Graduate School of Social and Cultural Studies, Kyushu University
Abstract
Oxygen isotopic composition of carbonate has been considered as the most reliable thermometer for ancient water environments because of temperature-dependency of the fractionation factor between carbonate and water. However, the temperature-dependency is not always guaranteed, and the fractionation factor is variable with pH that controls relative abundance among different dissolved carbonate species. This chemical systematics was first verified by a German geochemist, Eberhard Usdowski. We review his work on temperature-independency in oxygen isotopic fractionation, and note that our data from an Indonesian hot spring are consistent with his model
