Properties of the Nili Fossae Olivine-clay-carbonate lithology: orbital and in situ at S\'e\'itah

TL;DR

This study combines orbital and in situ data to analyze the properties and origin of the olivine-clay-carbonate lithology at Sétah in Jezero crater, suggesting a flood lava origin with limited post-emplacement alteration.

Contribution

It provides new insights into the composition, grain size, and viscosity of the lithology, and proposes a flood lava origin based on combined orbital and rover data, including a new CRISM map.

Findings

Clay consistent with talc or serpentine from in situ data

Low viscosity suggests flood lava origin

Limited post-emplacement alteration observed

Abstract

We examine the observed properties of the Nili Fossae olivine-clay-carbonate lithology from orbital data and in situ by the Mars 2020 rover at the S\'e\'itah unit in Jezero crater, including: 1) composition (Liu, 2022) 2) grain size (Tice, 2022) 3) inferred viscosity (calculated based on geochemistry collected by SuperCam (Wiens, 2022)). Based on the low viscosity and distribution of the unit we postulate a flood lava origin for the olivine-clay-carbonate at S\'e\'itah. We include a new CRISM map of the clay 2.38 {\mu}m band and use in situ data to show that the clay in the olivine cumulate in the S\'e\'itah formation is consistent with talc or serpentine from Mars 2020 SuperCam LIBS and VISIR and MastCam-Z observations. We discuss two intertwining aspects of the history of the lithology: 1) the emplacement and properties of the cumulate layer within a lava lake, based on terrestrial analogs in the Pilbara, Western Australia, and using previously published models of flood lavas and lava lakes, and 2) the limited extent of post emplacement alteration, including clay and carbonate alteration (Clave, 2022; Mandon, 2022).