Earth and Planetary Sciences ETDs

Publication Date

Winter 11-20-2020

Abstract

Boron has been detected on Mars [Gasda et al., 2017, Das et al., 2019, 2020] within calciumsulfate veins found within clay-rich rocks on Mars by the Mars Science Laboratory (MSL) rover using Laser Induced Breakdown Spectroscopy (LIBS) analysis. Boron plays a vital role in stabilizing ribose on Earth and has been suggested as a key requirement for life [Scorei et al., 2006, 2012; Furukawa et al., 2013, 2017; Becker et al., 2019]. Additionally, boron readily adsorbs to phyllosilicate clay minerals and is often associated with biologic processes in clay soils. The discovery of boron on Mars in proximity to phyllosilicate bedrock may have strong implications for potential past prebiotic conditions on Mars. This study generates a suite of clays with sorbed boron, including both typical terrestrial clays as well as Mars-analog clays, to understand the controls on boron adsorption and to examine these clay materials with LIBS in an effort to develop standards for future analyses on Mars. These standards can also help to better understand past analyses where boron has been detected. Geochemical and XRD characterization of the suite of clays was also conducted, including a clay collected from boron deposits of the western United States. Characterization analysis determined the baseline chemistry of the clays prior to adsorption and also revealed the purity of the clays. The samples of clays, while predominantly consisting of the expected Fe/Mg phyllosilicate typical of Mars, also contain minor and trace amounts of other minerals. These samples may therefore better represent the impure clay-bearing rocks on Mars. Adsorption analysis revealed that the montmorillonite clays were able to adsorb a significant amount of boron, which was greater than seen in previous literature, although this study attributes this to different experimental conditions. Analysis also determined that there is a positive correlation between concentration of boron in the fluid and final adsorbed concentration of boron on the clay. Experiments concerning the time factor indicated that adsorption happens quickly as v extended exposure to borate fluid did not increase boron adsorption. Further studies will adsorb boron to selected clays at varying pH conditions to analyze the ideal conditions for boron sorption and compare which clay types adsorb boron most effectively. The results of this study provides insight into boron sorption onto Mars-analog clays. Boron-rich clays were created that can be exposed to ribose for organic analysis in follow-up studies. A series of boron-enriched standards were also created that can be used by the MSL and future Mars 2020 rovers. The results of this study may also provide insight into Martian groundwater geochemistry processes and the problems concerning the apparent lack of Martian evaporite deposits.

Degree Name

Earth and Planetary Sciences

Level of Degree

Masters

Department Name

Department of Earth and Planetary Sciences

First Committee Member (Chair)

Laura Crossey

Second Committee Member

Patrick Gasda

Third Committee Member

Horton Newsom

Fourth Committee Member

Adrian Brearley

Language

English

Keywords

Mars, geochemistry, Curiosity, adsorption, clays, ChemCam

Document Type

Thesis

Download

Share

COinS