Limits of calcium isotopes diagenesis in fossil bone and enamel

Autor: Dodat, Pierre-Jean, Martin, Jeremy, Olive, Sébastien, Hassler, Auguste, Albalat, Emmanuelle, Boisserie, Jean-Renaud, Merceron, Gildas, Souron, Antoine, Maureille, Bruno, Balter, Vincent
Přispěvatelé: Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), De la Préhistoire à l'Actuel : Culture, Environnement et Anthropologie (PACEA), Université de Bordeaux (UB)-Centre National de la Recherche Scientifique (CNRS), Royal Belgian Institute of Natural Sciences (RBINS), Laboratoire de paléontologie, évolution, paléoécosystèmes, paléoprimatologie (PALEVOPRIM ), Université de Poitiers-Centre National de la Recherche Scientifique (CNRS), Centre Français des Études Ethiopiennes (CFEE), Ministère de l'Europe et des Affaires étrangères (MEAE)-Centre National de la Recherche Scientifique (CNRS), CNRS 80| PRIME program and Research Program of the Nouvelle Aquitaine Re- gion: Isotopes du calcium et anthropobiologie au Pal ́eolithique moyen, convention n◦ 2019-1R40208, European Project: 101032456-TNT,TNT
Rok vydání: 2023
Předmět:
Zdroj: Geochimica et Cosmochimica Acta
Geochimica et Cosmochimica Acta, 2023, 351, pp.45-50. ⟨10.1016/j.gca.2023.04.012⟩
ISSN: 0016-7037
Popis: International audience; Diagenesis has been recognized for decades to significantly alter the trace elements biogenic signatures in fossil tooth enamel and bone that are routinely used for paleobiological and paleoenvironmental reconstructions. This signature is modified during diagenesis according to a complex continuum between two main processes, addition and substitution. For an additive-like, or early diagenesis, the trace elements biogenic profiles can be restored by leaching secondary minerals, but this technique is inefficient for a substitutive-like, or extensive diagenesis for which secondary trace elements are incorporated into the biogenic mineral. This scheme is however unclear for Ca, the major cation in tooth enamel and bone hydroxylapatite, whose stable isotope composition (δ44/42Ca) also conveys biological and environmental information. We present a suite of leaching experiments for monitoring δ44/42Ca values in artificial and natural fossil enamel and bone from different settings. The results show that enamel δ44/42Ca values are insensitive to an additive-like diagenesis that involves the formation of secondary Ca-carbonate mineral phases, while bone shows a consistent offset toward 44Ca-enriched values, that can be restored to the biogenic baseline by a leaching procedure. In the context of a substitutive-like diagenesis, bone exhibits constant δ44/42Ca values, insensitive to leaching, and shows a REE pattern symptomatic of extensive diagenesis. Such a REE pattern can be observed in fossil enamel for which δ44/42Ca values are still fluctuating and follow a trophic pattern. We conclude that Ca isotopes in fossil enamel are probably not prone to extensive diagenesis and argue that this immunity is due to the very low porosity of enamel that cannot accommodate enough secondary minerals to significantly modify the isotopic composition of the enamel Ca pool.
Databáze: OpenAIRE
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