Isotope systematics of the eucrite Jonzac: A look into the history of the eucrite parent body using the Lu-Hf, Sm-Nd, Pb-Pb, & U-Pb isotopic systems
| dc.contributor.advisor | Lapen, Thomas J. | |
| dc.contributor.committeeMember | Andreasen, Rasmus | |
| dc.contributor.committeeMember | Brandon, Alan D. | |
| dc.contributor.committeeMember | Righter, Kevin | |
| dc.creator | Dietderich, Jesse 1980- | |
| dc.date.accessioned | 2014-12-09T13:40:17Z | |
| dc.date.available | 2014-12-09T13:40:17Z | |
| dc.date.created | December 2012 | |
| dc.date.issued | 2012-12 | |
| dc.date.updated | 2014-12-09T13:40:17Z | |
| dc.description.abstract | The main objective of this research is to understand the history of the eucrite parent body through the isotopic and petrologic study of the monomict eucrite Jonzac. Jonzac is a type 7 eucrite defined by less prominent Ca-zoning than that of type 4 eucrites and that it contains partly inverted pigeonite, which is a type 6 feature. The metamorphic textures observed include aggregates of polygonal pyroxene, jagged-shaped plagioclase, and recrystallization of the clastic matrix. Four isotopic systems (Lu-Hf, Sm-Nd, Pb-Pb, and U-Pb) were used to determine ages reflecting igneous formation and subsequent thermal and impact metamorphism of this meteorite. The igneous crystallization age is 4.546 ± 0.050 Ga (2σ) defined by U-Pb in zircon which we interpret as being the least prone to thermal disturbances. The other ages are either much younger or show signs of disturbances. A 4-point Lu-Hf isochron of age 4.236 ± 0.026 Ga (2σ; MSWD = 2.4) and a step-leaching 3-point Pb-Pb inverse isochron age of 4.352 ± 0.018 Ga (2σ; MSWD = 436) are much younger than the generally accepted formation interval for non-cumulate eucrites. A 4-point Sm-Nd isochron produced an ‘age’ of 4.733 ± 0.087 Ga (2σ; MSWD = 0.38). The discordant set of isochron ages indicate decoupling between isotope systems and support the hypothesis that the Lu-Hf, step-leaching Pb-Pb, and Sm-Nd isotope systems are disturbed. The ages likely reflect disturbances related to recrystallization during a period(s) of thermal metamorphism likely related to impact processes. The Lu-Hf and step leaching Pb-Pb ages place constraints on the timing of impact processes on the HED parent body and these ages are substantially older than the generally accepted period of late-heavy-bombardment (4.1 – 3.8 Ga) inferred from lunar studies. | |
| dc.description.department | Earth and Atmospheric Sciences, Department of | |
| dc.format.digitalOrigin | born digital | |
| dc.format.mimetype | application/pdf | |
| dc.identifier.uri | http://hdl.handle.net/10657/802 | |
| dc.language.iso | eng | |
| dc.rights | The author of this work is the copyright owner. UH Libraries and the Texas Digital Library have their permission to store and provide access to this work. Further transmission, reproduction, or presentation of this work is prohibited except with permission of the author(s). | |
| dc.subject | Eucrite | |
| dc.subject | Jonzac | |
| dc.subject | Vesta | |
| dc.subject | Isotopes | |
| dc.subject | Age | |
| dc.subject.lcsh | Geology | |
| dc.title | Isotope systematics of the eucrite Jonzac: A look into the history of the eucrite parent body using the Lu-Hf, Sm-Nd, Pb-Pb, & U-Pb isotopic systems | |
| dc.type.dcmi | Text | |
| dc.type.genre | Thesis | |
| thesis.degree.college | College of Natural Sciences and Mathematics | |
| thesis.degree.department | Earth and Atmospheric Sciences, Department of | |
| thesis.degree.discipline | Geology | |
| thesis.degree.grantor | University of Houston | |
| thesis.degree.level | Masters | |
| thesis.degree.name | Master of Science |