Successive phases of serpentinization and carbonation recorded in the Sivas ophiolite (Turkey), from oceanic crust accretion to post-obduction alteration

The ophiolite of Sivas (Turkey) was studied in order to define the chronology different alteration events related a series serpentinization and carbonation episodes. Six samples were investigated, representative types ophicalcite (partially carbonated serpentinite). X-ray diffraction (XRD) Mössbauer spectroscopy used determine bulk mineralogy Fe 3+ /Fe tot ratio, respectively. Electron microprobe secondary ion mass spectrometer (SIMS) analyses also conducted identify chemical composition mineral phases addition carbon oxygen isotopic compositions calcite. An initial, i.e. pre-obduction, phase olivine pyroxene followed by brecciation event associated with precipitation massive serpentine. This first occurred during exhumation peridotites seafloor, at temperatures range 35‒100 °C. A low-temperature (∼35 °C) between 90 65 Ma. Finally, reheating system likely after obduction 55‒40 Ma, resulting episode late serpentinization. Our study presents direct evidence obduction. In that geological context, hydrogen produced proposed multiphase may have been trapped salt deposits overlying but subsurface data will be necessary potential traps reservoirs; further studies are needed whether process is still ongoing.