Rock group, Metamorphic. Metamorphism type, Regional High pressure. High temperature. Metamorphic rock class, Metabasite Metapelite. Protolith

Protolith of the Stak eclogite in the northwestern Himalaya Yui Kouketsu (*) , Kéiko Hattori (**) & Stéphane Guillot (***) (*) Geochemical Research Center, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan.

Norway. Norwegian Geological Survey av O Paulsson · 1996 · Citerat av 1 — The metamorphic grade of the complex is generally amphibolite, locally eclogite facies. The protolith of the underlying Särv Nappes of the av LG Albrecht · 2000 · Citerat av 35 — Calculated pressure-temperature conditions for the eclogite facies stage are 20-27 kbar and 650-750°. Protolith corona-dolerite dykes share the T-MORB Geochemical data and an initial epsilon Nd value of similar to +9 suggest an N-MORB protolith for the eclogite.

printing (Fig. 2a). The protolith is low-K basalt in composition and exhibits geochemical characters of normal-type MORB (N-MORB) afﬁnity (Song et al. 2006).We named itbasaltic eclogite. Inthis eclogite, omphacite is equigranular, relatively small in size and chemically homogeneous; garnet occurs as por-phyroblasts uniformly distributed in 2020-11-16 · Eclogite facies metamorphic rocks formed through subduction and collision processes are common in global orogenic belts 1,2,3,4,5,6,7,8,9,10,11,12 (e.g., Usagaran belt 1, Belomorian Belt 2, Trans The origin and evolution of subduction-related mantle eclogites (SM eclogites) have the following stages (see review in Korolev et al.

The internal structures of zircons in eclogite from Huangzhen have been studied by cathodoluminescence (CL) microscopy. Two growth stages were distinguished: protolith magmatic cores and metamorphic overgrowth rims. These different domains were analyzed for trace elements using LAM-ICP-MS.

Kaalvallei Group II eclogite xenoliths are likely to have formed through crystallization of small-volume melts within conduits in old, enriched subcontinental lithosphere. Oxygen isotope compositions are reported for the first time for the Himalayan metabasites of the Kaghan Valley, Pakistan in this study. The highest metamorphic grades are recorded in the north of the valley, near the India-Asia collision boundary, in the form of high-pressure (HP: Group I) and ultrahigh-pressure (UHP: Group II) eclogites. Analyses from zircon cores in one sample yield scattered 433 to 474 Ma ages, reflecting partial overlap on rims, and constrain the minimum age of eclogite protolith crystallization.

formed at N14 kbar and ~710 °C in the eclogite facies. Bulk-rock geochemistry and field relations indicate that the protoliths of the mafic gneisses were likely

Inthis eclogite, omphacite is equigranular, relatively small in size and chemically homogeneous; garnet occurs as por-phyroblasts uniformly distributed in 2020-11-16 · Eclogite facies metamorphic rocks formed through subduction and collision processes are common in global orogenic belts 1,2,3,4,5,6,7,8,9,10,11,12 (e.g., Usagaran belt 1, Belomorian Belt 2, Trans The origin and evolution of subduction-related mantle eclogites (SM eclogites) have the following stages (see review in Korolev et al. Reference Korolev, Melnik, Li and Skublov 2018): (1) formation of an oceanic crust protolith (i.e. basalts and gabbros), (2) hydrothermal alteration of the oceanic crust by seawater, (3) subduction-related metamorphism, partial melting and metasomatism, (4) long-term residence in the lithospheric mantle with possible mantle metasomatism, (5) interaction with In steady-state subduction zones with high rates of shear heating, the upper parts of the subducting oceanic crust progress through the greenschist → amphibolite → granulite → eclogite facies, whereas lower parts of the subducting oceanic crust progress through the blueschist → eclogite facies.

Zircon U–Pb dating and whole-rock Nd–Sr isotope analyses indicate that eclogite protolith is the paleoceanic basalt that was derived from the depleted mantle by magmatism at about 1.8 to 1.9 Ga but experienced hydrothermal alteration by surface waters. For oceanic crust containing 1-2 wt% H 2 O, dehydration will not begin until the onset of eclogite- or amphibolite-facies metamorphism, depending on the P-T path.
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formation at low pressures, albeit in a scenario where either. Each aluminum oversaturation in the eclogite protolith, which can not be incorporated in garnet and omphacite, crystallized in the eclogite as kyanite (nesosilicate). The protolith rock was subjected to eclogite-facies metamorphism at 2.7 to 2.8 billion years ago, during the early Neoarchean. Uplift and decompression resulted in the formation of some new minerals, which occurred at 1.89 billion years (late Paleoproterozoic). Specimen owned by James Cheshire.

The protoliths of the eclogites have at least two distinct ages, 750–800 and ∼1000 Ma. The protolith age of orthogneiss is about 900–1000 Ma, which may reflect another metamorphic event.
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EVOLUTION OF ECLOGITE FACIES METAMORPHISM IN THE ST. CYR KLIPPE, YUKON-TANANA TERRANE, YUKON, CANADA by Meredith Blair Petrie Ma, while the metatonalite protolith formed at approximately 334 Ma, during the Little Salmon Cycle of the Klinkit phase of Yukon-Tanana arc activity.

1.66 Ga The intrusive protoliths to orogen that hosts eclogite-bearing tectonic units, as. indicating their crystallisation from a protolith with a short crustal residence time. amphibolite – eclogite source, i.e. melting over a range of pressures/depths.

24 Apr 2020 origin of the eclogite protoliths [2,15]. High-Mg olivine (forsterite with #Mg > 90) is often found in mantle peridotite or is enclosed in micro- and

Eclogite appears to be moderately common in portions of the upper mantle, but it occurs in very few places at Based on compositional zoning in garnet and application of diffusion modelling, we propose that eclogite-facies metamorphism of the mafic protolith and its host lithologies occurred at, or near, UHP conditions. The core garnet (I) formed at 650 °C at 8 Myr in the coesite stability field and was partially resorbed during the onset of exhumation. Eclogite genesis might have been by residue formation associated with the dehydration and partial melting of a protolith consisting of variably mixed, subducted ocean floor basalt and sediment. Kaalvallei Group II eclogite xenoliths are likely to have formed through crystallization of small-volume melts within conduits in old, enriched subcontinental lithosphere. Oxygen isotope compositions are reported for the first time for the Himalayan metabasites of the Kaghan Valley, Pakistan in this study. The highest metamorphic grades are recorded in the north of the valley, near the India-Asia collision boundary, in the form of high-pressure (HP: Group I) and ultrahigh-pressure (UHP: Group II) eclogites. Analyses from zircon cores in one sample yield scattered 433 to 474 Ma ages, reflecting partial overlap on rims, and constrain the minimum age of eclogite protolith crystallization.

Eclogite contains no plagioclase although its protolith is full of this mineral.