whole-rock X-ray diffraction (XRD) data, carbon and oxygen isotope data, Mn/Sr ratio data, and measured porosity and permeability data of the samples

For another 8 samples with relatively high dolomite contents (>15% dolomite and <54% calcite), the reaction time was shortened to 2 hours to effectively extract the calcite isotopic signals by exploiting the kinetic differences in reaction rates between calcite and dolomite. The results were calibrated against reference standards (GBW04405, IAEA-CO-1-Marble, and IAEA-CO-8-Calcite). The analytical error was less than 0.3‰, and all data are reported relative to the Vienna Pee Dee Belemnite (VPDB) standard.3.

To accurately evaluate the degree of diagenesis and avoid interference from dolomite, 17 samples with high calcite contents (>85% and <12% dolomite) were selected for major and trace element analysis. The analyses were performed at the State Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum (Beijing). Major elements were determined using a ZSX Primus II wavelength-dispersive X-ray fluorescence spectrometer (WD-XRF).

The calibration curves for major element analysis were established using national rock reference materials (GBW07105, GBW07111, and GBW07114-14), and data correction was performed using the theoretical alpha coefficient method, yielding a relative standard deviation (RSD) of <2%. Trace elements were measured using an Agilent 7900 inductively coupled plasma mass spectrometer (ICP-MS). The results were calibrated against reference standards (GSR-3 and JA-2), with an error of less than 0.1 ppm.