Carbonate?Associated Phosphate (CAP) Indicates Elevated Phosphate Availability in Neoarchean Shallow Marine Environments

Phosphorus is essential for cell biology, yet scarce in modern marine environments wherein free phosphate consumed by life or titrated calcium to form apatite minerals. The environmental conditions under which the early biosphere emerged and phosphorus was integrated throughout biochemistry unknown. We measured concentrations of 2.8–2.5 Ga shallow carbonate facies across six Neoarchean shelf-ramp environments. found that P/Ca ratios stromatolites, micrites, crystal fans were >4-fold 12-fold more enriched carbonate-associated than coral skeletons abiotic Phanerozoic carbonates. Our results support view Archean productivity limited availability electrons rather other nutrients, help explain why so central molecules, metabolisms, bioenergetics observed cells.