Oxygen isotope fractionation factors involving cassiterite (SnO2): II. Determination by direct isotope exchange between cassiterite and calcite

摘要

Direct oxygen isotope fractionation between cassiterite and calcite has been investigated experimentally at 15 kbar with temperature ranging from 800 to 1000 degrees C. Combined with the quartz-calcite fractionation measured with the same technique (Clayton et al., 1989), the calcite-cassiterite and quartz-cassiterite oxygen isotope fractionations can be expressed as:Delta(CaCO3-SnO2) = 4.14 X 10(6)T(-2)Delta(SiO2-SnO2) = 4.52 X 10(6) T-2at temperatures higher than 600 degrees C. These calibrations are in good agreement with those obtained from heat capacity and X-ray resonant data. The theory of using X-ray resonant data to calculate the reduced partition function ratios of transition elements that have at least one Mossbauer-sensitive isotope is evaluated with the current experimental result. Copyright (c) 2005 Elsevier Ltd.