Amagmatic hydrothermal systems on Mars from radiogenic heat

Abstract

Long-lived hydrothermal systems are prime targets for astrobiological exploration on Mars. Unlike magmatic or impact settings, radiogenic hydrothermal systems can survive for >100 million years because of the Ga half-lives of key radioactive elements (e.g., U, Th, and K), but remain unknown on Mars. Here, we use geochemistry, gravity, topography data, and numerical models to find potential radiogenic hydrothermal systems on Mars. We show that the Eridania region, which once contained a vast inland sea, possibly exceeding the combined volume of all other Martian surface water, could have readily hosted a radiogenic hydrothermal system. Thus, radiogenic hydrothermalism in Eridania could have sustained clement conditions for life far longer than most other habitable sites on Mars. Water radiolysis by radiogenic heat could have produced H2, a key electron donor for microbial life. Furthermore, hydrothermal circulation may help explain the region’s high crustal magnetic field and gravity anomaly.

Early crustal processes revealed by the ejection site of the oldest martian meteorite

“…The geological stability of this region makes it unlikely that Amazonian and Hesperian hydrothermal processes have contributed to forming magnetite to be the dominant magnetization carrier in this highly magnetized region of the martian crust 42,43 . Instead, analysis of magnetic signatures, K and Th enrichment, and depth of large impact craters in Eridania basins within the TCTS region suggest non-magmatic long-lived hydrothermal systems, heat-driven by radiogenic elements with half-lives of billions of years 44 (e.g., 232 U and 40 K), that might have significantly contributed to the observed crustal magnetic field throughout the pre-Noachian and Noachian eras [42][43][44] . Early hydrothermal circulation in this province would potentially have sustained life-compatible environment for a long period of time 3,44 .…”

Time-Sensitive Aspects of Mars Sample Return (MSR) Science

“…Since the first discovery and in situ analyses 17 years ago of ancient sedimentary rocks on Mars (Squyres et al, 2004), a wealth of data has been returned from orbital and landed missions that support increasingly detailed comparisons between terrestrial and martian sedimentary records of planetary habitability and biosignature preservation potential (Grotzinger et al, 2014, Hurowitz et al, 2017, McLennan et al, 2019. At the same time, current understanding of the diversity and dynamics of igneous and hydrothermal environments has deepened over the last several years (e.g., Udry et al, 2020;Ojha et al, 2021), along with new constraints on planetary-scale structure and dynamics (e.g., Costa et al, 2020), and on volatile budgets and their exchange between the martian interior and atmosphere (e.g., Wade et al, 2017;Scheller et al, 2021;Wordsworth et al, 2021). The Perseverance Rover will leverage this understanding to collect and cache samples from one of the most geologically diverse settings on the martian surface in a critical next step in the planned Mars Sample Return (MSR) campaign (Beaty et al, 2019;Farley et al, 2020).…”

Consolidated Chemical Provinces on Mars: Implications for Geologic Interpretations

“…Furthermore, chemical maps are generated at a resolution of 5° × 5° due to broad footprint of the GRS instrument (Boynton et al, 2007). We use the latest refined datasets of GRS, including Al and S used in the literature (cf., Hood et al, 2016Hood et al, , 2019Ojha et al, 2018Ojha et al, , 2021, and compare them with GRS data used a decade ago (Boynton et al, 2007;Gasnault et al, 2010;Karunatillake et al, 2009;Taylor et al, 2010), including the archived data at the NASA Planetary Database System (PDS) (https://pds-geosciences.wustl.edu/ody/ody-m-grs-5-elements%20v1/ odgm_xxxx/data/smoothed/). The delineation of provinces also mitigates the substantial spatial autocorrelation inherent in the GRS data by associating large chemical deviations with multi-pixel regions rather which are larger than the GRS instrument footprint (Karunatillake et al, 2009).…”