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.

Alex Strekeisen - I vetrini della mia fantasia. Blueschist Blueschist is a regional metamorphic rock formed under high-pressure (HP) low-temperature (LT) conditions. It is formed in the subduction zone environment with low geothermal gradients (4-14°C km-1) and is characterized by the presence of HP/LT index minerals like glaucophane, lawsonite, aragonite, jadeite, and deerite (Fig.1).

Eclogite is an attractive, uncommon, crystalline-textured, very high-grade metamorphic rock. It is dominated by green & red minerals. The red is pyrope or almandine garnet. The green is omphacite pyroxene. Eclogite appears to be moderately common in portions of the upper mantle, but it occurs in very few places at the Earth's surface. Contrary to this, we demonstrate that the Gubaoquan eclogite protolith was a Neoproterozoic basic dyke/sill which intruded into Proterozoic continental rocks.

2011-12-01 Urals in order to determine their protolith nature. The eclogites have major element compositions corresponding to quartz-bearing 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. Eclogite never contains plagioclase.

The protoliths of eclogites are igneous rocks with a basaltic composition (basalt, diabase, gabbro). The lack of relatively light-weight plagioclase is the reason why it is so dense compared to its protoliths.

Geochemistry of eclogite- and blueschist-facies rocks from the bantimala complex, south sulawesi, indonesia: Protolith origin and tectonic setting Citation Maulana, A, Christy, A, IMAI, A et al 2013, 'Geochemistry of eclogite- and blueschist-facies rocks from the bantimala complex, south sulawesi, indonesia: Protolith origin and tectonic setting', The Island Arc, vol. 22, no. 4, pp.

The basic blocks represented by the protolith of the eclogites were most likely scraped from the basement of a continental arc by basal erosion during the subduction of the South Tianshan Ocean in Late Paleozoic.

Rutile, kyanite, and quartz are typically present. 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.

This eclogite body may once have been situated 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. 2014-12-01 2011-07-02 protolith age of the mafic eclogites. [6] Inspiteofthelimitedandcontradictory dataavailable, the Ama Drime granulitized eclogites are crucial for recon-structing the tectonic history of the central Himalayan oro-gen. Not only do they potentially record early subduction of … Retrograde eclogite (7.8 cm across at its widest) from the Belomorian Complex (Belomorian Eclogite Province) near Polarnie Zory, Shirokaya Salma District, Kola Peninsula, Baltic Shield/Fennoscandian Shield, far-northwestern Russia. The protolith rock was subjected to eclogite-facies metamorphism at 2.7 to 2.8 billion years ago, during the early Neoarchean.
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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. The protolith to the eclogite is believed to be a Fe- and Ti-rich gabbro of Pro-terozoic age. Transformation into eclogite is related to Cale-donian high-pressure metamorphism at ca. 400 Ma. During this process, ilmenite in the gabbro protolith was replaced by rutile. The eclogite body is subdivided into a leuco-eclogite and a ferro-eclogite 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.

Major element compositions confirm the basaltic nature of the protolith. Trace element abundances normalized to the primitive mantle show almost flat patterns at ten times the primitive mantle 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.
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Our results suggest that the MORB-like protolith of the xenoliths was metasomatized by a fluid equilibrated with sediment in the fore-arc region of a subduction

Transformation into eclogite is related to Cale-donian high-pressure metamorphism at ca. 400 Ma. During this process, ilmenite in the gabbro protolith was replaced by rutile. The eclogite body is subdivided into a leuco-eclogite and a ferro-eclogite 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.