Date of Graduation

7-2020

Document Type

Thesis

Degree Name

Master of Science in Geology (MS)

Degree Level

Graduate

Department

Geosciences

Advisor/Mentor

Adriana Potra

Committee Member

Vincent Chevrier

Second Committee Member

Barry Shaulis

Third Committee Member

Philip Hays

Keywords

carbonaceous, chondrites, ordinary, rare earth elements, sulfur, weathering

Abstract

Understanding the effects of weathering of chondrites is essential to gaining accurate and useful information about the formation of our solar system, as well as a more detailed account of the mobilization of chondritic compounds when they encounter terrestrial conditions. Elemental concentrations and stable isotope analyses of chondrites, considered to be the most primordial material in the solar system, are two tools which help unlock the weathering patterns of these specimens when they enter the earth system. However, it is not currently known exactly how time spent in the field alters rare earth element (REE) concentration or δ34S signatures within carbonaceous and ordinary chondrites. This study shows that REE concentration is an ineffective way to determine residence time. There are no meaningful trends identified throughout the exhaustive display of the REE results. However, the current data suggest entry to the earth system fractionates sulfur within chondrites and produces variable δ34S. The main result of the sulfur study shows chondrite falls are not fractionated with respect to δ34S with a tight range of results which span from -0.32‰ to 1.74‰, while chondrite finds contain a wide variety of δ34S signatures ranging from -0.5‰ to 5.45‰. This finding suggests the longer amount of time spent within the earth system will fractionate the sulfur species considerably within chondritic material due to exposure to aqueous fluids, temperature fluctuations, and microbiotic interaction. A better understanding of the relationship between residence time and δ34S values may enable stable isotopic analyses of sulfur to be used to support ongoing efforts to gain more insights into the behavior and fate of chondrites upon interaction with the earth system.

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