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Showing 1 to 20 of 64 for “"Monazite"”.
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Investigation of the monazite chemical dating technique
… microprobe (EMP) method for chemical dating of monazite, we chemically analyzed selected suites of monazite grains that were previously dated by standard U/Pb isotopic methods at three laboratories each equipped with a sensitive high resolution ion microprobe (SHRIMP). Representing diverse …
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A hydrometallurgical comparison between the caustic and sulphuric acid cracking of steenkampskraal (skk) monazite
… earths are hosted in the dominant mineral called monazite. In order to free the REEs from the monazite crystal, it requires “cracking” from the lattice such that it may be soluble in aqueous solution from which it undergoes purification. Two methods of cracking are usually employed in processing …
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The crystal chemistry of MTO₄ compounds with the zicron, scheelite, and monazite structure types
The crystal structures of zircon, scheelite, and monazite are very closely related. All three have chains of alternating polyhedra and planes of closest packed or pseudo-closest packed cations. Using these similarities the unit cells of these structures can be placed in analogous orientations. This …
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Factors influencing the mobility of uranium, thorium and rare earth elements at the Steenkampskraal monazite, North Western Cape
… earth elements (REE), Th and U. Steenkampskraal monazite mine, situated 350 km north of Cape Town, has been found to be an excellent locality for the study of these elements, due to the high concentration of these elements in the ore as well as the ideal geology, which consists of low …
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New structural interpretation, microstructural analyses, and preliminary monazite geochronology of Proterozoic rocks in the central Manzano Mountains, New Mexico
… event. Geochronologic studies of metamorphic monazite grains will place time constraints on when movement occurred within the area. Metamorphic monazite grown during tectonic deformation can have incremental growth patterns such as rim and core features. The ability to relate grain orientation …
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Garnet-biotite thermometry, garnet-aluminum silicate-silica-plagioclase barometry, and Emp monazite geochronology of the early Proterozoic Ivanpah Mountains, eastern Mojave Desert, Se California
… garnet studied; Electron Microprobe Analysis on monazite, using U-Th-Pb radioactive decay, suggest metamorphism occurred between 1752 +/- 86 Ma and 1689 +/- 34 Ma, similar to the age of the Yavapai terrane (∼1.70--1.69 Ma). These ages are constrained from six monazite grains included in three …
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Testing the driving mechanisms for exhumation of the Greater Himalayan zone in eastern Bhutan: Implications of split-stream zircon and monazite geochronology
… and lower (GHZl) structural levels, zircon and monazite from twenty samples from the Lesser Himalayan zone (LHZ) and the GHZ were analyzed for U–Th–Pb isotopes and trace-element abundances using split-stream laser-ablation inductively coupled plasma mass spectrometry (LA-ICPMS). …
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Monazite Geochronology of the Madison Mylonite Zone and Environs, Southwestern Montana: With Implications for Precambrian Thermotectonic Evolution of the Northern Wyoming Province
… is preserved in metamorphic zircon rims and monazite growth throughout the Snowy shear zone (SSZ) and the Madison mylonite zone (MMZ), South Madison Range, Montana. Comparison of U-Pb and U-Th-Pb ages yielded by monazite grains from both shear zones and zircon rims from SSZ, a new timing for …
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Tracking multistage deformation within an ultrahigh-pressure terrane: zircon and monazite microstructures and petrochronology from shear zones of the Western Gneiss Region, Norway
… and EBSD data from zircons and monazites to investigate the timing ofUHP metamorphism, exhumation, and deformation during these events. Samples werecollected from eclogites, orthogneisses, and paragneisses within five tens-of-meters scaleshear zones exposed in southern and …
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The development and application of microanalytical (U-Th)/He thermochronology
