Experiments reveal extreme water generation during planet formation

TL;DR

This study experimentally investigates hydrogen-silicate interactions at high pressures and temperatures, revealing significant water production during planet formation, which impacts planetary interior chemistry and atmospheres.

Contribution

It provides novel experimental data on hydrogen and silicate melt reactions at extreme conditions, previously lacking in the field.

Findings

Hydrogen dissolves extensively into silicate melts with temperature dependence.

Reduction of iron oxide produces significant water and iron-enriched blebs.

Planet formation processes likely generate substantial water, affecting planetary structure and atmospheres.

Abstract

The most abundant type of planet discovered in the Galaxy has no analogue in our Solar System and is believed to consist of a rocky interior with an overlying thick H2 dominated envelope. Models have predicted that the reaction between the atmospheric hydrogen and the underlying magma ocean can lead to the production of significant amounts of water. The models suffer however from the current lack of experimental data on the reaction between hydrogen and silicate melt at high pressures and temperatures. Here we present novel experimental results designed to investigate this interaction. Laser heating diamond anvil cell experiments were conducted between 16 and 60 GPa at temperatures above 4000 K. We find that copious amounts of hydrogen dissolve into the silicate melt with a large dependence on temperature rather than pressure. We also find that the reduction of iron oxide leads to the production of significant amounts of water along with the formation of iron-enriched blebs. Altogether, the results predict that the typical processes attending planet formation will result in significant water production with repercussions for the chemistry and structure of the planetary interior as well as the atmosphere.