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Gregor Markl - One of the best experts on this subject based on the ideXlab platform.
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Formation of Kyanite–quartz veins of the Alpe Sponda, Central Alps, Switzerland: implications for Al transport during regional metamorphism
Contributions to Mineralogy and Petrology, 2008Co-Authors: Thorsten Beitter, Thomas Wagner, Gregor MarklAbstract:In this study, we have investigated the formation of quartz–Kyanite veins of the Alpe Sponda, Central Alps, Switzerland. We have integrated field observations, fluid inclusion and stable isotope data and combined this with numerical geochemical modeling to constrain the chemical processes of aluminum transport and deposition. The estimated P–T conditions of the quartz–Kyanite veins, based on conventional geothermometry (garnet–biotite, white mica solvus and quartz–Kyanite oxygen isotope thermometry) and fluid inclusion data, are 550 ± 30°C at 5.0 ± 0.5 kbar. Geochemical modeling involved construction of aqueous species predominance diagrams, calculation of Kyanite and quartz solubility, and reaction–path simulations. The results of the modeling demonstrate that (1) for the given chemical composition of the vein-forming fluids mixed Al–Si aqueous species are dominant in transporting Al, and that (2) fluid cooling along a small temperature gradient coupled with a pH decrease is able to explain the precipitation of the quartz–Kyanite assemblages in the proportions that are observed in the Alpe Sponda veins. We conclude that sufficient amounts of Al can be transported in typical medium- to high-grade regional metamorphic fluids and that immobile behavior of Al is not very likely in advection–dominanted fluid–rock systems in the upper and middle crust.
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formation of Kyanite quartz veins of the alpe sponda central alps switzerland implications for al transport during regional metamorphism
Contributions to Mineralogy and Petrology, 2008Co-Authors: Thorsten Beitter, Thomas Wagner, Gregor MarklAbstract:In this study, we have investigated the forma- tion of quartz-Kyanite veins of the Alpe Sponda, Central Alps, Switzerland. We have integrated field observations, fluid inclusion and stable isotope data and combined this with numerical geochemical modeling to constrain the chemical processes of aluminum transport and deposition. The estimated P-T conditions of the quartz-Kyanite veins, based on conventional geothermometry (garnet-biotite, white mica solvus and quartz-Kyanite oxygen isotope thermometry) and fluid inclusion data, are 550 ± 30 Ca t 5.0 ± 0.5 kbar. Geochemical modeling involved con- struction of aqueous species predominance diagrams, calculation of Kyanite and quartz solubility, and reaction- path simulations. The results of the modeling demonstrate that (1) for the given chemical composition of the vein- forming fluids mixed Al-Si aqueous species are dominant in transporting Al, and that (2) fluid cooling along a small temperature gradient coupled with a pH decrease is able to explain the precipitation of the quartz-Kyanite assemblages in the proportions that are observed in the Alpe Sponda veins. We conclude that sufficient amounts of Al can be transported in typical medium- to high-grade regional metamorphic fluids and that immobile behavior of Al is not very likely in advection-dominanted fluid-rock systems in the upper and middle crust.
Thorsten Beitter - One of the best experts on this subject based on the ideXlab platform.
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Formation of Kyanite–quartz veins of the Alpe Sponda, Central Alps, Switzerland: implications for Al transport during regional metamorphism
Contributions to Mineralogy and Petrology, 2008Co-Authors: Thorsten Beitter, Thomas Wagner, Gregor MarklAbstract:In this study, we have investigated the formation of quartz–Kyanite veins of the Alpe Sponda, Central Alps, Switzerland. We have integrated field observations, fluid inclusion and stable isotope data and combined this with numerical geochemical modeling to constrain the chemical processes of aluminum transport and deposition. The estimated P–T conditions of the quartz–Kyanite veins, based on conventional geothermometry (garnet–biotite, white mica solvus and quartz–Kyanite oxygen isotope thermometry) and fluid inclusion data, are 550 ± 30°C at 5.0 ± 0.5 kbar. Geochemical modeling involved construction of aqueous species predominance diagrams, calculation of Kyanite and quartz solubility, and reaction–path simulations. The results of the modeling demonstrate that (1) for the given chemical composition of the vein-forming fluids mixed Al–Si aqueous species are dominant in transporting Al, and that (2) fluid cooling along a small temperature gradient coupled with a pH decrease is able to explain the precipitation of the quartz–Kyanite assemblages in the proportions that are observed in the Alpe Sponda veins. We conclude that sufficient amounts of Al can be transported in typical medium- to high-grade regional metamorphic fluids and that immobile behavior of Al is not very likely in advection–dominanted fluid–rock systems in the upper and middle crust.
