Oxygen isotope fractionation between crocodilian phosphate and water

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• 作者：Romain Amiot ; Christophe Lé ; cuyer ; Gilles Escarguel ; Jean-Paul Billon-Bruyat ; Eric Buffetaut ; Cyril Langlois ; Samuel Martin ; Franç ; ois Martineau ; Jean-Michel Mazin
• 关键词：Crocodile ; Turtle ; Oxygen isotopes ; Fractionation ; Paleoecology
• 刊名：Palaeogeography ; Palaeoclimatology ; Palaeoecology
• 出版年：2007
• 期刊代码：68_00310182
• 类别：ear
• 出版时间：22 January 2007
• 卷：243
• 期：3-4
• 页码：412-420
• 文件大小：418 K

摘要

Oxygen isotope compositions of phosphate (δ¹⁸O_p) were measured in tooth enamel from captive and wild individuals of 8 crocodilian species. A rough linear correlation is observed between the δ¹⁸O_p of all the studied species and the oxygen isotope composition of ambient water (δ¹⁸O_w). Differences in mean air temperature, diet and physiology could contribute significantly to the large scatter of δ¹⁸O_p values. The combination of these parameters results in a fractionation equation for which the slope (0.82) is lower than that expected (≥ 1) from predictive model equations that assume temperature and diet as fixed parameters. Taking into account large uncertainties, the observed oxygen isotope fractionation between phosphate and ambient water does not statistically differ from that formerly established for aquatic turtles. Case studies show that δ¹⁸O_p values of fossil crocodile tooth enamel can be used to discriminate between marine and freshwater living environments within a precision of about ± 2‰ only.