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Showing 1 to 20 of 75 for “"40Ar"”.
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Determination of the Spectroscopic Quadrupole Moment of 40Ar
… of iThemba LABS to determine the Qs(2+1 ) of 40Ar. A beam of 40Ar at a laboratory energy of 134.94 MeV was Coulomb excited on a 194Pt target at a safe distance between nuclear surfaces of 6.5 fm. The backward scattered 40Ar particles were detected by an S3-CD double sided silicon detector at a …
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Measurement of the (e,e') cross section for 12C, 48Ti, 27Al and 40Ar
In the upcoming deep underground neutrino experiment (DUNE), Liquid Argon Time Projection Chambers (LArTPCs) will be used as the detector technology, and argon will be used as the nuclear target. In order to reduce the systematic uncertainties on the extracted oscillation parameters, a more precise …
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40Ar/39Ar, AFT and (U-Th)/He thermochronologic implications for the low-temperature geological evolution in SE Sweden
… thermal evolution, from c. 500 °C to c. 50 °C. 40Ar-39Ar geochronology on hornblende, muscovite and biotite, was applied to determine cooling from c. 500 °C to c. 300 °C, whereas apatite fission-track (AFT) and (U-Th)/He thermochronology were used to determine the thermal evolution between c. …
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Heavy-ion double charge exchange reactions as tools for 0bb decays. The 40Ca(18O,18Ne)40Ar reaction at 270 MeV by using MAGNEX
… results have established that the transition to 40Args: is dominated by the direct processes. Finally, an innovative technique to infer on the nuclear matrix elements by measuring the cross section of a double charge exchange nuclear reaction was proposed. The main assumption are that the DCE …
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The Role of Magmatism in the Catalina Metamorphic Core Complex, Arizona: Insights from Integrated Thermochronology, Gravity and Aeromagnetic Data
… evidence of zircon growth at <40 Ma.</p> <p>40Ar/39Ar data from the Wilderness suite sills indicate that the majority of the older 40Ar/39Ar apparent ages from both potassium feldspar and mica were obtained from the structurally higher sills in the main range, and the younger 40Ar/39Ar …
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Dynamic topography of the western Great Plains : geomorphic and 40Ar/39Ar evidence for mantle-driven uplift associated with the Jemez lineament, New Mexico and SE Colorado
… canyons and inverted, basalt-capped mesas. 40Ar/39Ar ages are used to define an episodic eruption history in the Raton-Clayton volcanic field and to quantify denudation rates from flow-capped paleosurfaces. Several datasets indicate patterns of surface topography that are consistent with …
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The use of detrital mineral thermochronology to explore relationships among climate, erosion, and tectonics in the Nepal Himalaya
… are evaluated using statistical comparisons of 40Ar/39Ar ages from Nepal and catchment area-elevation distributions. Bedrock 40Ar/39Ar data indicate that erosion rate estimates from detrital thermochronology yield the same rate as the traditional approach of analyzing bedrock cooling ages over a …
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High-Resolution Correlation of a Time-Bounded Unit of the Pisco Formation, Peru
… an interval bounded by two time markers, an 40Ar/39Ar-dated white tuff at the base and an 40Ar/39Ar-dated tuff couplet at the top. This interval was chosen because of the continuity and excellent exposure of the tuff beds at six distinct locations in a linear transect 30 km long. Correlation …
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⁴⁰Ar/³⁹Ar and U-Pb geochronological constraints on the thermal and tectonic evolution of the Connemara Caledonides, Western Ireland
… apparent ages using higher resolution U-Pb and 40Ar/ 39Ar geochronometers. The results indicate that arc magmatism, sillimanite-grade metamorphism, anatexis, and late fluid infiltration spanned only about 12 million years. Cooling following the metamorphic peak was actually relatively rapid at …
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Antarctica's Geologic and Ice Sheet History from Isotopic Sedimentary Provenance Studies
… fraction and employed isotopic measurements - 40Ar/39Ar on detrital hornblende and biotite grains, U-Pb on detrital zircons. I have also employed Nd isotope measurements on the terrigenous fine (< 63µm) fractions of these same samples. Chapter 2 is published in the journal Paleoceanography, and …
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Evolution of the Kingman Arch, southern Nevada
… Extensional Corridor. Apatite fission track and 40Ar/39Ar thermochronological analyses were conducted for granite samples collected from a 4.5 kilometer thick Precambrian section in the central McCullough Range. 40Ar/ 39Ar data suggest slow cooling of the Kingman Arch between 1000 to about 560 …
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Neon, Helium and Argon isotope systematics of the Hawaiian hotspot
… the MORB correlation line. The values in the 4He/40Ar* (40Ar* denotes radiogenic Ar) versus 4He diagram imply open system fractionation of He from Ar, with a deficiency in 4He. Calculated 4He/40Ar*, 3He/22Nes (22NeS denotes solar Ne) and 4He/21Ne ratios for the sample suite are lower than the …
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Die Isotopenzusammensetzung von Helium, Neon und Argon in ultramafischen Gesteinen des subkontinentalen lithosphärischen Mantels im Gebiet des Roten Meeres
… ist charakterisiert durch eher niedrige 40Ar/36Ar-Verhältnisse im Vergleich zu normaler Asthenosphäre. Eine Probe wies hohe, auf in situ radiogene Beiträge zurückzuführende 40Ar/36Ar-Werte auf. Das errechnete Modell-Alter von 580-740 Ma entspricht dem Bildungsalter der Lithosphäre selbst. …
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Edelgase als Tracer für Wechselwirkungen von Krusten- und Mantelfluiden mit diamantführenden Gesteinen des östlichen Baltischen Schildes
… thermische Entgasungsmuster für <sup>40Ar und <sup>36Ar zeigen, ist <sup>36Ar in Fluideinschlüssen konzentriert. Das <sup>40Ar/<sup>36Ar-Isotopenverhältnis der Fluideinschlüsse von Lamproiten aus Kostamuksha ist antikorreliert mit der durch thermische Extraktion bestimmten Gesamtmenge …
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Mesoproterozoic tectonic evolution of southwestern North America : protracted intracratonic deformation, sedimentation, and differential exhumation in Grand Canyon and the Rocky Mountain Region
… date the onset of deposition at ca. 1254 Ma. 40Ar/39Ar Kfeldspar thermochronology in Grand Canyon indicates that basement rocks cooled through 150˚ C between about 1300 and 1250 Ma, refining exhumation rates of basement rocks just prior to Unkar deposition. Abrupt thickness and facies changes …
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Tectonic and climatic controls on orogenic processes : the Northwest Himalaya, India
… orogen. Along the southern Himalayan front new 40Ar/39Ar white mica and apatite fission track (AFT) thermochronologic data provide the opportunity to determine the history of rock-uplift and exhumation paths along an approximately 120-km-wide NE-SW transect spanning the greater Sutlej region of …
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A Second North American Hot-spot: Pleistocene Volcanism in the Anahim Volcanic Belt, west-central British Columbia
… I report new whole-rock geochemical data and 40Ar/39Ar age determinations for two previously little-studied cone fields around Satah Mountain and Baldface Mountain in the central part of the AVB. Individual volcanic centres in these fields are generally small in extent and volume and most have …
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Kinematics and timing of normal faulting in a metamorphic core complex: Grouse Creek Mountains, Utah
… Utah, in the central Grouse Creek Mountains. 40Ar/39Ar thermochronology and kinematic studies indicate two periods of motion along the MMSZ in Eocene and Late Oligocene to Early Miocene time and motion along the sub-parallel Upper detachment in Middle Miocene time. Eocene fabrics record …
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