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formation of Kyanite quartz veins of the alpe sponda central alps switzerland implications for al transport during regional metamorphism
Contributions to Mineralogy and Petrology, 2008Co-Authors: Thorsten Beitter, Thomas Wagner, Gregor MarklAbstract:In this study, we have investigated the forma- tion of quartz-Kyanite veins of the Alpe Sponda, Central Alps, Switzerland. We have integrated field observations, fluid inclusion and stable isotope data and combined this with numerical geochemical modeling to constrain the chemical processes of aluminum transport and deposition. The estimated P-T conditions of the quartz-Kyanite veins, based on conventional geothermometry (garnet-biotite, white mica solvus and quartz-Kyanite oxygen isotope thermometry) and fluid inclusion data, are 550 ± 30 Ca t 5.0 ± 0.5 kbar. Geochemical modeling involved con- struction of aqueous species predominance diagrams, calculation of Kyanite and quartz solubility, and reaction- path simulations. The results of the modeling demonstrate that (1) for the given chemical composition of the vein- forming fluids mixed Al-Si aqueous species are dominant in transporting Al, and that (2) fluid cooling along a small temperature gradient coupled with a pH decrease is able to explain the precipitation of the quartz-Kyanite assemblages in the proportions that are observed in the Alpe Sponda veins. We conclude that sufficient amounts of Al can be transported in typical medium- to high-grade regional metamorphic fluids and that immobile behavior of Al is not very likely in advection-dominanted fluid-rock systems in the upper and middle crust.
J G Liou - One of the best experts on this subject based on the ideXlab platform.
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petrological and geochronological constraints on the origin of hp and uhp Kyanite quartzites from the sulu orogen eastern china
Journal of Asian Earth Sciences, 2011Co-Authors: Wei Wang, Zeming Zhang, Feng Liu, Xin Dong, J G LiouAbstract:Abstract Kyanite (Ky)-quartzites occur in both the high-pressure (HP) and ultrahigh-pressure (UHP) metamorphic belts in the southern Sulu orogen. The HP Ky-quartzites consist of quartz, Kyanite and minor rutile with or without topaz and phengite, whereas those from the UHP unit consist of quartz, Kyanite, phengite and rutile. The HP Ky-quartzites are characterized by high Al2O3 (up to 32.9 wt.%) and low SiO2 (down to 60.4 wt.%) with very low other oxides contents (
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Kyanite anthophyllite schist and southwest extension of the dabie mountains ultrahigh to high pressure belt
Island Arc, 1995Co-Authors: J G LiouAbstract:Kyanite-anthophyllite schist preserves the first record of high pressure in the amphibolite-facies unit of the SW Dabie Mountains, whereas ultrahigh- and high-pressure (UHP and HP) metamorphism has been well documented by the occurrence of coesite, diamond and mafic eclogite in the SE Dabie Mountains. Textural evidence indicates that minerals of the Kyanite-anthophyllite schist formed mainly in two stages: (i) garnet + Kyanite + antho-phyllite + rutile formed at pressure in excess of 1.2 GPa at T < 650°C; (ii) cordierite±staurolite formed by reaction of anthophyllite + Kyanite at P < 0.5 GPa, T∼530°C. Plagioclase and ilmenite replaced garnet and rutile respectively during decompression. In a still later stage, secondary biotite recrystallized, accompanied by sillimanite replacing Kyanite, and spinel replacing staurolite. The P-T information suggests that the amphibolite unit in the SW Dabie Mountains is part of the Triassic collision belt between the Sino-Korean and Yangtze cratons. The P-T paths of the UHP eclogite in the eastern Dabie Mountains and the HP Kyanite-anthophyllite schist in the SW Dabie Mountains show similar decompression and equivalent late stage Barrovian-style metamorphism. Emplacement of voluminous granitoid at middle crustal levels between 134–118 Ma contributed to the development of the Barrovian-type metamorphism in the Dabie Mountains.
