Clumped isotope geochemistry of island carbonates in the South China Sea: Implications for early diagenesis and dolomitization

Studying the diagenesis of island carbonates can be hampered by difficulty accurately constraining mineral formation temperature. The carbonate clumped isotope composition (measured as ?47 value) is based on temperature-dependent binding 13C to 18O, and offers a promising means calculating In this study, we report values from ~1 km-long drill core Meiji Reef in South China Sea, which are integrated with petrography, carbon (?13C) oxygen (?18O) compositions, trace element contents constrain diagenetic environment. We find that most digenetic alteration initial likely occurred above water depth ~200 m below sea level at temperatures between ~15 28 °C, fluids involved during calcites dolomites have similar ?18O modern seawater. Considering estimated secular variation seawater ?18O, dolomite formed an evaporative fluid source via brine reflux mechanism high convection rate late Miocene. Although isotopic compositions reef were overprinted early alteration, reflect temperature their depositional environment if depths depth. These results help refine existing dolomitization model tropical islands increase utility shallow burial settings valuable records climate conditions.