Stable isotope geochemistry of carbonate fracture fills in the Monterey Formation, California

Isotope systematics can be interpreted in terms of δ¹⁸O values that were controlled by crystallization temperatures and the δ¹⁸O of connate pore water, and δ¹³C values that were controlled by depth-sequential organic matter degradation reactions. Each successive generation of carbonate precipitated at progressively higher burial temperatures from isotopically evolving connate pore water. These carbonate-filled fractures developed during burial and not during uplift. Using crystallization temperature estimates from fluid inclusion data, the change in δ¹⁸O of conate pore water with increasing temperature in the burial environment is modeled. -from Authors