
A new microstructural model of coral skeleton formation is proposed, that places coral skeletons among the typical "matrix mediated structures". From a practical standpoint, these results may contribute to develop a new high resolution approach in the study of paleoenvironments.
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Citation: Cuif, J. P. and Dauphin, Y.: The environment recording unit in coral skeletons: structural and chemical evidences of a biochemically driven stepping-growth process in coral fibres, Biogeosciences Discuss., 1, 625-658, 2004. Bibtex EndNote Reference Manager
