Sulfur mass-independent fractionation in subsurface fracture waters indicates a long-standing sulfur cycle in Precambrian rocks

Abstract

Precambrian rocks host a deep hydrosphere, but where dissolved sulfate, crucial for microbial life, comes from is unclear. At 2.4 km depth in the Canadian shield, Li et al. find that oxidation of sulfides in the host rocks creates sulfate thus providing a long-term mechanism for the deep biosphere sulfate.