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Showing 1 to 20 of 47 for “"(U-Th)/He"”.
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Zircon (U-Th)/He Dates from Radiation Damaged Crystals: A New Damage-He Diffusivity Model for the Zircon (U-Th)/He Thermochronometer
Zircon (U-Th)/He (zircon He) dating has become a widely used thermochronologic method in the geosciences. Practitioners have traditionally interpreted (U-Th)/He dates from zircons across a broad spectrum of chemical compositions with a single set of ⁴He diffusion kinetics derived from only a …
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The development and application of microanalytical (U-Th)/He thermochronology
The (U-Th)/He thermochronmeter is the foremost tool available to geoscientists for the purposes of constraining the thermal evolution of the crust below 250°C. However, the potential of the technique is far from fully explored. The existing de facto (U-Th)/He age standard, the fluorapatite of Cerro …
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Complexities of (U-Th)/he zircon thermochronology through the lens of zonation and deep time
… 2021-09-17T02:34:21Z (GMT). No. of bitstreams: 3 THURSTON-DISSERTATION-2021.pdf: 7628080 bytes, checksum: c6371e102e8d2076914a6d80ba36302b (MD5) LICENSE.txt: 4212 bytes, checksum: f34acdd052283bdcad4f0c41ed62f8d4 (MD5) PROQUEST_LICENSE.txt: 4558 bytes, checksum: 7bedd7b222e270e25ba8827ce8e19f56 …
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Timing of erosional episodes in the Marble Canyon and Vermilion Cliffs region from apatite (U-Th)/He thermochronology
The history of incision of the Marble Canyon segment of Grand Canyon, and the rate of retreat of the Vermilion Cliffs portion of the Grand Staircase, are examined using a synthesis of new and published low-temperature thermochronology datasets. I test models for a 50-70 Ma Marble Canyon and …
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40Ar/39Ar, AFT and (U-Th)/He thermochronologic implications for the low-temperature geological evolution in SE Sweden
The Oskarshamn and Forsmark areas in the Fennoscandian Shield, SE Sweden, have been chosen as potential sites for hosting highly radioactive nuclear waste. To evaluate their respective suitability, the geological history of the bedrock in these two areas has been investigated. This study has …
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Geologic mapping and zircon (U-Th)/He thermochronology of the Avawatz Mountains, California; Implications for the eastern terminus of the Garlock fault
The Avawatz Mountains are located at the eastern tip of the left-slip Garlock fault where the fault intersects the NW-striking right-slip Southern Death Valley fault (SDVF). The Avawatz Mountains were constructed via late Cenozoic contractional deformation involving active thrust and/or …
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Exhumation, rift-flank uplift, and the thermal evolution of the Rwenzori Mountains determined by combined (U-Th)/He and U-Pb thermochronometry
Rising over 5 km along the border of Uganda and the Democratic Republic of the Congo, the Rwenzori Mountains represent an extreme example of basement rift-flank uplift in the western branch of the East African Rift, a phenomenon common throughout the East African Rift System and characteristic of …
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Long-term exhumation of landscapes along the Pacific-North American plate boundary as inferred from apatite (U-Th)/He and ArcGIS analyses
The Pacific-North American plate boundary is typified by transpression and convergence, yet the relationship between interplate deformation and long-term crustal shortening is not fully understood. The continuous belt of rugged topography that extends along the entire plate boundary is generally …
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Integrating apatite (U-Th)/He and fission track dating for a comprehensive thermochronological analysis: refining the uplift history of the Teton Range
Uplift of the Teton Range is primarily controlled by displacement across the range-front Teton normal fault. The Tetons comprise the footwall block while the hanging wall encompasses Jackson Hole valley and a portion of the Snake River. Relative to the rest of the Rocky Mountains, the Tetons …
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Timing and drivers of exhumation in the hinterland of the North American Cordillera from detrital zircon U-Pb and (U-Th)/He double-dating
The late Cretaceous to early Cenozoic hinterland of the North American Cordillera is widely recognized as an orogenic plateau. Although most studies suggest that this highland was in place by the Eocene, the timing and underlying drivers of the plateau’s development and eventual demise are not well …
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Deep-time tectono-thermal history of the northern us cordillera: understanding zircon (U-Th)/he thermochronology and its application to Idaho-Montana basement rocks
… an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2022-04-06 without embargo terms
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A combination of apatite fission track and (U-Th)/He thermochronometers to constrain the escarpment evolution in south eastern Australia: a case study of high elevation passive margins
In this project apatite fission track and (U-T)/He thermochronometers are used to determine the cooling history of rocks from the coastal (south eastern New South Wales) and the interior (Bathurst area) regions of the eastern Australia high elevation passive margin. Two traverses across the coastal …
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Miocene core complex development and coeval supradetachment basin evolution of Paros, Greece
This study evaluates the tectonosedimentary evolution of Paros, Greece using apatite and zircon (U-Th)/He dating to assess the currently accepted kinematic history and resolve controversy about the formation of and sources to the Paros supradetachment basin. Overdispersed and improbable results in …
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Helium and lead isotope geochemistry of oceanic volcanic rocks from the East Pacific and South Atlantic
The isotopic evolution of helium and lead in the Earth is coupled by virtue of their common radioactive parents uranium and thorium. The isotopic signatures in oceanic volcanic rocks provide constraints on the temporal evolution of mantle source regions and volcanic magmas. He and Pb isotopes were …
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Using thermochronology to constrain exhumation in the Swiss-Italian Alps
… were collected from Ticino, Switzerland and Northern Italy for thermochronological studies using the (U-Th)/He technique on zircon and apatite and fission track on subset of zircons. Nine samples were collected from the Lepontine Dome, north of the Insubric Line, six of which were in an …
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Isotopic characterization of bedrock, sediments, and minerals as provenance tools: Examples from an inselberg in the Mojave Desert of SE California
<p>Our understanding of the evolution of the Earth’s surface is driven by our knowledge and comprehension of the processes which shape the landscape. The source, formation, and transport pathways of sediment are critical components to understanding crustal processes and changes and are often …
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Rapporti tra tettonica e clima durante l'esumazione nelle Alpi Centrali. Evidenze dalla termocronologia e dall'analisi strutturale lungo il traforo ferroviario del Sempione
(U-Th)/He and fission-track analyses of apatite along deep-seated tunnels crossing high-relief mountain ranges offer the opportunity to investigate climate and tectonic forcing on the topographic evolution. In this study, the thermochronologic analysis of a large set of samples collected in the …
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Helium and lead isotope geochemistry of oceanic volcanic rocks from the East Pacific and South Atlantic
The isotopic evolution of helium and lead in the Earth is coupled by virtue of their common radioactive parents uranium and thorium. The isotopic signatures in oceanic volcanic rocks provide constraints on the temporal evolution of mantle source regions and volcanic magmas. He and Pb isotopes were …
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The igneous petrology, thermal history, and genesis of sedimentary rock-hosted Au deposits in the northern Battle Mountain mining district, Nevada
The Battle Mountain mining district in north-central Nevada hosts deposits of magmatic-hydrothermal origin, including porphyry, skarn, and distal disseminated deposits, as well as sedimentary-rock hosted Au deposits of uncertain origin. This dissertation examines the ages of magmatism and …
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The post-breakup evolution of the western Indian high-elevation passive margin
The tectonic development of the Western Indian high-elevation passive margin is complex. At least two major rifting events (India/Madagascar and India/Seychelles) and a major hotspot (The Reunion plume) are believed to have been instrumental in the formation and development of the margin. However, …
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