Biogeosciences www.biogeosciences.net 1726-4170 1726-4189 6 2 2009 10.5194/bg-6-197-2009 http://www.biogeosciences.net/6/197/2009/ http://www.biogeosciences.net/6/197/2009/bg-6-197-2009.html http://www.biogeosciences.net/6/197/2009/bg-6-197-2009.pdf 197 207 2009-02-16 Diagenetic changes in <i>Concholepas concholepas</i> shells (Gastropoda, Muricidae) in the hyper-arid conditions of Northern Chile – implications for palaeoenvironmental reconstructions N. Guzmán Nury.Guzman@ird.fr Y. Dauphin J. P. Cuif A. Denis L. Ortlieb UR 055 Paleotropique, IRD, 32 av. H. Varagnat, 93143 Bondy cedex, France UMR IDES 8148, bât. 504, Université Paris XI-Orsay, 91405 Orsay cedex, France Variations in the chemical composition of fossil biogenic carbonates, and in particular of mollusc shells, have been used in a range of palaeoenvironmental reconstructions. It is of primary importance, therefore, to detect and understand the diagenetic processes that may modify the original chemical signature. This microstructural and biogeochemical study focuses on modern and fossil (Holocene and Pleistocene) 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 mollusc shell biocrystals are complex and might manifest in different ways even within a single individual. The single criterion of determining the mineralogical composition to verify the conservation state of shell samples is insufficient. Adler, H. H.and Kerr, P. F.: Infrared study of aragonite and calcite, Am. Miner., 47, 700–717, 1962. Barskov, I. S., Kiyashko, S. I., Dauphin, Y., and Denis, A.: Microstructures des zones calcitiques et aragonitiques des rostres de \textitGoniocamax (Cephalopoda, Belemnitida) du Turonien de Sibérie du Nord, Geodiversitas, 19, 669–680, 1997. Barth, A.: The infrared absorption of amino acid side chains, Progr. Biophys. Mol. Biol., 74, 141–173, 2000. Böttcher, M. E., Gehlken, P. L., and Steele, D. F.: Characterization of inorganic and biogenic magnesian calcites by Fourier Transform infrared spectroscopy, Solid State Ionics, 101/103, 1379–1385, 1997. Dauphin, Y.: Diagenèse aragonite-calcite chez les Céphalopodes Coléoides: exemples des rostres d'\textitAulacoceras (Trias de Turquie) et \textitBelopterina (Eocène de France), Bull. Mus. Natl. Hist. Nat. Paris, 4e sér., 10, sect. C, 2, 107–135, 1988. Dauphin, Y.: Infrared spectra and elemental composition in recent carbonate skeletons: relationships between the ν2 band wavelength and Sr and Mg concentrations, Appl. Spectr., 51, 141–152, 1997. Dauphin, Y.: Infrared spectra and elemental composition in recent biogenic calcites: relationships between the ν4 band wavelength and Sr and Mg concentrations, Appl. Spectr., 53, 184–190, 1999. Dauphin, Y. and Denis, A.: Analyse microstructurale des tests de Mollusques du Callovien de Lukow (Pologne) – comparaison de l'état de conservation de quelques types structuraux majeurs, Rev. Paléobiol., 9, 27–36, 1990. Dauphin, Y. and Denis, A.: Diagenèse comparée des phases minérales et organiques solubles dans les tests aragonitiques de nautiles et d'ammonites, Bull. Soc. géol. Fr., 170, 355–365, 1999. Dauphin, Y., Guzman, N., Denis, A., Cuif, J. P., and Ortlieb, L.: Microstructure, nanostructure and composition of the shell of \mbox\textitConcholepas \textitconcholepas (Gastropoda, Muricidae), Aquat. Liv. Res., 16, 95–103, 2003. DeNiro, M. J. and Weiner, S.: Chemical, enzymatic and spectroscopic characterisation of "collagen" and other organic fractions from prehistoric bones, Geochim. Cosmochim. Acta, 52, 2197–2206, 1988. DeVries, T., Ortlieb, L., Diaz, A., Wells, L., and Hillaire-Marcel, C.: Determining the early history