The preservation of glacial-interglacial climatic signatures in the oxygen isotopes of elephant skeletal phosphate
Abstract Phosphate δ18O values (δ18Op) of modern elephant bone and teeth are found to vary linearly according to the δ18O of local meteoric water (δ18Omw), a parameter with close ties to regional and local climatic conditions. Enamel, dentine, cementum and bone separates from individual fossil elephant specimens, of Late Pleistocene age, have δOp values which vary by up to elephant specimens. The larger spread in the δ18Op values of the various skeletal phases for the fossil samples is interpreted as evidence for post-depositional alterantion of primary δ18Op signatures of some, if not all, of these fossil skeletal components. In the fossil samples investigated, enamel and dentine phases have systematically lower δ18O values than associated bone and cementum phases. Differential re-equilibration with soil waters, either by the wholesale replacement of primary apatite or by processes of isotopic exchange, is suggested as a mechanism to account for the observed spread in the fossil phosphate δ18O data.