Geology Theses and Dissertations

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Browsing Geology Theses and Dissertations by Author "Archer, Gregory Jude"

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    Highly Siderophile Elements and the Rhenium-Osmium System in Chondritic Components
    (2012) Archer, Gregory Jude; Walker, Richard J; Geology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Chondritic meteorites and their components provide information about the early solar system, as well as processes that affected meteorite parent bodies post-accretion. The rare earth element (REE) abundances, highly siderophile element (HSE) abundances, Re-Os isotope systematics, Re isotopic composition, and Os isotopic composition were investigated in Allende chondritic components in order to: (1) classify several recently separated Allende calcium-aluminum-rich inclusions (CAIs) based on REE abundance patterns, (2) determine the abundances of six HSE (Re, Os, Ir, Ru, Pt, and Pd) in CAIs, chondrules, and matrix, and compare the different chondritic components, (3) further assess the magnitude and characteristics of open-system behavior on the Allende parent body using Re-Os of CAIs, chondrules, and matrix, (4) determine if the Re isotopic composition of CAIs was altered by cosmic ray interactions, and (5) investigate possible nucleosynthetic anomalies in CAIs.
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    Highly Siderophile Elements, 187Re-187Os and 182Hf-182W Isotopic Systematics of Early Solar System Materials: Constraining the Early Evolution of Chondritic and Achondritic Parent Bodies
    (2016) Archer, Gregory Jude; Walker, Richard J; Geology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Highly siderophile element (HSE) abundances and 187Re-187Os isotopic systematics for H chondrites and ungrouped achondrites, as well as 182Hf-182W isotopic systematics of H and CR chondrites are reported. Achondrite fractions with higher HSE abundances show little disturbance of 187Re-187Os isotopic systematics. By contrast, isotopic systematics for lower abundance fractions are consistent with minor Re mobilization. For magnetically separated H chondrite fractions, the magnitudes of disturbance for the 187Re-187Os isotopic system follow the trend coarse-metal