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Showing 1 to 20 of 20 for “"Lu–Hf"”.
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Zircon U-PB and LU-HF isotopic data from some peri-gondwana variscan terranes (Sardinia-Corsica block and calabropeloritan arc): new insights on the cenozoic geodynamic evolution of the central mediterranean basin
… in unraveling the peri-Tyrrhenian area evolution of the peri-Gondwana terranes, amalgamated during Variscan and widespread during Cainozoic opening (and closing) of Tethys, both Variscan and Tertiary rocks cropping out in the two Blocks have been investigated, either magmatic or …
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Thermochronology of ‘The Gap’, Western Australia
… aspects of their magmatic and metamorphic evolution; however much of the subsequent thermal history is yet to be age constrained. The thermal evolution of these basement regions is characterised by multiple overprinting events that make establishing unique relationships between dates, rates, …
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Unrecognized complexities of metamorphism : crystallization kinetics, reaction affinity, and geochronology
… rocks and the effects of garnet resorption on Lu-Hf garnet ages were examined through numerical simulations of these processes. Concerning scales of disequilibrium, thirteen porphyroblastic datasets, previously measured using X-ray computed tomography, were examined by numerically simulating …
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Archean continental crust formation and the rise of atmospheric oxygen
… rise of an oxygenated atmosphere. The volume of continental crust on the earliest Earth is a critical parameter for constraining the chemical evolution of major terrestrial reservoirs, and radiogenic isotope signatures document this varying geochemical character. Chapter 1 presents a …
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Geochemical and Geochronological Constraints on the Origin and Evolution of Rocks in the Active Woodlark Rift of Papua New Guinea
… Letters (2011 v. 309, p. 56 - 66), is entitled `Lu-Hf garnet geochronology applied to plate boundary zones: Insights from the (U)HP terrane exhumed within the Woodlark Rift'. This chapter focuses on the use of the Lu-Hf isotopic system to date garnets in the Woodlark Rift. Major findings of this …
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Evolution of continental crust in the Proterozoic : growth and reworking in orogenic systems
… century, the use of coupled in situ zircon U–Pb, Lu–Hf and O isotope analyses as a tool to address these questions have increased exponentially. Numerous compilations of ever growing datasets have been presented, leading to new, and sometimes contrasting models of continental growth. Many of …
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The geochemistry and geochronology of the barby formation in the sinclair area, Southern Namibia
… some alkaline rocks are present. U-Pb dating and Lu-Hf isotopic microbeam analyses were made on zircon and baddeleyite grains from four samples using cathodoluminescent images. A Barby rhomb porphyry sample gives an U-Pb baddeleyite age of 1217 ±2 Ma and a Barby felsic tuff has an 207Pb/206Pb …
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ΜΕΛΕΤΗ ΠΡΟΕΛΕΥΣΗΣ ΑΡΧΑΙΩΝ ΚΕΡΑΜΕΙΚΩΝ ΜΕ ΝΕΤΡΟΝΙΚΗ ΕΝΕΡΓΟΠΟΙΗΣΗ ΣΤΑΤΙΣΤΙΚΗ ΑΝΑΛΥΣΗ
… ANALYSIS. THE FIRST PART OF THE STUDY INCLUDED THE INVESTIGATION OF PROBLEMS ARISING FROM THE DIRECT COMPARISON OF TRACE ELEMENT COMPOSITIONS OF NATURAL CLAYS AND CERAMICS. THREE OF THE MOST IMPORTANTFACTORS THAT MAY ALTER THE CLAY COMPOSITION DURING ITS TREATMENT (MIXING, PURIFICATION AND …
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Saarisen ultramafisen intruusion petrografia, geokemia ja geokronologia
… Lapinlahden kunnassa Saarisen järven alueella sijaitseva pienehkö ultramafinen intruusio, joka poikkeaa selvästi sitä ympäröivistä arkeeisista TTG-assosiaatin kivistä. Lapinlahti sijaitsee Fennoskandian arkeeisen kratonin reuna-alueella ja geologiset rakenteet jakaantuvat sekä …
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Stratigraphic response to Cordilleran processes along the south central Andean margin
… Chapter 1 applies detrital zircon U-Th-Pb and Lu-Hf isotopic datasets as a powerful methods for evaluating long-term, regional geologic patterns and the processes of crustal addition, removal, and recycling to help resolve the onset of Andean subduction, and the relationships and feedbacks …
