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Showing 1 to 18 of 18 for “"U/Pb Ages"”.
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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
… A total of 2,163 new detrital zircon U-Pb ages were obtained from 16 samples to confirm the published provenance of the sandstones and/or recover new grain-age populations. The U-Pb ages reveal the major sources for zircons: Permian-Triassic, Jurassic, and Cretaceous arc rocks, the …
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Thermo-tectonic record of hyperextension, structural inversion, and foreland basin evolution of the eastern and central Pyrenees
… chapters integrate zircon, apatite, and rutile U‐Pb ages from the Agly and Saint Barthélémy massifs that provide new constraints to understand the decoupled versus coupled extensional evolution, exhumation timing of the middle‐lower crust, and the age of juxtaposition of the upper crust granitic …
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U/Pb Zircon Ages of Plutons from the Central Appalachians and GIS-Based Assessment of Plutons with Comments on Their Regional Tectonic Significance
… region. SIMS (secondary ion mass spectrometry) U/Pb ages of zircons were obtained for ten plutons (Leatherwood, Rich Acres, Melrose, Buckingham, Diana Mills, Columbia, Poore Creek, Green Springs, Lahore and Ellisville) within Virginia. These plutons are distinct chemically, isotopically, and show …
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Metamorfismo ercinico di bassa-pressione: evoluzione tettonico-metamorfica del complesso di mandatoriccio (massiccio della Sila - Calabria)
… into the intermediate level during the late stages of the Hercynian orogeny. Up to now, advanced petrologic studies have been focused mostly in understanding P-T evolution of deeper crustal levels and magmatic bodies, whereas the metamorphic history of the shallower crustal levels is poorly …
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Characterization and chronology of refractory inclusions (CAIs) in the CV3 chondrite NWA 4502
… Rb-Sr and uranium) compositions as well as U-Pb ages of five coarse-grained igneous inclusions (Type A CAIs 1 and 4a, Type B CAIs 5, 6 and 7) from the CV chondrite North West Africa (NWA) 4502 the second largest CV chondrite so far after Allende. At a mineralogical level, NWA 4502 is rather …
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Characterization and chronology of refractory inclusions (CAIs) in the CV3 chondrite NWA 4502
… Rb-Sr and uranium) compositions as well as U-Pb ages of five coarse-grained igneous inclusions (Type A CAIs 1 and 4a, Type B CAIs 5, 6 and 7) from the CV chondrite North West Africa (NWA) 4502 the second largest CV chondrite so far after Allende. At a mineralogical level, NWA 4502 is rather …
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The Box Ankle and Ocmulgee shear zones of central Georgia: a study of geochemical response to Southern Appalachian deformation events
… south and east of the Pine Mountain window. U-Pb ages of zircons constrain the timing of deformation along the Box Ankle and Ocmulgee faults at 304 ± 144 and 335 ± 7 Ma respectively. A contrast in zircon response to high grade deformation from both fault zones is observed. The response of …
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A multi-technique provenance study of the Oligocene : recent Nile cone sediments and River Nile hinterland
… Highlands since this time. Zircons with U-Pb ages and hafnium isotope signatures compatible with the Ethiopian LIP have been supplied to the Nile cone since at least the Miocene (16 Ma). Such zircons were not observed in Oligocene 2 delta sediments, but Sr, Nd and Hf isotope data for …
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Detrital zircon geochronology of the Upper Miocene Boleo Formation in the Santa Rosalia, Baja California Sur, Mexico
… age is poorly constrained. We carried out a U-Pb detrital zircon study of the Boleo Formation to constrain its maximum depositional age. The Boleo Formation has basal limestone and gypsum sections that may be time transgressive. These are overlain by a much thicker clastic sequence, with …
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Origin and Tectonic Evolution of Gondwana Sequence Units Accreted to the Banda Arc: A Structural Transect through Central East Timor
… of the active Banda Arc. Our field studies and U/Pb zircon age analysis helped assign most units to either Asian or Australian affinity. Detrital zircon from uplifted Banda forearc units (Asian affinity) have U/Pb ages as young as 80 Ma (Standley and Harris, in press). In contrast, analysis of …
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Tectonics of the southern Annapurna Range, central Nepal Himalaya
… Whole-rock Nd isotopes and detrital zircon U-Pb ages allow the discrimination of hanging wall and footwall rocks of the MCT. Application of these techniques in the Annapurna Range of central Nepal unambiguously locates the MCT. Microstructural analyses confirm the presence of a thrust-sense …
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The Global Detrital Zircon Database: Quantifying the Timing and Rate of Crustal Growth
… and for modern river sediments. Hf isotope model ages were also incorporated into the database where grains were dated with both U-Pb and Hf isotopes. The Hf isotope model ages suggest that the majority of detrital zircons U-Pb ages reflect crustal recycling events that generated granitic …
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Paleogeography of Western North America: Insights from Detrital Zircon U-Pb Geochronology and Hf Isotope Geochemistry
… using modern analytical techniques including U-Pb geochronology and Hf isotope geochemistry of detrital zircons, as well as, geologic mapping and paleocurrent analysis. The Neoproterozoic through Pennsylvanian Yukon-Tanana terrane (YTTs) in the Coast Mountains of southeastern Alaska, the …
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Petrogenesis of Mesoarchean high-K rocks in the Kaapvaal Craton: Investigating the Boesmanskop Alkaline Complex and Salisbury Kop batholith
… chemistry, whole-rock compositions, and U-Pb zircon geochronology, alongside Rb-Sr and Sm-Nd isotopic data and phase equilibrium modeling for the BAC rocks. The BAC includes coarse-grained syenite, quartz monzonite and leucogranite. Some syenites display porphyritic textures that indicate …
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INNOVATIVE AND CONVENTIONAL APPROACHES TO DETRITAL ZIRCON PROVENANCE ANALYSIS: LOOKING TO THE PAST, PRESENT, AND FUTURE
… tool in our understanding paleo-fluvial drainages, erosion of landscapes, paleogeographic reconstructions, and regional geologic and tectonic histories. Here, we examine the utility of multiple provenance analysis techniques through their application to paleo, modern, and synthetic detrital …
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Geochemical and Geochronological Constraints on the Origin and Evolution of Rocks in the Active Woodlark Rift of Papua New Guinea
… chapter uses a panoply of geochronological (U-Pb zircon) and geochemical (Lu-Hf and Sm-Nd isotopes, trace/REEs, and major elements) tools to investigate the origin the major lithostratigraphic units in the Woodlark Rift. Important findings in this chapter include the establishment of a tectonic …
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LITHIUM ENRICHMENT IN ANATECTIC PEGMATITES: NEW INSIGHTS FROM THE THERMOMETAMORPHIC AUREOLE OF THE ADAMELLO BATHOLITH
… melting in low pressure migmatites. Zircon U-Pb ages for all pegmatites in the area, point to the same age of the Adamello pluton intrusion, ca. 38 Ma, and trace elements compositions helped to outline the differences in the geochemical signature between pluton-derived and metapelite-derived …
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Multidisciplinary investigations of the Chaman strike-slip fault along the western Indo-Asian collision boundary, Pakistan
… the Afghan block at the time of emplacement. U-Pb emplacement ages from granitic samples in the Khwaja Amran-Spinatizha area suggest that granitic intrusions within the Chagai-Ras Koh ceased by ~58 Ma as in the Kandahar arc. The fission track ages of ~35 Ma and ~20 Ma from the intrusive rocks of …