Papers 5792
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Abstract The large amount of geochemical variability in peridotitic and pyroxenitic xenoliths exhumed by Eocene to present-day magmas in Patagonia provides a unique opportunity to investigate the depletion and enrichment processes affecting the lithosphere in proximity of subduction settings and their relationships with magmatism. In this study, a review of the geochemical features of the Patagonian ultramafic xenoliths coupled with new Sr Nd isotopic data on clinopyroxene separates from represe...
Abstract Large quantities of continental lithosphere are known to enter the mantle during continental rifting, but their possible contribution in the generation of melts under a nascent ocean remains enigmatic. Here we report new in situ chemical and Sr Pb isotopic data for volcanic glass and feldspar in volcanic breccia in the South China Sea (SCS) formed after cessation of SCS spreading. Similar to volcanic breccia (whole rocks), the volcanic glasses and feldspars in breccia can also be groupe...
Abstract Post-collisional volcanic rocks associated with the Variscan orogeny are preserved in relicts of Late-Paleozoic volcano-sedimentary basins in the Bohemian Massif (central Europe). They include both the Late Carboniferous calc-alkaline and the Early Permian tholeiitic suites, which were emplaced in an extensional intracontinental setting. Both suites were derived from an enriched continental lithospheric mantle and underwent early fractionation of mafic silicate minerals. A second period...
Abstract Archean cratons provide windows to the crustal evolution history in the early Earth. The Dharwar Craton is one of the major cratonic blocks in Peninsular India and is composed of several ancient microcontinents where multiple continental growth and recycling occurred from 3.8 to 2.5 Ga. Here we investigate a suite of magmatic rocks (including granitoids, mafic magmatic enclaves, ultramafic inclusions and synplutonic mafic dyke) from the western margin of the Eastern Dharwar Craton which...
Abstract Archean granitoids provide us with an insight into the accretion and differentiation of early continental crust. We report the study of a dioritic to granitic rock association occurring in the Hongzhao region of the Daqingshan–Wulashan Terrane at the southern periphery of the Yinshan Block in western North China Craton. Zircon U Pb dating reveals that the Hongzhao plutonic suite was emplaced within a short period (2.48–2.46 Ga) at the Archaean–Proterozoic transition. Four types of rocks...
Abstract New U Pb ages and geochemical and isotopic data from leucogranites within the central Sanandaj–Sirjan zone (SSZ) of the Zagros orogen in Iran enable an evaluation of a migrating magmatic system in response to subduction of Neo-Tethyan lithosphere. The Esfajerd leucogranites, from the Golpaygan region of the Muteh–Golpaygan metamorphic complex, are composed mainly of tourmaline and two-mica leucogranites and are characterized by strongly peraluminous compositions. SIMS U Pb zircon ages i...
Abstract The Abu Dabbab rare-metal granite in the Central Eastern Desert of Egypt is a peraluminous alkali-feldspar leucogranite stock with minimum melt composition of albite-rich haplogranite and is characterized by economic resources of columbite group minerals (CGM) and cassiterite. The bulk-rock trace element composition is characterized by very low Sr, Ba, REE+Y, Zr, Ti, Ni, Cr concentrations, elevated Li and F, and very high Sn, Ta and Ga. The non-chondritic, low Y/Ho ratios and extremely ...
Abstract The early Permian Kalatongke Ni Cu sulfide deposit in the Central Asian Orogenic Belt (CAOB) is the most important Ni Cu deposit in northern Xinjiang, NW China. It is hosted mainly by mafic intrusions, which is in contrast to deposits in the Eastern Tianshan area of eastern Xinjiang that are hosted mainly by ultramafic intrusions. The controls on sulfide mineralization in the Kalatongke mafic intrusions are poorly constrained relative to the ultramafic intrusions. Here we use amphibole ...
Abstract Ultramafic xenoliths are rarely found at convergent plate margins. A notable exception is in the Betic Cordillera of southern Spain, where the eruption of xenolith-bearing alkaline basalts during the Pliocene post-dated the Cenozoic phase of plate convergence and subduction-related magmatism. Mantle xenoliths of the monogenetic volcano of Tallante display extreme compositional heterogeneities, plausibly related to multiple tectono-magmatic episodes that affected the area. This study foc...
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