Earth and Planetary Sciences ETDs

Publication Date

Summer 7-1-2017

Abstract

The oxygen isotope composition of water extracted from Martian meteorites appears not to be in isotopic equilibrium with the silicate portion of the meteorites. This disequilibrium suggests the existence of multiple distinct oxygen isotope reservoirs on planet Mars. Here we present oxygen isotope measurements of waters extracted from Martian shergottites Tissint, Zagami and NWA-7042 and from nakhlite NWA-10153. These waters were extracted by stepwise heating to preserve segregation between low temperature adsorbed waters, intermediate temperature mineral waters and the high temperature mineral structural OH groups. The results of our study, analyzed cooperatively with previous work by Karlsson et al., (1992) and Agee et al., (2013), show that two isotopically distinct water reservoirs exist on Mars. The isotopic influence of these two reservoirs is preserved in two distinct groups of Martian meteorites. Martian shergottites preserve the isotopic composition of Martian mantle waters while nakhlites and Chassigny preserve a contribution from a reservoir elevated in 17O. The presence of low temperature aqueous alteration minerals in nakhlites and Chassigny suggests that the elevated 17O component is sourced from Martian near-surface waters. Based on oxygen isotope measurements of 17O enriched waters extracted from Martian meteorites we propose that the Martian near-surface waters must have a Δ’17O of at least 0.89‰ or greater.

Degree Name

Earth and Planetary Sciences

Level of Degree

Masters

Department Name

Department of Earth and Planetary Sciences

First Committee Member (Chair)

Karen Ziegler

Second Committee Member

Zachary Sharp

Third Committee Member

Carl Agee

Language

English

Keywords

High precision triple oxygen terrestrial water standards VSMOW and SLAP, Δ17O oxygen isotope composition, Isotopic composition of Martian water, Evolution of water on Mars, History of water on planet Mars, Isotopically distinct water reservoirs on Mars, Isotopic fractionation of water in Martian atmosphere.

Document Type

Thesis

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