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Geodynamic Development of the South China Block from Precambrian to Cretaceous: Constraints from Geology Geochemistry and Geochronology
The geo-tectonic evolution of the South China block is subject to debate. Most articles tend to subdivide the South China block into two sub-ordinate blocks (Yangtze and Cathaysia), with a central Sibao (Jiangnan) Orogen, although there are also suggestions for a separate eastern (Tolo) block. …
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Banda Forearc Metamorphic Rocks Accreted to the Australian Continental Margin: Detailed Analysis of the Lolotoi Complex of East Timor
… and peak pressures of 5 to 8 kbar for garnet-aluminosilicate-quartz-plagioclase assemblages. Analyses of amphibole in amphibolites yield temperatures of 550°C to 650°C and pressures of 6 to 7 kbar. Lu-Hf analyses performed on garnet samples from two massifs in East Timor yielded four ages with …
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Compositional Analysis of the Martian Meteorites Northwest Africa 6342 and Northwest Africa 10961
… This makes the study of shergottite samples invaluable to understanding the geological evolution of that planet. Electron microprobe analyses, bulk elemental composition calculation, and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) were used to analyze the composition …
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Origin of the Kleva Ni-Cu sulphide mineralisation in Småland, southeast Sweden
… and confirms its temporal association with the voluminous TIB magmatism. Major- and trace element systematics are in accordance with a basaltic magma that formed through partial melting of a metasomatically refertilised mantle wedge underneath an Andean-type continental magmatic arc. Lu-Hf …
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Sediment-hosted Zn-Pb-Ag (+ Cu) deposits in the Mount Isa region: An epigenetic approach to mineralisation
… 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, reflecting …
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Estratigrafía y evolución magmática del Grupo Los Menucos (Triásico), provincia de Río Negro, Argentina
… permitió reconocer tres momentos en la evolución geológica de esta región durante el Mesozoico. Un primer momento ligado al Triásico Temprano a Medio, el segundo ligado al Triásico Tardío y el tercero vinculado con el Jurásico Temprano. El desarrollo durante el Triásico Temprano a Medio se …
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Across- and along-strike structural and geochronological variations of the Nashoba-Putnam and Avalon terranes, eastern Massachusetts, Connecticut, and Rhode Island, southeastern New England Appalachians
… channel flow occurred during the latest Silurian to earliest Carboniferous Acadian orogeny, which resulted from the accretion of the Avalon terrane. Foliation orientations in the northwest-dipping Nashoba-Putnam terrane show a decrease in dip angle from subvertical and moderate dips in the …
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Sediment incorporation into continental arc systems and paleogeography of the western North American Cordillera: Insights from the North Cascades, Washington
… proposed to play a significant role in the evolution of the arc by potentially triggering high-flux magmatism and driving newly formed crust towards more felsic compositions. Therefore, it is important to document the mechanisms by which sediment is transferred from the surface to between …
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The tectonic evolution of the Southern Granulite Terrane of India and its role in the amalgamation of Gondwana.
… metamorphism. The coupled U-Pb and Lu-Hf isotopic study of the metasedimentary rock packages from the Salem Block mainly yielded late Archaean to early Palaeoproterozoic (ca. 2.7 - 2.45 Ga) detrital zircon ages with εHf values between +0.3 and +8.8, suggesting derivation from largely …
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Geochemical and fluid dynamic investigations into the nature of chemical heterogeneity in the Earth's mantle
… length scales of chemical variability, the evolution with time of geologic systems, the physical properties of mantle rocks, and the driving forces of phenomena which govern heat and mass transport in a dynamic earth. This dissertation attempts to add to this knowledge by examining the trace …