نتایج جستجو برای: phengite
تعداد نتایج: 84 فیلتر نتایج به سال:
Thallium (Tl) is a highly incompatible element which can be redistributed during various igneous and hydrothermal events such as mineral dehydration low-temperature alteration. Despite the strong influence fluid-rock interactions have on Tl redistribution importance of fluids in subduction-zone volatiles cycling, geochemical behavior high-P/T metamorphism has not yet been quantified. Here we pr...
A comparison was made between single-crystal structure refinements, electron microprobe analyses and octahedral site populations of seven biotite crystals and data obtained previously for coexisting muscovite in peraluminous granites using the same methods. Both micas, from several plutons of Northern Victoria Land (Antarctica) and Sardinia (Italy), show significant octahedral substitutions: bi...
A Cretaceous paleo-accretionary wedge, the Ashin Complex, now exposed along Zagros suture zone in southern Iran, exhibits mafic, metasedimentary and ultramafic lithologies. Field, geochemical petrological observations point to an anomalous high-temperature event that gave rise formation of peritectic (trondhjemitic) melts associated with restitic garnet-bearing amphibolites. Lu-Hf isotopic dati...
Abstract Whiteschists from the Monte Rosa Nappe were examined in field as well with petrographic, geochemical, and isotopic methods to constrain controversial origin of these rocks their Alpine metamorphic context. occur ellipsoidal-shaped, decametric-sized bodies, within a Permian metagranite, consist mainly chloritoid, talc, phengite, quartz. The transition whiteschist metagranite is marked b...
New field observations and petrological data from Early Cretaceous metamorphic rocks in the Central Cordillera of Colombian Andes allowed recognition thermally overprinted high-pressure derived oceanic crust protoliths. The obtained path suggests that evolved blueschist to eclogite facies towards upper amphibolite granulite transitional conditions. Eclogite conditions, better recorded mafic pro...
Abstract The rates and mechanisms by which deeply subducted continental crust was exhumed back to the surface are not well understood, but can be better characterized using multimineral petrochronology. Here, we combine zircon, titanite, apatite U-Pb ages from leucogranite phengite gneiss with a pressure–temperature (P–T) path eclogite provide robust quantitative constraints on cooling exhumati...
The Dinaride Ophiolite Belt formed from the Jurassic part of Neotethys. investigated Ozren ophiolite complex in Bosnia and Herzegovina consists peridotites, plagioclase plagiogranites, troctolites other gabbroic rocks, fewer basalts. Lherzolites harzburgites contain corroded ortho- clinopyroxene1 porphyroclasts enclosed olivine matrix. boundaries between aggregates pyroxene1 spinel1 are infille...
The architecture and pressure-temperature conditions reached by a Cretaceous block-in-matrix serpentinite mélange exposed in the Zagros suture resemble those imaged active Mariana subduction zone. There, large magnitude-earthquakes (M>w9) have never been recorded but smaller events – of poorly-constrained physical origin range M?w3-6 are widespread. Field petro-structural constraints led to fir...
Abstract We performed phase equilibrium experiments on a natural Ca-poor pelite at 3 GPa, 750–1000°C, under moderately oxidizing conditions, simulating the partial melting of such lithologies in subduction zones. Experiments investigated effect sulphur addition equilibria and compositions, with S contents up to ∼ 2.2 wt. %. Run products were characterized for their major trace element contents,...
The composite Albian–Eocene orogenic wedge of the northern part Inner Western Carpathians (IWC) comprises European Variscan basement with Upper Carboniferous–Triassic cover and Jurassic to Cretaceous sedimentary successions a large oceanic–continental Atlantic (Alpine) Tethys basin system. This paper presents an updated evolutionary model for principal structural units (i.e., Fatricum, Tatricum...
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