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Diagenetic changes in Concholepas concholepas shells (Gastropoda, Muricidae) in the hyper-arid conditions of Northern Chile – implications for palaeoenvironmental reconstructions
1UR 055 PALEOTROPIQUE, IRD, 32 av. H. Varagnat, 93143 Bondy cedex, France
2UMR IDES 8148, bât. 504, Université Paris XI-Orsay, 91405 Orsay cedex, France
Abstract. Variations on chemical composition in fossil biogenic carbonates, and in particular of mollusk shells, have been used in a range of palaeoenvironmental reconstructions. Therefore, it is of primary importance to detect and understand the diagenetic processes that may modify the original chemical signature. This microstructural and biogeochemical study focuses on modern and fossil (Pleistocene and Holocene) shells of a littoral gastropod of Northern Chile, and on the characterization of mineral component transformations at the nanometric scale and concomitant intracrystalline organic compound modifications. The inner aragonite layer of the shell exhibits more complex deteriorations than the calcite layer. This preliminary study confirms that physical and chemical alterations of various components of mollusk shell biocrystals are complex and might manifest in different ways even within a single individual. The single criterion of determining the mineralogical composition to attest shell sample conservation state should not be considered as sufficient.
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Citation: Guzman, N., Dauphin, Y., Cuif, J. P., Denis, A., and Ortlieb, L.: Diagenetic changes in Concholepas concholepas shells (Gastropoda, Muricidae) in the hyper-arid conditions of Northern Chile – implications for palaeoenvironmental reconstructions, Biogeosciences Discuss., 5, 501-530, 2008. Bibtex EndNote Reference Manager
