Mafic-ultramafic igneous rocks as a source of reactive phosphorus for the origin of life

Reduced and polymerized phosphorus species such as phosphite and pyrophosphate may have been crucial prebiotic substrates due to their higher reactivity and greater solubility, yet their sources remain debated and fluxes poorly constrained. Here, we show that mafic–ultramafic rocks on the early Earth could serve as a geologically sustainable source of reactive phosphorus via seafloor weathering. Analysis of mafic-ultramafic rocks from 15 locations reveals phosphite accounting for up to 7%, 24%, 17%, and 0.6% of total extracted phosphorus in olivine separates, peridotite, komatiite, and basalt, respectively, while pyrophosphate reached up to 5% and 0.4% in komatiite and basalt. Using a box model, we show that phosphite could have reached 1 µM in the deep ocean and 67 µM in lakes under low ultra-violet conditions on the prebiotic Earth. We conclude that mafic-ultramafic rocks on the early Earth and possibly other planetary bodies could be an important source of reactive phosphorus for the origin and early evolution of life.