Abstract High‐pressure granulites are characterised by the key associations garnet‐clinopyroxene‐plagioclase‐quartz (in basic rocks) and kyanite‐K‐feldspar (metapelites felsic typically orthopyroxene‐free in both bulk compositions. In regional metamorphic areas, two essential varieties exist: a high‐ to ultrahigh‐temperature group representing overprinted eclogites. The type formerly contained high‐temperature ternary feldspar (now mesoperthite) coexisting with kyanite, is associated garnet...

Abstract High‐pressure basic granulites are widely distributed as enclaves and sheet‐like blocks in the Huaian TTG gneiss terrane Sanggan area of Central Zone North China craton. Four stages metamorphic history have been recognised mineral assemblages based on inclusion, exsolution reaction textures integrated with garnet zonation patterns revealed by compositional maps profiles. The P–T conditions for each stage were obtained using thermodynamically experimentally calibrated...

Abstract In-situ U-Th-Pb analyses by ion-microprobe on zircon in intact textural relationships are combined with backscatter and cathodoluminescence imaging trace element to provide evidence for growth episodes of zircon. This approach helps: (a) unravel the polymetamorphic history aluminous migmatitic granitoid gneisses regional contact aureole around Rogaland anorthosite-norite intrusive complex; (b) constrain age M 2 ultrahigh-temperature (UHT) metamorphism subsequent retrograde 3 event....

Research Article| May 01, 2001 Coesite in Himalayan eclogite and implications for models of India-Asia collision P.J. O'Brien; O'Brien 1Bayerisches Geoinstitut, Universität Bayreuth, D-95440 Germany Search other works by this author on: GSW Google Scholar N. Zotov; Zotov R. Law; Law 2Geological Sciences, Virginia Tech, Blacksburg, 24061, USA M.A. Khan; Khan 3Government College, Sargodha, Pakistan M.Q. Jan 4National Centre Excellence Geology, University Peshawar, Geology (2001) 29 (5):...

Pressure–temperature conditions for formation of the peak metamorphic mineral assemblages in phengite‐bearing eclogites from Dabieshan have been assessed through a consideration Fe 2+ –Mg partitioning between garnet–omphacite and garnet–phengite pairs reaction equilibrium celadonite+pyrope+grossular=muscovite+diopside, which incorporates an evaluation extent strongly pressure‐dependent inverse Tschermak's molecule substitution phengites. For latter equilibrium, calibration recommended...

Journal Article Thermobarometry and Geotectonic Significance of High-Pressure Granulites: Examples from the Moldanubian Zone Bohemian Massif in Lower Austria Get access D. A. CARSWELL, CARSWELL 1Department Earth Sciences, University SheffieldBeaumont Building, Brookhill, Sheffield S3 7HF, UK Search for other works by this author on: Oxford Academic Google Scholar P. J. O'BRIEN 2Bayerisches Geoinstitut, Universität BayreuthPostfach 101251, W-8580 Bayreuth, Germany Petrology, Volume 34, Issue...

Abstract The pressures required for diamond and coesite formation far exceed conditions reached by even the deepest present-day orogenic crustal roots. Therefore occurrence of metamorphosed continental crust containing these minerals requires processes other than thickening to have operated in past. Here we report first situ finding coesite, characterized micro-Raman spectroscopy, high-pressure granulites otherwise indistinguishable from found associated with garnet peridotite throughout...

Subduction is the main process that recycles surface material into mantle. Fluids and melts derived by dehydration partial melting reactions of subducted continental crust, a major reservoir volatiles (i.e., H 2 O CO ) incompatible elements, can substantially metasomatize refertilize Here, we investigate glassy inclusions silicate melt origin found in Variscan ultrahigh-pressure eclogites to assess crust contribution mantle metasomatism journey volatiles, carbon particular, deep roots...

Abstract SHRIMP U–Pb ages have been obtained for zircon in granitic gneisses from the aureole of Rogaland anorthosite–norite intrusive complex, both ultrahigh temperature (UHT; >900 °C pigeonite‐in) zone and outside hypersthene‐in isograd. Magmatic metamorphic segments composite were characterised on basis electron backscattered cathodoluminescence images plus trace element analysis. A sample UHT has magmatic cores with an age 1034 ± 7 Ma (2σ, n = 8) 1052 5 (1σ, 1) overgrown by M1 rims...

Research Article| May 01, 2015 Preserved near ultrahigh-pressure melt from continental crust subducted to mantle depths Silvio Ferrero; Ferrero 1Universität Potsdam, Institut für Erd- und Umweltwissenschaften, 14476 Germany2Museum Naturkunde (MfN), Leibniz-Institut Evolutions- Biodiversitätsforschung, 10115 Berlin, Germany Search for other works by this author on: GSW Google Scholar Bernd Wunder; Wunder 3Helmholtz-Zentrum Deutsches GeoForschungsZentrum (GFZ), D-14473 Katarzyna Walczak;...

Abstract The evolution of the crystalline internal zone European Variscides (i.e. Moldanubian and Saxo-Thuringian) is best understood within a framework two distinct subduction stages. An early, pre-Late Devonian (older than 380 Ma), stage recorded in medium-temperature eclogites blueschists derived from low-pressure basaltic gabbroic protoliths now found as minor relics amphibolite facies meta-ophiolite or gneiss-metabasite nappe complexes. A second exhumation event produced further...

Abstract New petrographic evidence and a review of the latest radiometric age data are taken to indicate that formation ultra‐high pressure (UHP) eclogites within Western Gneiss Region Norway probably occurred 400–410 Ma time frame. Thus, this event took place significantly later than previous, widely accepted c. 425 for timing high metamorphism in part Scandinavian Caledonides. Garnet growth under UHP (coesite‐stable) conditions is recognised as discrete, younger following on from earlier...

Granulites of intermediate to felsic composition were investigated from the Góry Sowie (Owl Mts) Massif central Sudetes SW Poland. The strongly deformed granulites are in tectonic contact with ortho- and paragneisses that underwent polyphase deformation metamorphism before late Devonian. metamorphic evolution is best exhibited by once contained primary assemblage ternary feldspar–garnet–clinopyroxene–quartz–kyanite–rutile, which conditions 900–1000°C, 15–20 kbar deduced. A medium-pressure...

Early Tertiary, coesite-bearing eclogites crop out in the internal zones of Indian Plate Kaghan Valley North Pakistan. Field and geochronological data suggest that UHP metamorphism, at c . 46 Ma, accompanied subduction leading edge continental India beneath Kohistan. A new U–Pb rutile age 44.1 ± 1.1 Ma can be interpreted as either a growth or cooling age, given uncertainty closure temperature for Pb, but clearly documents very short-lived metamorphic peak, with occurring between 44 40 Ma....