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petrology of ultrahigh pressure rocks from the southern su lu region eastern china
Journal of Metamorphic Geology, 1995Co-Authors: R Y Zhang, Takao Hirajima, Shohei Banno, Bolin Cong, J G LiouAbstract:Abstract In the Su-Lu ultrahigh-P terrane, eastern China, many coesite-bearing eclogite pods and layers within biotite gneiss occur together with interlayered metasediments now represented by garnet-quartz-jadeite rock and Kyanite quartzite. In addition to garnet + omphacite + rutile + coesite, other peak-stage minerals in some eclogites include Kyanite, phengite, epidote, zoisite, talc, nyboite and high-Al titanite. The garnet-quartz-jadeite rock and Kyanite quartzite contain jadeite + quartz + garnet + rutile ± zoisite ± apatite and quartz + Kyanite + garnet + epidote + phengite + rutile ± omphacite assemblages, respectively. Coesite and quartz pseudomorphs after coesite occur as inclusions in garnet, omphacite, jadeite, Kyanite and epidote from both eclogites and metasediments. Study of major elements indicates that the protolith of the garnet-quartz jadeite rock and the Kyanite quartzite was supracrustal sediments. Most eclogites have basaltic composition; some have experienced variable ‘crustal’contamination or metasomatism, and others may have had a basaltic tuff or pyroclastic rock protolith. The Su-Lu ultrahigh-P rocks have been subjected to multi-stage recrystallization and exhibit a clockwise P-T path. Inclusion assemblages within garnet record a pre-eclogite epidote amphibolite facies metamorphic event. Ultrahigh-P peak metamorphism took place at 700–890° C and P>28 kbar at c. 210–230 Ma. The symplectitic assemblage plagioclase + hornblende ± epidote ± biotite + titanite implies amphibolite facies retrogressive metamorphism during exhumation at c. 180–200 Ma. Metasedimentary and metamafic lithologies have similar P-T paths. Several lines of evidence indicate that the supracrustal rocks were subducted to mantle depths and experienced in-situ ultrahigh-P metamorphism during the Triassic collision between the Sino-Korean and Yangtze cratons.
Thomas Wagner - One of the best experts on this subject based on the ideXlab platform.
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Formation of Kyanite–quartz veins of the Alpe Sponda, Central Alps, Switzerland: implications for Al transport during regional metamorphism
Contributions to Mineralogy and Petrology, 2008Co-Authors: Thorsten Beitter, Thomas Wagner, Gregor MarklAbstract:In this study, we have investigated the formation of quartz–Kyanite veins of the Alpe Sponda, Central Alps, Switzerland. We have integrated field observations, fluid inclusion and stable isotope data and combined this with numerical geochemical modeling to constrain the chemical processes of aluminum transport and deposition. The estimated P–T conditions of the quartz–Kyanite veins, based on conventional geothermometry (garnet–biotite, white mica solvus and quartz–Kyanite oxygen isotope thermometry) and fluid inclusion data, are 550 ± 30°C at 5.0 ± 0.5 kbar. Geochemical modeling involved construction of aqueous species predominance diagrams, calculation of Kyanite and quartz solubility, and reaction–path simulations. The results of the modeling demonstrate that (1) for the given chemical composition of the vein-forming fluids mixed Al–Si aqueous species are dominant in transporting Al, and that (2) fluid cooling along a small temperature gradient coupled with a pH decrease is able to explain the precipitation of the quartz–Kyanite assemblages in the proportions that are observed in the Alpe Sponda veins. We conclude that sufficient amounts of Al can be transported in typical medium- to high-grade regional metamorphic fluids and that immobile behavior of Al is not very likely in advection–dominanted fluid–rock systems in the upper and middle crust.
