Constraining the Extent of Groundwater Alteration of Martian Sedimentary Deposits: An Investigation of Mg-sulfate Formation Mechanisms

Abstract:

Understanding the groundwater history of Mars is paramount in constraining the planet’s surface processes and aids in evaluating potentially habitable environments. Evidence of post-depositional alteration of sedimentary rocks can provide a snapshot of the chemical and physical characteristics of the aqueous solutions that have moved through the strata. Due to their high solubility, Mg-sulfates are exceptionally sensitive to the presence of water; thus, their presence likely serves as a constraint on the latest groundwater alteration within a sedimentary unit. In order to determine the timing of Mg-sulfate deposition, as well as the degree of diagenetic groundwater alteration, the mineralogy, sedimentary fabric, and depositional structures of the deposits must be characterized.

The scope of this project includes the classification of Mg-sulfate deposits observed by the Spirit, Opportunity, and Curiosity rover missions with a focus on determining the formation mechanisms and depositional environments of the observable features. Mg-sulfate data in the literature is aggregated and sorted by qualitative traits (i.e., dominant lithology, associated sedimentary structures, mineralogy, appearance in bedding) and quantitative analysis (i.e., chemical composition, unit proportion, spatial and stratigraphic extent). In addition to compiling data from Mars, terrestrial analogs presenting in-situ Mg-sulfates are investigated to help constrain possible formation conditions and hydrologic system characteristics. We aim to provide insight into several outstanding uncertainties surrounding the presence of Mg-sulfates within Martian sediments, including their origin as either primary or secondary features, as well as their use in discerning the differences between multiple episodes of aqueous alteration or differentiating evolving alteration fluids.