New constraints on the kinetics of 13C-18O bond reordering

Coupling experiments and data from contact metamorphic aureoles of magmatic intrusions

In addition to the analytical developments, there is still a pressing need to solve some fundamental questions in clumped isotope geochemistry of carbonates before this method can be applied with more confidence. Among those questions, the fractionation factor for the phosphoric acid reaction for different mineralogies had not been determined experimentally yet. In addition the available temperature calibrations for clumped isotopes are mostly limited to temperatures below 90°C, and the kinetics of alteration of clumped isotope signatures through bond reordering upon heating during burial diagenesis needs further testing for different materials and mineralogies. These questions are fundamental in order to improve the applicability of carbonate clumped isotopes for paleoclimate reconstruction in deep time, as well as for the study of diagenetic processes and tectonics. We are coupling studies of the alteration of clumped isotope signatures around contact metamorphic aureoles of various intrusions, determining an new temperature calibration for dolomite, and conducting reordering experiments in the laboratory. Furtheremore we are using clumped isotopes to deteremine the temperature and composition of fluids associated with major seismically active faults in Italy.