U-Pb datering av zirkon från migmatitisk gnejs i Delsjöområdet

Mineral Ages and P-T Conditions of Late Paleozoic High

The lack of relatively light-weight plagioclase is the reason why it is so dense compared to its protoliths. The eclogite unit occurs in the LHS below the MCT, and the protolith is considered to be 110–88-Ma-old (cretaceous volcanics in the LHS). 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 ). 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. An unusually dense rock, eclogite can play an important role in driving convection within the solid Earth.

Eclogite protolith

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 Lastly, analysis of Sm–Nd isotopes from the protoliths to the high-P rocks at Port Macquarie are used to identify the affinities of the metamorphic precursors. These Typical mineral assemblages of the eclogites are garnet + omphacite + mid- ocean ridge basalt affinities (MORB) with at least one protolith being a cumulate. The mafic rocks preserve partially transitional relationships from protolith gabbro to UHP eclogite, as documented by detailed petrological, geochronological, and. SHRIMP-RG zircon dating shows that the protolith of the eclogites formed within the Yukon-Tanana terrane during early, continental arc activity, between 364 470–450 Ma, the same as host gneiss protolith age), whereas dome‐core eclogite zircon has more scarce preservation of inherited zircon. Possible explanations than an intraplate or OIb setting for the protoliths of the eclogites.

The assemblage is typical of what is formed in conditions corresponding to an area on the two dimensional graph of temperature vs.

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2). The major protolith of the soils in this portion of coastal Maine is glacial till. Marine and lacustrine sediments can be locally important.

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The eclogite in the Flem Gabbro from Flemsøya in the Western Gneiss Region (WGR), Norway, is exceptional due to its peculiar mineral assemblage of olivine and orthopyroxene, which were inherited from an olivine gabbro protolith [8,33]. 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.
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[2007] inferred that the 13–14 Ma ages of Rolfo et al. [2005] dated their M3 granulite-facies event, but were unable to provide any direct evidence to support this hypothesis.

The lack of relatively light-weight plagioclase is the reason why it is so dense compared to its protoliths. 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.. Eclogites are helpful in elucidating patterns and processes of plate tectonics because many represent the crustal rocks that were subducted to depths in excess of 35 km and then returned to the surface. The eclogite unit occurs in the LHS below the MCT, and the protolith is considered to be 110–88-Ma-old (cretaceous volcanics in the LHS).
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Qualitative and quantitative petrography of meta - Bachelor

The eclogite unit occurs in the LHS below the MCT, and the protolith is considered to be 110–88-Ma-old (cretaceous volcanics in the LHS).