# Magmatic and thermally produced reactive phosphorus 3.2 billion years ago and its implications for early life

## TL;DR

This study shows that magmatic and thermal processes 3.2 billion years ago could have produced reactive phosphorus, which may have been important for the origin of life.

## Contribution

The study provides geological evidence of magmatic and thermally produced reactive phosphorus in ancient rocks and demonstrates how carbon can aid in their formation.

## Key findings

- Magmatic phosphite and metamorphic polyphosphate were detected in 3.22 Ga Moodies Group rocks.
- Carbon facilitates thermal production of polyphosphates and reduced phosphorus species from minerals like apatite.
- These findings suggest magmatic and thermal rocks could have supplied essential phosphorus for early life.

## Abstract

Reduced and polymerized phosphorus species may have been crucial for the origin and early evolution of life, as they are more reactive and soluble than phosphate. Thermal processes could have produced these phosphorus species; however, the underlying mechanism is poorly constrained, and geological evidence of polymerized species in the Precambrian is so far absent. Here, we investigated contact-metamorphic rocks from the ca. 3.22 Ga Moodies Group (South Africa), where mafic dikes intruded into shallow-marine sediments. We provide evidence of magmatic phosphite (up to 2.85 ppm) and metamorphic polyphosphate (up to 39.3 ppm). Additional laboratory experiments suggest that carbon can facilitate the thermal production of polyphosphates and reduced phosphorus species, including phosphide, from less reactive minerals such as apatite and vivianite. We conclude that magmatic and thermal-metamorphic rocks could have provided soluble and reactive phosphorus species crucial for the origin and early evolution of life.

Carbon can aid thermal production of polyphosphates and reduced phosphorus species from less reactive minerals, suggesting magmatic and thermal-metamorphic rocks may have provided essential phosphorus species for life origin, according to high-temperature experiments and analysis of metamorphic rocks from the 3.22 Ga Moodies Group in South Africa.