of El Niño, Science, 276, 965–966, 1997. DuBois, R., Castilla, J. C., and Cacciolatto, R.: Sublittoral observations of behaviour in the chilean "loco" \textitConcholepas \mboxconcholepas (Mollusca: Gastropoda: Muricidae), The Veliger, 23, 83–92, 1980. Falabella, F., Planella, M. T., and Pollastri, A.: Análisis de Oxigeno 18 en material malacológico de Chile Central, XI Congr. Nac. Arqueol. Chilena I, 105–121, 1991. Farmer, V. C.: The Infrared spectra of minerals, Mineral. Soc. Monogr., 4, London, UK, 427 pp., 1974. Guzmán, N.: Validation d'une approche scléroclimatologique sur la côte du Chili et du Pérou par l'analyse microstructurale et biogéochimique des coquilles du gastéropode \textitConcholepas concholepas [Bruguière, 1789], PhD dissertation, Université de Paris-Sud, France, 219 pp., 2004. Harriss, R. C.: Trace element distribution in molluscan skeletal material. I. magnesium, iron, manganese, and strontium, Bull. Mar. Sci., 15, 265–273, 1965. Jones, G. C. and Jackson, B.: Infrared transmission spectra of carbonate minerals, Chapman and Hall, London, UK, 222 pp., 1993. Kennett, D. J.: Oxygen and carbon isotopic analyses of \mbox\textitConcholepas concholepas shells from K4, a late Archaic period archaeological site on the southern coast of Peru, in: Archaeological investigations of K4, an Archaic period site of the south coast of Peru, edited by: Wise, K., Inst. Archaeol., University of California, LA, USA, 1–22, 2003. Labonne, M. and Hillaire-Marcel, C.: Geochemical gradients within modern and fossil shells of \textitConcholepas concholepas, from Northern Chile: An insight into U-Th systematics and diagenetic/authigenic isotopic imprints in mollusc shells, Geochim. Cosmochim. Acta, 64, 1523–1534, 2000. Llagostera, A.: Early occupations and the emergence of fishermen on the Pacific coast of South America, Andean Past, 3, 87–109, 1992. Loreau, J. P.: Sédiments aragonitiques et leur genèse, Mém. Mus. Natl. Hist. Nat. Paris N. S., sér. C, sci terre, 47, 1–312, 1982. Masuda, F. and Hirano, M.: Chemical composition of some modern marine pelecypod shells, Sci. rep. Inst. Geosc., Univ. Tsukuba, B, Geol. Sci., 1, 163–177, 1980. Ortlieb, L., Fuentes, E., Guzman, N., and Llagostera, A.: Paleotemperatura del mar en la Bahia de Antofagasta, durante la transicion Pleistoceno-Holoceno: Resultados preliminares de análisis isotópicos seriados en conchas de \textitConcholepas concholepas, VIII Congr. Geol. Chileno (Antofagasta, 1997), Ext. abstr. vol., 366–370, 1997. Ortlieb, L., Zazo, C., Goy, J. L., Hillaire-Marcel, C., Ghaleb, B., and Cournoyer, L.: Coastal deformation and sea level changes in Northern Chile subduction area (23&deg; S) during the last 330 ky, Quatern. Sc. Rev., 15, 819–831, 1966. Perrier, C., Hillaire-Marcel, C. and Ortlieb, L.: Paléogéographie littorale et enregistrement isotopique ($^13$C, $^18$O) d'événements de type El Niño par les mollusques holocènes et récents du nord-ouest péruvien, Géogr. Phys. Quat., 48, 23–38, 1994. Turekian, K. K. and Armstrong, R. L.: Magnesium, strontium and barium concentrations and calcite-aragonite ratios of some recent molluscan shells, J. Mar. Res., 18, 133–151, 1960. Urey, H. C., Lowenstam, H. A., Epstein, S., and McKinney, C. R.: Measurement of paleotemperatures and temperatures of the Upper Cretaceous of England, Denmark, and the southeastern United States, Geol. Soc. Am. Bull., 62, 399–416, 1951. Venyaminov, S. Y. and Kalnin, N. N.: Quantitative IR spectophotometry of peptide compounds in water (H₂O) solutions. I. Spectral parameters of amino acid residue absorption bands, Biopolymers, 30, 1243–1257, 1990.