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Showing 1 to 14 of 14 for “"Sr isotopes"”.
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Lead isotopes as a palaeodietary tracer in southwestern South Africa
This thesis evaluates the utility of lead (Pb) isotopes, in combination with strontium (Sr) isotopes, as a geochemical tracer for studying the palaeodiets and palaeo-landscape usage in southwestern South Africa. Isotopes of light elements, carbon (C), nitrogen (N), oxygen (O), and sulphur (S), are …
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The accretion of lower oceanic crust
… alteration of the ocean crust, including Sr and O-isotopes, to investigate and quantify the role of hydrothermal circulation during the accretion of the ocean crust. The second method uses diffusion based geospeedometry techniques to determine cooling rates in the ocean crust. Samples from …
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Petrogenesis of kimberlites from South Africa and lamproites from Western Australia and North America
… element contents, while the range in N d and Sr isotopes encompasses much of that reported for various upper and lower crustal rocks. It is argued that these features are not due to crustal contamination during magma ascent, rather they are source and extraction phenomena. The mantle source …
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The Box Ankle and Ocmulgee shear zones of central Georgia: a study of geochemical response to Southern Appalachian deformation events
… age discordancy. Isotopic re-equilibration of Sr Isotopes did not occur on a cm whole rock scale during deformation. Porphyroclasts In the Ocmulgee shear zone retained partial Sr Isotopic signatures of the shear zone protolith. In contrast, Rb-Sr Isotope systems In the Box Ankle fault were …
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The Evolution and Impact of Weddell Sea Deep Water
… provenance (detrital radiogenic Nd and Pb isotopes), water mass provenance (authigenic Pb isotopes), and identification of marine forward and reverse silicate weathering processes (dissolved stable Si and radiogenic Sr isotopes, fine grained K’/Ar ages). Overall, the novel findings of this …
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Syntectonic deposition and paleohydrology of the spring-fed Hualapai Limestone and implications for 5-6 MA integration of the Colorado River system through Grand Canyon : evidence from sedimentology, geochemistry and detrital zircon analysis
… increase in meteoric water input through time. Sr isotopes, though variable, show an up-section decrease in 87Sr/86Sr and confirm a freshwater origin for the Hualapai Limestone. These data, plus facies analysis, suggest that waters that fed the Hualapai Limestone contained a significant …
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Geodynamic Development of the South China Block from Precambrian to Cretaceous: Constraints from Geology Geochemistry and Geochronology
… rock Lu-Hf isotope data, whole rock Sm-Nd and Rb-Sr isotopes data, rock major and trace element data. Geochronology data concentrate on U-Pb zircon and monazite data for the crystallisation ages of igneous rocks and near-peak metamorphism although lower-temperature closure ages have also been …
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The possibility of an impact-related origin of quasi-conglomerate pseudotachylytes on Barra, Outer Hebrides, Scotland, an integrated study
… Geochemical analyses of the Sm / Nd and Rb / Sr isotopes were performed to exclude a fluid assisted process of quasi-conglomerate formation or a remobilisation during the later intrusion of the abundant dykes.;In the mapped area, all outcrops show some degree of pseudotachylyte occurrence. The …
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Paleofluid Flow, Fracturing and Reservoir Implications in Foreland basins: an example from the Cretaceous Qamchuqa Formation, Kurdistan Iraq
… analysis, petrographic study, stable C, O and Sr isotopes, fluid inclusion data, mineralogical and geochemical investigations reveals at least two main phases of multiple fluxes of hydrothermal fluid circulation during the Zagros Orogeny at the end of the Cretaceous and in Miocene to Pliocene …
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MULTISCALE GEOCHEMICAL STUDY OF THE CORNO ALTO COMPLEX (ADAMELLO BATHOLITH)
… strong enrichment in Ba and to a minor extent in Sr (Ba + Sr ≈ 1100-1900 ppm). Other geochemical features include a moderately-to-strong enrichment in LREE over HREE (LaN/YbN > 20) and Y (Sr/Y > 40). U-Pb geochronology on zircon shows an east-west trend of decreasing ages in the intrusive complex, …
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Mineralogy, Chemistry & Flux of Suspended Sediments in Himalayan Rivers
… sediment provenance were ruled out, using Nd and Sr isotopes, as the cause of the seasonal or downstream sediment changes. It is concluded that the seasonality of mineral phases likely arises from the preferential sorting and easy transfer of micaceous sediments in the early monsoon, such that …
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Geodynamic Evolution of the Aegean Back-arc and its Implication for Associated Precious and Base Metal Mineralization
… geochemical, and isotopic analyses (Pb, Sr, δ34S and δ18O) of galena (PbS) and ore-associated hydrothermal barite (BaSO4). New galena Pb isotope data complemented by Pb isotope data of galena from the literature exhibit a range of isotopic ratios, with a resolvable geologic pattern. …
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Petrologic Significance of Multiple Magmas in the Quottoon Igneous Complex, NW British Columbia and SE Alaska
… (24-34) than in suite I. Suite I rocks have Sr concentrations <750 ppm, avg. LaN/YbN = 10.4, and initial 87Sr/86Sr ratios that range from 0.70513 to 0.70717. The suite II rocks have Sr concentrations >750 ppm, avg. LaN/YbN = 23.1, and initial 87Sr/86Sr ratios that range from 0.70617 to …