Micritization mechanism in penecontemporaneous carbonate rocks: coupled C- Ca cycles and constraints from diagenetic environments

1.This dataset was collected to investigate the hypothesis that early meteoric diagenesis—specifically micritization in isolated carbonate platforms—is driven by an interface-coupled dissolution-precipitation mechanism rather than traditional microboring organisms. We hypothesize that hydrologically controlled zonations exert distinct kinetic controls on fluid-mineral interactions, which are faithfully recorded in the isotopic (C, O, Ca, Sr) and trace element signatures of the diagenetic products.
2.The dataset comprises geochemical, isotopic, and trace element data derived from coral reef limestone samples from a South China Sea isolated atoll. Powdered samples of unaltered precursors and micritized products were obtained using a high-precision micro-drill. Samples underwent sequential acetic acid leaching to remove secondary carbonates. Strontium and Calcium isotopic ratios were measured using a Thermo Fisher Triton XT thermal ionization mass spectrometer. Trace elements (including Al, Th, Sc, P, Fe, Mn, and REE+Y) were analyzed via ICP-MS to evaluate terrigenous contamination and redox conditions. Data quality was strictly monitored using certified reference materials.
3.The data reveal several key diagenetic patterns. The 87Sr/86Sr ratios of intensely micritized samples are nearly indistinguishable from unaltered precursors, indicating a rock-buffered system that inherited coeval marine Sr signatures. A pronounced negative excursion in δ44/40Ca is exclusively observed in the intensely micritized phreatic zone, coupled with significant Sr depletion. Trace element analyses confirm the pristine nature of the samples, devoid of significant terrigenous or hydrothermal contamination.
4. These data should be interpreted within the framework of reactive-transport and fluid-mineral kinetics. The pronounced δ44/40Ca negative excursion, combined with stable Sr isotopes, serves as a unique in situ tracer for rapid, non-equilibrium crystallization driven by the ICDP mechanism in a restricted fluid environment.
5. Researchers can utilize this dataset to: (1) model early meteoric diagenesis and element partitioning in deep-time carbonate systems; (2) distinguish kinetic isotope effects from primary environmental signals in chemostratigraphy; (3) conduct global cross-regional correlations.