Tharsis-sourced relatively dust-free lavas and their possible relationship to Martian meteorites

Abstract

The launch sites for Martian (SNC) meteorites remain unknown, but they must derive from young volcanic provinces. We present the first geologic and spectroscopic characteristics of a suite of relatively dust-free lava flows that extend from underneath the regional dust cover on the south flank of the Tharsis volcanic province on Mars. The purpose of this work is to (1) characterize these flows geologically by using THermal EMission Imaging System (THEMIS) data supplemented by Mars Orbital Laser Altimeter (MOLA), Mars Orbital Camera (MOC), and High Resolution Imaging Science Experiment (HiRISE) datasets and (2) use Thermal Emission Spectrometer (TES) data in order to test the hypothesis that Tharsis represents a source for the SNCs. These flows are morphologically similar to flood lavas in Amazonis Planitia with the flow surfaces being a complex mixture of surficial materials with limited exposure. The spectrally derived mineral composition and geochemistry for three flows, reveals basaltic compositions that have an affinity with SNCs, especially the basaltic shergottites. However, discrepancies between spectra and mineral percentages for the flows versus the shergottites, together with the observation of surface deposits on the flow surfaces, make any connection between these flows and the SNCs tenuous, although not impossible. Further testing of a Tharsis–SNC relationship will require measurements at finer spatial resolutions, perhaps even in-situ.