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Showing 1 to 17 of 17 for “"Uranium series"”.
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Uranium-series radionuclide records of paleoceanographic and sedimentary changes in the Arctic Ocean
The radionuclides 231Pa and 230Th, produced in the water column and removed from the ocean by particle scavenging and burial in sediments, offer a means for paleoceanographers to examine past dynamics of both water column and sedimentary processes. I show for the first time that a state of balance …
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Uranium-series radionuclide records of paleoceanographic and sedimentary changes in the Arctic Ocean
The radionuclides ²³¹Pa and ²³⁰Th, produced in the water column and removed from the ocean by particle scavenging and burial in sediments, offer a means for paleoceanographers to examine past dynamics of both water column and sedimentary processes. I show for the first time that a state of balance …
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Uranium-series isotope constraints on magma generation and differentiation in the central Oregon Cascades
… central Oregon Cascades through application of uranium-series (U-series) isotope data, in conjunction with elemental and Sr-Nd isotope data. Trace element and isotopic (87Sr/86Sr, 143Nd/144Nd) data for the most primitive lavas suggest derivation by < 10% partial melting of a garnet-bearing …
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Studies of Magmatism by Trace Element Partitioning Between Clinopyroxene and Silicate Melt, Uranium-Series Disequilibria in Lavas From Subduction Zones, and Non-Traditional Stable Isotopes
Finally, in chapter 5, I report results of Fe-Mg isotopic analyses of a thermal migration experiment. Significant mass-dependent Fe-Mg isotopic fractionations occur in the melt-present portion of the experiment. I conclude that the positive co-variation of Fe-Mg isotopes could be an important …
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Uranium-series geochronology and stable isotope analysis of travertine from Soda Dam, New Mexico : a Quaternary record of episodic spring discharge and rivern incision in the Jemez Mountains hydrothermal system
High precision uranium-series (U-series) geochronology provides data on timing of travertine deposition at Soda Dam, and a paleohydrologic record for the Valles Caldera hydrothermal system in Northern New Mexico for at least the last 500 ka. Travertine-depositing springs occur in San Diego Canyon, …
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Use of uranium decay series for dating an archaeological smelting site
… an assessment of the applicability of uranium decay series dating to El Manchon slags was made. El Manchon is the only Mesoamerican site to exhibit smelting technology. Uranium series dating is typically used on geologically old natural material, but the El Manchon slags were not …
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Constraining circulation changes through the last deglaciation with deep-sea coral radiocarbon and sedimentary 231Pa/230Th
… of ocean processes. Here I use radiocarbon and uranium series isotopes to investigate the ocean’s role in climate change over the last deglaciation. I present a new method for rapid radiocarbon analyses as a means of age-screening deep-sea corals for further study. Based on age survey results, I …
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Constraining circulation changes through the last deglaciation with deep-sea coral radiocarbon and sedimentary ²³¹Pa/²³⁰Th
… of ocean processes. Here I use radiocarbon and uranium series isotopes to investigate the ocean's role in climate change over the last deglaciation. I present a new method for rapid radiocarbon analyses as a means of age-screening deep-sea corals for further study. Based on age survey results, I …
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Palaeoenvironmental and palaeogeographic reconstruction of the Tequixquiac Basin, Central Eastern Mexico: Mid to late Pleistocene environments
… LOI, AMS radiocarbon, 40Ar/39Ar and Uranium-series dating has allowed a chronologically constrained paleoenvironmental and palaeogeographic reconstruction of the study area. The results of the study suggest that the Tequixquiac Basin has undergone a significant hydrological change …
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Basalt petrogenesis beneath slow- and ultraslow-spreading Arctic mid-ocean ridges
… experimental results to model time-dependent uranium-series isotopes do not support the presence of a fixed quantity of garnet pyroxenite in the source of OIB. To use U-series isotopes to further constrain mantle heterogeneity and the timing and nature of melting and melt transport processes, …
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Basalt petrogenesis beneath slow- and ultraslow-spreading Arctic mid-ocean ridges
… experimental results to model time-dependent uranium-series isotopes do not support the presence of a fixed quantity of garnet pyroxenite in the source of OIB. To use U-series isotopes to further constrain mantle heterogeneity and the timing and nature of melting and melt transport processes, …
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GEOCHEMISTRY AND PETROGRAPHY OF SPELEOTHEMS FROM TURKEY AND IRAN: PALAEOCLIMATE AND DIAGENESIS
… and petrographic proxies, and precisely dated by Uranium Series dating. As U/Th dating is only viable for samples up to approximately 700 kyr of age, U/Pb dating must be used to date older samples. In this study, U/Pb methods were used to date an aragonite layer in a speleothem from Iran, …
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Quaternary glaciation in the Pindus Mountains, Northwest Greece
… sedimentological analysis, soil analysis and Uranium-series dating. Four glacial events are recorded in the sedimentological and geomorphological records. The more extensive recorded glaciation pre-dates 350,000 years BP and was characterised by extensive valley glaciers and ice-fields. A …
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Speleothem Palaeoclimatology in the Maya Lowlands of Northwestern Yucatán, Mexico
… the Terminal Classic. Using lamina counting and uranium series disequilibrium dating on the stalagmite Tzab06-1, I reconstruct the precise duration, timing, and relative severity of wet season droughts in the Terminal Classic. This is the first proxy record from the northern Yucatán resolved on …
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Temporal and petrogenetic constraints on volcanic accretionary processes at 9-10 degrees north East Pacific Rise
… and timing of volcanic and magmatic activity. Uranium series nuclides are susceptible to fractionation by magmatic processes that occur beneath mid-ocean ridges, and the half-lives of 226Ra (1.6 kyrs) and 230Th (75 kyrs) make them ideally suited for determining eruption ages and placing …
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Temporal and petrogenetic constraints on volcanic accretionary processes at 9-10 degrees North East Pacific Rise
… and timing of volcanic and magmatic activity. Uranium series nuclides are susceptible to fractionation by magmatic processes that occur beneath mid-ocean ridges, and the half-lives of 22 6Ra (1.6 kyrs) and 23Th (75 kyrs) make them ideally suited for determining eruption ages and placing …
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Geochemical records in travertine veins at the Green River CO2 seeps (Utah)
Geological Carbon Storage is necessary for reduction of anthropogenic carbon dioxide (CO2) emissions. CO2 is captured at 'point sources' (i.e. heavy industries, where large, concentrated volumes of CO2 are produced) and subsequently purified, compressed and transported. Some CO2 can be used for …