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formation of Kyanite quartz veins of the alpe sponda central alps switzerland implications for al transport during regional metamorphism
Contributions to Mineralogy and Petrology, 2008Co-Authors: Thorsten Beitter, Thomas Wagner, Gregor MarklAbstract:In this study, we have investigated the forma- tion of quartz-Kyanite veins of the Alpe Sponda, Central Alps, Switzerland. We have integrated field observations, fluid inclusion and stable isotope data and combined this with numerical geochemical modeling to constrain the chemical processes of aluminum transport and deposition. The estimated P-T conditions of the quartz-Kyanite veins, based on conventional geothermometry (garnet-biotite, white mica solvus and quartz-Kyanite oxygen isotope thermometry) and fluid inclusion data, are 550 ± 30 Ca t 5.0 ± 0.5 kbar. Geochemical modeling involved con- struction of aqueous species predominance diagrams, calculation of Kyanite and quartz solubility, and reaction- path simulations. The results of the modeling demonstrate that (1) for the given chemical composition of the vein- forming fluids mixed Al-Si aqueous species are dominant in transporting Al, and that (2) fluid cooling along a small temperature gradient coupled with a pH decrease is able to explain the precipitation of the quartz-Kyanite assemblages in the proportions that are observed in the Alpe Sponda veins. We conclude that sufficient amounts of Al can be transported in typical medium- to high-grade regional metamorphic fluids and that immobile behavior of Al is not very likely in advection-dominanted fluid-rock systems in the upper and middle crust.
Jan C M De Hoog - One of the best experts on this subject based on the ideXlab platform.
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phase relations during peak metamorphism and decompression of the uhp Kyanite eclogites pohorje mountains eastern alps slovenia
Lithos, 2012Co-Authors: Mirijam Vrabec, Marian Janak, Nikolaus Froitzheim, Jan C M De HoogAbstract:Abstract Phase relations among the mineral assemblages of UHP Kyanite eclogite were investigated in the Pohorje Mountains of the Eastern Alps. Ultrahigh-pressure metamorphism resulted from intracontinental subduction during the Cretaceous (ca. 92 Ma). Kyanite-bearing eclogites are associated with meta-ultramafic rocks including UHP garnet peridotites and are embedded in metapelitic gneisses and micaschists. The Kyanite eclogites contain a peak metamorphic assemblage of garnet, omphacite, Kyanite and phengite. Pyrope-rich garnet is unzoned and almost free of inclusions. The non-stoichiometric supersilicic omphacite contains up to 5 mol% of Ca-Eskola molecule. Breakdown of omphacite during decompression resulted in exsolution of oriented rods of silica. Phengite contains up to 3.5 Si a.p.f.u. Polycrystalline quartz inclusions in peak-pressure minerals – garnet, omphacite and Kyanite – are surrounded by radial fractures diagnostic of the former presence of coesite. Peak-pressure minerals are replaced by symplectites of diopside + plagioclase + amphibole after omphacite, plagioclase + biotite after phengite and sapphirine + corundum + spinel + anorthite after Kyanite. Sapphirine has composition close to (Mg, Fe) 12.4 Al 38.9 Si 4.5 O 80 in average, which is amongst the most aluminous yet reported. Peak metamorphic conditions were constrained from calculated phase equilibria in the NKCFMASH system with the fixed bulk-rock composition, and conventional geothermobarometry. This approach led to consistent results, the calculated peak P–T conditions of 3.0–3.7 GPa and 710–940 °C, in the stability field of coesite and the same range as metamorphic conditions recorded by the associated garnet peridotites. This implies that eclogites and their host rocks were subducted to depths of about 100 km. The relatively high temperature at peak pressure, compared to UHP rocks of Tertiary age in the Western Alps where mostly oceanic crust was subducted, probably resulted from radiogenic heat production by subducting continental crust, in the intra-continental setting of the Cretaceous subduction zone in the Eastern Alps.
