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The Formation History Of Layered Chondrules In Acfer-139 (Cr2), Matt Downen

Mahurin Honors College Capstone Experience/Thesis Projects

Chondrules are spherical grains made of silicates and metal that represent some of the oldest materials our solar system. Acfer-139 (CR) is a carbonaceous chondrite with large multilayered chondrules. The multilayered chondrules are composed of a silicate core surrounded by alternating layers of silicates and metals. Serial sectioning was used to analyze the sample in three dimensions. EMPA and LA-ICP-MS were used to create elemental maps of Acfer-139 (CR2) and determine the geochemistry of different layers in each thick section cut. XRCMT was used to construct a 3-D model of a large multilayered chondrule named Ch-1 with concentric layers of …

Trace Element Analysis Of Rutile And Zr-In-Rutile Thermometry For Southern Appalachian Pelitic Schists, Kathryn A. Eccles

Honors Program Projects

Over the past decade, geochronology studies in the southern Appalachians have focused on zircon, monazite, and mica ages to confirm the occurrence of a major Taconic event (~460‐450 Ma) affecting the Western and Central Blue Ridge, followed by a younger NeoAcadian (~360‐345 Ma) event affecting the Eastern Blue Ridge and Piedmont. Peak conditions of granulite facies metamorphism are estimated at ~850°C (garnet‐biotite) and 7‐9 kbar (GASP) for sillimanite schists at Winding Stair Gap (WSG), but thermobarometric studies of metasedimentary rocks in the region are limited and consequently Pressure‐Temperature‐time‐Deformation (P‐T‐t‐D) paths are poorly understood. Many details of the orogenic processes in …

U-Th-Ba Elemental Fractionation During Partial Melting Of Crustal Xenoliths And Its Implications For U-Series Disequilibria In Continental Arc Rocks, Raul Brens Jr.

FIU Electronic Theses and Dissertations

Understanding U-series isotopic disequilibria of partially melted crust is integral for determining the effect that crustal assimilation has on the U-series signature of magmas. In this work, U, Th and Ba (as a proxy for Ra) elemental abundances were gathered on the quenched glass in partially melted crustal xenoliths of granitic composition using microbeam techniques. The crustal xenoliths, which are found in basaltic lava, from Mirador Volcano in Chile, are old, and can be assumed to be at secular equilibrium, whereas melting occurred during eruption of Mirador in 1979. A comparison of the ratios Ba/Th and U/Th in the partial …

Dietary Ecology Of The Endangered Grevy's Zebra, Equus Grevyi, In Historic And Modern Laikipia, Susan Olszewski

Summer Research

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The Grevy’s zebra, a highly endangered equid, has undergone the most dramatic reduction in population of any African mammal. The cause of this decline is largely unknown. Over the last 100 years, Kenya has undergone many changes in land use practice and policy that have lead to high densities of people and livestock in close proximity to wildlife. Recent studies suggest these increases in human population and livestock pressure in overgrazed areas have negatively shifted the diet of this the Grevy’s zebra. Using stable isotope analysis, this study proposes to create a dietary timeline …

Geochemistry Of The Mt. Persis Volcanics And Evidence For Thickening Of Cascade Crust Over Time, Monica Hanson

Summer Research

The Cascade Range is a classic example of a continental magmatic arc, a belt of igneous activity resulting from subduction of the oceanic Juan de Fuca plate beneath the western margin of the North American plate. The Cascade arc, which started forming about 38 million years ago, is unique in that extensive uplift and erosion have exposed plutonic and volcanic rocks of similar age. This study will focus on the Mt. Persis area in the North Cascades, where a pluton of the Index batholith is surrounded by near-source volcanic rocks and suggests that the volcano may have originated from the …