We conducted a geochemical study of eclogites (40 samples) from a boudin of the Lower Unit of the Maksyutov Complex in the South Urals in order to determine their protolith nature.

2011-07-02

Dome‐margin eclogite zircon retains a widespread record of protolith age (c. 470–450 Ma, the same as host gneiss protolith age), whereas dome‐core eclogite zircon has more scarce preservation of inherited zircon. The kyanite eclogite and one bimineralic eclogite occur with slight positive Eu-anomalies, whereas in the remaining eclogites no indication of plagioclase in the protolith is present. High Ni and Cr contents of some orthopyroxene bearing eclogites indicative that olivine and chromium-spinel were present in the protolith.

2019-05-01 · Identifying eclogite protolith is essential to decipher such process of subduction and collision. However, the origin of YA eclogite is not well known. Since eclogites were likely originated from various types of continental or oceanic rocks in subduction zone, limited geochemical data sometimes lead to the controversial conclusions (e.g. Qilian eclogite.

Uplift of eclogites back to the surface often involves retrograde metamorphism The protolith rock was subjected to eclogite-facies metamorphism at 2.7 to 2.8

Eclogite ( / ˈɛklədʒaɪt /) is a metamorphic rock formed when mafic igneous rock is subjected to high pressure. Eclogite forms at pressures greater than those typical of the crust of the Earth.

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

2 Ga ages, which are broadly com- CONSTRAINTS ON THE ECLOGITE PROTOLITH The Nunatak eclogites exhibit prominent negative Eu anomalies (Fig. DR2) that point toward plagioclase fractionation in a “shallow” magmatic precursor that, in concert with crustal δ18O signatures in garnet (Fig.

[2005] dated their M3 granulite-facies event, but were unable to provide any direct evidence to support this hypothesis. Liu et al. [2007] dated three The magmatic zircon from both the retrograded eclogite and mafic schist yielded protolith ages of 451 ± 3 Ma, which is consistent with the ages of Early Palaeozoic ophiolitic complexes and ocean island sequences in the CMOB reported in previous studies. 2011-07-02 The Gubaoquan eclogite occurs in the Paleozoic Beishan Orogen of NW China. Previously it has been interpreted as a fragment of subducted oceanic crust that was emplaced as a mélange within continental rocks. Contrary to this, we demonstrate that the Gubaoquan eclogite protolith was a Neoproterozoic basic dyke/sill which intruded into Proterozoic continental rocks.
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Geochemical signatures for eclogite protolith from the Maksyutov Complex, South Urals N.I. Volkova*, A.E. Frenkel, V.I. Budanov, G.G. Lepezin Institute of Mineralogy Eclogite. Eclogite: A high P/T metamorphic rock composed of more than 75% vol. garnet (often pyrope or Mg-rich almandine) and omphacite (Na-Ca-Al-Mg clinopyroxene). Both must be present and neither component more than 75% vol.

Subduction-related eclogites are products of their igneous, metamorphic, fluid-rock, and tectonic histories. Eclogite is a rare and important rock because it is formed only by conditions typically found in the mantle or the lowermost part of thickened crust..
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The mafic rocks preserve partially transitional relationships from protolith gabbro to UHP eclogite, as documented by detailed petrological, geochronological, and.

The peak metamorphic condition was estimated as P > 15 kb (probably up to 20 kb) for a minimum temperature of 580°C ( Groppo et al., 2007 ). 2011-12-01 2019-05-01 2016-12-01 Eclogite. Eclogite: A high P/T metamorphic rock composed of more than 75% vol. garnet (often pyrope or Mg-rich almandine) and omphacite (Na-Ca-Al-Mg clinopyroxene).

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Major element contents of the eclogite cores are broadly similar to basalts with the exception of the high Na contents, presumably reflecting a seawater-altered oceanic crust protolith . Retrogression from eclogite to blueschist to greenschist is associated with decreasing SiO 2 and Na 2 O but increasing Al 2 O 3 content ( Figs. 2B, 2D ).

The zircon cores yield an age of 796 ± 13 Ma, which is taken as the protolith formation age of the eclogite, and implies that the NQ terrane may belong to the SCB before it collided with the NCB. The ɛ Hf (t) values vary from −11.3 to 3.2 and corresponding two‐stage Hf model ages are 2402 to 1495 Ma, suggesting the protolith was derived from an enriched mantle. 2006-11-15 · Protolith age of the eclogite Two data points from the SHRIMP dating of the eclogite gave 206 Pb/ 238 U apparent ages of 755 and 768 Ma. These dates are from zircons with dark cores or oscillatory zoning and with Th/U ratios >1. Trace element data suggest that the eclogite protoliths include both enriched and normal mid‐oceanic ridge basalt (E‐MORB and N‐MORB) and also gabbroic cumulates. The blueschists show more variation in protoliths, which include N‐MORB, Oceanic Island Basalt (OIB) and Island Arc Basalt (IAB). Major element contents of the eclogite cores are broadly similar to basalts with the exception of the high Na contents, presumably reflecting a seawater-altered oceanic crust protolith . Retrogression from eclogite to blueschist to greenschist is associated with decreasing SiO 2 and Na 2 O but increasing Al 2 O 3 content ( Figs. 2B, 2D ).

Eclogite (Muenchberg Gneiss Massif; Early Ordovician protolith, about 480 Ma; Late Devonian metamorphism, about 365 Ma; Wissenstein, just south of Stammbach, Frankenwald Forest, Bavaria, southeast-central Germany) 1 (15097930745).jpg 734 × 837; 855 KB.

For example, blueschist and eclogite facies rocks form under low to medium Uplift of eclogites back to the surface often involves retrograde metamorphism The protolith rock was subjected to eclogite-facies metamorphism at 2.7 to 2.8 7 Feb 2015 (1997) Protoliths of the gneisses and mafic rocks in the Hellevik-Flekke area in Sunnfjord, Western. Norway. Norwegian Geological Survey av O Paulsson · 1996 · Citerat av 1 — The metamorphic grade of the complex is generally amphibolite, locally eclogite facies.

tary protolith of the complex is considered to be an eastern margin of the East European platform, which was subducted beneath island arc ( Leech and Ernst, 2000 ). Protolith: Metamorphic: Facies: Eclogite: Common minerals: Omphacite Pyrope Quartz Kyanite Rutile: Eclogite in hand sample.