Pressure-temperature Phase Diagram of the Earth

TL;DR

This study models Earth's pressure-temperature phase diagram to identify the deepest liquid water environments and estimate the extent of habitable zones within Earth's interior.

Contribution

It provides a detailed P-T phase diagram of Earth, highlighting the depth of liquid water and the distribution of inhabited versus uninhabited liquid water regions.

Findings

Deepest liquid water at ~75 km depth

Approximately 3.5% of Earth's volume contains liquid water

About 12% of liquid water volume is inhabited by life

Abstract

Based on a pressure-temperature (P-T) phase diagram model of the Earth, Jones & Lineweaver (2010) described uninhabited terrestrial liquid water. Our model represents the atmosphere, surface, oceans and interior of the Earth - allowing the range of P-T conditions in terrestrial environments to be compared to the phase regime of liquid water. Here we present an overview and additional results from the Earth model on the location of the deepest liquid water on Earth and the maximum possible extent of the terrestrial biosphere. The intersection of liquid water and terrestrial phase space indicates that the deepest liquid water environments in the lithosphere occur at a depth of ~ 75 km. 3.5 % of the volume of the Earth is above 75 km depth. Considering the 3.5 % of the volume of the Earth where liquid water exists, ~ 12% of this volume is inhabited by life while the remaining ~ 88% is uninhabited. This is distinct from the fraction of the volume of liquid water occupied by life. We find that at least 1% of the volume of liquid water on Earth is uninhabited. Better geothermal gradients in the Earth's crust and mantle will improve the precision and accuracy of these preliminary results.