… of He in strongly zoned minerals, such as monazite. He diffusion experiments on monazite indicate that the closure temperature for (U-Th)/He thermochronometry is between 206°C and 286°C, but varies from grain to grain, even within suites of crystals obtained from one rock. This may be due …
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Eo-Variscan Orogenesis in the Guilleries Massif, Catalan Coastal Ranges, Northeastern Spain Recorded by U-Th-Pb ages of Monazite Inclusions in Metamorphic Garnet
… porphyroblasts, folded S1 inclusion trails with monazite are truncated by the regionally dominant S2 cleavage. Andalusite + cordierite grade rocks and S2 are syntectonic with the 323 Ma Susqueda Diorite. In the aureole of the Susqueda Diorite, contact metamorphism reached pyroxene + garnet + …
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CRYSTAL CHEMISTRY AND PHYSICAL-CHEMICAL BEHAVIOR OF REE-BEARING PHOSPHATES AND ARSENATES: THE CASE STUDY OF MT. CERVANDONE
… natural Rare Earth Elements-bearing phosphates [monazite-(Ce), nominally Ce(PO4), and xenotime-(Y), nominally Y(PO4)] and arsenates [gasparite-(Ce), nominally Ce(AsO4), and chernovite-(Y), nominally Y(AsO4)], from the hydrothermal quartz-bearing fissures outcropping at Mt. Cervandone (Lepontine …
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Behaviour of Critical Metals During Smelting of Copper Concentrates from Olympic Dam Plant, South Australia
… compounds (magnetite, delafossite and monazite), as well as slag evolution in terms of phase assemblages and textures. Energy loss measurements of Fe-L3 edge shift between atom columns into specific cation sites within EF magnetite show this has one of the lowest inversion parameters …
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Tectonics of the southern Annapurna Range, central Nepal Himalaya
… above the MCT. Preliminary Th-Pb dating of monazite suggests that this normal fault may have been active during slip on the MCT. The presence of such a proximal normal fault slipping synchronously with the MCT challenges some current representations of dynamic models for the evolution of the …
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Sediment-hosted Zn-Pb-Ag (+ Cu) deposits in the Mount Isa region: An epigenetic approach to mineralisation
… (>50ºC) temperature gradient across the orebody. Monazite inclusions within silica-dolomite alteration produce ages from 1623 ± 25 Ma to 1587 ± 43 Ma, constraining the maximum age of Cu-Zn-Pb-Ag mineralisation. Monazite from the 1100 level Cu orebody produces a range of ages from 16201360 Ma, …
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Rare Earth Extraction from Clayey Waste Materials by Alkali Pretreatment
… leaching has been proposed to recover REEs from monazite, which served as a proxy for the rare earth phosphates identified in coal-based clays. In this process, monazite can be decomposed at 80 oC. The following ammonium sulfate leaching was conducted under less aggressive conditions (i.e., pH 4 …
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Crustal melting in the Himalayan orogen : field, geochemical and geochronological studies in the Everest region, Nepal
… Quantitative measurement of REE and Y in monazites and xenotimes, that were later dissolved and dated by U-Pb IDTIMS, revealed monazite growth at temperatures appropriate for crustal melting (>650⁰C) between 25.4 and 24.8 Ma, suggesting that anatexis was ongoing at that time. Further …
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The Effect of Composition on the High-Pressure Behavior of Rare-Earth Phosphate Minerals
… CePO4 and GdPO4 are isostructural with monazite (P21/n), and TbPO4, YPO4, and ScPO4, are isostructural with xenotime (I41/amd). Raman spectra are consistent with previous studies and high-pressure spectra showed no phase transitions up to 10 GPa under hydrostatic conditions. The spectra …
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Bedrock and surficial geology of the southern half of the Montezuma 7.5' quadrangle, central Colorado Front Range, Colorado, USA
… and metamorphism based on metamorphic monazite growth between ~1.43 Ga and ~1.42 Ga has previously been recognized in some areas of the Montezuma quadrangle and the Mount Blue Sky quadrangle east of it. Bedrock geologic mapping, structural analysis, and U-Pb LA-ICP-MS zircon …
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The Proterozoic ancestry of the Colorado Mineral Belt : ca. 1.4 Ga shear zone system in central Colorado
… shear zone segments. In situ electron microprobe monazite dating of mylonites of the Colorado Mineral Belt shear zone system, coupled with field studies of relative timing of shearing and pluton emplacement, demonstrate a ca. 100 Ma history of recurrent shearing. This history involves movement at …
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