Aridity-driven decoupling of δ13C between pedogenic carbonate and soil organic matter

Pedogenic carbonate is an invaluable archive for reconstructing continental paleoclimate and paleoecology. The δ13C of pedogenic carbonate (δ13Cc) has been widely used to document the rise and expansion of C4 plants over the Cenozoic. This application requires a fundamental presumption that in soil pores, soil-respired CO2 dominates over atmospheric CO2 during the formation of pedogenic carbonates. However, the decoupling between δ13Cc and δ13C...