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Full-Text Articles in Physical Sciences and Mathematics
Nature And Origin Of Fissure Ore At The Porphyry-Epithermal Transition Zone Of The Bingham Canyon Porphyry Cu-Au-Mo Deposit, Utah, David Harris Tomlinson
Nature And Origin Of Fissure Ore At The Porphyry-Epithermal Transition Zone Of The Bingham Canyon Porphyry Cu-Au-Mo Deposit, Utah, David Harris Tomlinson
Theses and Dissertations
Late-stage fissure-filling ore at the world class Bingham Canyon, Utah, porphyry copper deposit has long been recognized, but poorly studied. Physical and chemical characterization of the Pb-Zn-Cu-Ag-Au mineralized fissures in the porphyry-epithermal transition zone provides insight into the origin, timing, and controls of ore deposition. These sheared sulfide-rich fissures are dominated by pyrite and multiple generations of quartz, with lesser amounts of other sulfides and gangue minerals. Au (0.27 to 4.61 ppm) provides the most value to the ore in the transition zone. Host rocks include Eocene monzonite and Paleozoic limestone and quartzite"”all of which can contain economic ore bodies. …
Formation Of Rapakivi Feldspars In The Deer Isle Granite Complex, Coastal Maine: In Situ Lead Isotope And Trace Element Analysis, William Desmond Obrien
Formation Of Rapakivi Feldspars In The Deer Isle Granite Complex, Coastal Maine: In Situ Lead Isotope And Trace Element Analysis, William Desmond Obrien
Theses and Dissertations
Rapakivi and alkali feldspar phenocrysts from the Deer Isle Granite Complex were investigated using in situ trace element and Pb isotope geochemistry to see if magma mixing or isothermal decompression was responsible for their formation. Pb isotope and trace element profiles, along with CL imagery of quartz phenocrysts, indicate compositional changes in the magma chamber occurred during rapakivi and alkali feldspar growth. Repeated episodes of magma mixing/replenishment by relatively isotopically primitive and LREE enriched magmas (along with hybridized variations with the host magma) created localized disequilibration. Alkali feldspar phenocrysts proximal to these zones of thermal perturbation were first resorbed and …
Dinosaurian Faunas Of The Cedar Mountain Formation And La-Icp-Ms Detrital Zircon Ages For Three Stratigraphic Sections, Hirotsugu Mori
Dinosaurian Faunas Of The Cedar Mountain Formation And La-Icp-Ms Detrital Zircon Ages For Three Stratigraphic Sections, Hirotsugu Mori
Theses and Dissertations
The Cedar Mountain Formation contains the most diverse record of Early Cretaceous dinosaurs in the western hemisphere. However, analyses of its faunas have been hindered because 1) most taxa are based on incomplete/fragmentary materials or incomplete descriptions, 2) most sites and some horizons preserve few taxa, and 3) the stratigraphy and geochronology are poorly understood. To help resolve these stratigraphic and correlation problems U-Pb LA-ICP-MS detrital zircon ages were obtained at significant sites and horizons. These dates indicate all sites at or near the base of the formation are no older than 122 to 124 Ma, thus all basal stratigraphic …
A Microanalytical Approach To Understanding The Origin Of Cumulate Xenoliths From Mauna Kea, Hawaii, Megan Pickard
A Microanalytical Approach To Understanding The Origin Of Cumulate Xenoliths From Mauna Kea, Hawaii, Megan Pickard
Theses and Dissertations
Cumulate xenoliths erupted with alkalic hawaiite lavas from a postshield cinder cone on Mauna Kea, Hawaii include a variety of mafic and ultramafic rock types. Previous studies of major and trace element compositions of minerals in the xenoliths are interpreted to show transitional to alkalic magma parentages from the postshield stage, although any orthopyroxene-bearing xenoliths are considered to have tholeiitic parents. Major element compositions minerals were analyzed using the electron microprobe and trace element compositions of clinopyroxene grains were analyzed by laser ablation inductively coupled plasma mass spectrometry. In this study, major element compositions of clinopyroxene, olivine and plagioclase grains …