Effects of basalt composition on a martian analogue magma-sediment hydrothermal system studied through thermochemical modeling

Cogliati, Simone; Crandall, Jake; Filiberto, Justin and Schwenzer, Susanne (2022). Effects of basalt composition on a martian analogue magma-sediment hydrothermal system studied through thermochemical modeling. In: Lunar and Planetary Science Conference 2022, 7-11 Mar 2022, Houston.

Abstract

Introduction: High-temperature hydrothermal systems have been identified on Mars associated with both hypervelocity impacts and magmatic activity on Mars’s early history [1, 2]. These processes may have produced habitable environments by providing heat, energy, and volatile species necessary to support microbial life [3, 4]. Hydrothermal systems formed after the intrusion of mafic magmas in sedimentary rocks are of particular interest when investigating the habitability of high-temperature aqueous environments on Mars [5, 6], because during magma-sediment contact metamorphism bond fluids (e.g. in ice, pore spaces, minerals) are mobilized favoring the alteration of the country rocks and the release of bio-essential elements [7, 8]. The chemistry and mineralogy of these systems on Mars are not well constrained and, for this reason, terrestrial analogues need to be investigated. Costello et al. [5] and Crandall et al. [6] have studied a mafic dike intruding the Jurassic Entrada sandstone (Colorado Plateau, UT). The intrusion has produced a hydrothermal system with Cl-CO2 rich fluids and near-neutral pH, which induced chemical and mineralogical changes in the dike and in the sediments [5, 6]. The system reached temperatures higher than 700 °C around the contact zone [6], but lower temperatures (< 200 °C) were reached as the system cooled down [5] making the environment potentially habitable [6]. However, previous studies do not consider compositional differences between the terrestrial dike and basaltic rocks on Mars [9, 10] making difficult a direct comparison between alteration mineralogy and brine chemistry of terrestrial and martian systems. Here, we use thermochemical modelling to investigate how differences in bulk dike composition will affect secondary mineral assemblages and fluid chemistry.

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