Thermophysical assessment on the feasibility of basal melting in the south polar region of Mars

TL;DR

This study uses thermophysical modeling to evaluate the likelihood of basal melting and subglacial lakes in Mars's south polar layered deposits, finding such features are improbable under typical conditions.

Contribution

It provides a comprehensive thermophysical analysis showing subglacial lakes are unlikely in Mars's south pole due to low heat flow and specific ice composition requirements.

Findings

Subglacial lakes are unlikely unless the ice contains >60% dust.

Thick layers of dirty ice could enable basal melting.

Recent magmatic intrusions are an improbable cause for lakes.

Abstract

Bright basal reflectors in radargram from the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) of the Martian south polar layered deposits (SPLD) have been interpreted to be evidence of subglacial lakes. However, this interpretation is difficult to reconcile with the low Martian geothermal heat flow and the frigid surface temperature at the south pole. We conduct a comprehensive thermophysical evolution modeling of the SPLD and show that subglacial lakes may only form under exceptional circumstances. Subglacial lakes may form if the SPLD contains more than 60 % dust volumetrically or extremely porous ice (>30 %), which is unlikely. A thick (>100 m) layer of dirty ice (>90% dust) at the base of the SPLD may also enable basal melting, resembling a sludge instead of a lake. Other scenarios enabling subglacial lakes in the SPLD are equally unlikely, such as recent magmatic intrusions at shallow depths.