ASU Electronic Theses and Dissertations
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The present understanding of the formation and evolution of the earliest bodies in the Solar System is based in large part on geochemical and isotopic evidences contained within meteorites. The differentiated meteorites (meteorites originating from bodies that have experienced partial to complete melting) are particularly useful for deciphering magmatic processes occurring in the early Solar System. A rare group of differentiated meteorites, the angrites, are uniquely suited for such work. The angrites have ancient crystallization ages, lack secondary processing, and have been minimally affected by shock metamorphism, thus allowing them to retain their initial geochemical and isotopic characteristics at the …
- Sanborn, Matthew Edward, Wadhwa, Meenakshi, Hervig, Richard, et al.
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Variations of 238U/235U in sedimentary carbonate rocks are being explored as a tool for reconstructing oceanic anoxia through time. However, the fidelity of this novel paleoredox proxy relies on characterization of uranium isotope geochemistry via laboratory experimental studies and field work in modern analog environmental settings. This dissertation systematically examines the fidelity of 238U/235U in sedimentary carbonate rocks as a paleoredox proxy focusing on the following issues: (1) U isotope fractionation during U incorporation into primary abiotic and biogenic calcium carbonates; (2) diagenetic effects on U isotope fractionation in modern shallow-water carbonate sediments; (3) the effects of anoxic depositional environments …
- Chen, Xinming, Anbar, Ariel D, Williams, Lynda B, et al.
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