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).

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). 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 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).

Island Arc, … 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. Eclogite, any member of a small group of igneous and metamorphic rocks whose composition is similar to that of basalt. Eclogites consist primarily of green pyroxene (omphacite) and red garnet (pyrope), with small amounts of various other stable minerals—e.g., rutile. They are formed when volcanic 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.

The variability of δ18O in garnet among 41 xenoliths, shows a bi-modal distribution with median values at 3.57 ‰ and 5.68 ‰ and strong correlation (r = 0.96) between garnet and omphacite. The δ18O values and the reconstructed whole-rock trace element compositions indicate an oceanic crustal protolith for mantle eclogite xenoliths.

Geochemistry of eclogite- and blueschist-facies rocks from the Bantimala Complex, South Sulawesi, Indonesia: Protolith origin and tectonic setting December 2013 Island Arc 22(4) Geochemistry of eclogite- and blueschist-facies rocks from the Bantimala Complex, South Sulawesi, Indonesia: Protolith origin and tectonic setting ADI MAULANA,1,2,3*ANDREW G. CHRISTY,1,4 DAVID J. ELLIS,1 AKIRA IMAI,5 AND KOICHIRO WATANABE3 1Research School of Earth Sciences, Australian National University, Canberra ACT 0200, Australia, 2Department The variability of δ18O in garnet among 41 xenoliths, shows a bi-modal distribution with median values at 3.57 ‰ and 5.68 ‰ and strong correlation (r = 0.96) between garnet and omphacite. The δ18O values and the reconstructed whole-rock trace element compositions indicate an oceanic crustal protolith for mantle eclogite xenoliths. 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.

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 (Fig. 2).

The lack of relatively light-weight plagioclase is the reason why it is so dense compared to its protoliths. Eclogite (/ ˈɛklədʒaɪt /) is a metamorphic rock formed when mafic igneous rock is subjected to high pressure.

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. 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 .
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The whole-rock trace element composition is consistent with a pyroxenitic protolith. Eclogites that contain coesite, kyanite and corundum (coe-ky-cor) are under eclogite-facies metamorphism and thereafter variably affected by retrograde processes.

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. eclogite Sm–Nd/WR igneous formation of eclogite protolith Stosch & Lugmair (1990) Weissenstein (SW MM) 395–380 Ma eclogite Sm–Nd; Rb–Sr eclogite metamorphism Stosch & Lugmair (1990) Weissenstein area 379 ± 12 Ma eclogite Rb–Sr/Hbl, phengite post-eclogite Gebauer & Grünenfelder (1979) K–Ar Hangendserie The variability of δ18O in garnet among 41 xenoliths, shows a bi-modal distribution with median values at 3.57 ‰ and 5.68 ‰ and strong correlation (r = 0.96) between garnet and omphacite.
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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. Rutile, kyanite, and quartz are typically present.

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.

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 ).

How could you test if you are right other than asking Megan)? 2. 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.

10 th International Kimberlite Conference, Bangalore - 2012. 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). (a) Zircon grains from mantle eclogite xenolith sample 106/505 (G3-12) from the V. Grib kimberlites, Arkhangelsk province (modified after Skublov et al. Reference Skublov, Shchukina, Guseva, Mal’kovets and Golovin 2011 and Shchukina et al. Reference Shchukina, Agashev and Zedgenizov 2018; note that this sample is labelled as 106/505 and G3-12 in the first and second publications on this 2020-11-16 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. eclogite protolith and the hostJericho kimberlite, both the secondary isochron age and the c.2·2 Ga Stacey^Kramers model age are con-sistent with Paleoproterozoic protolith oceanic crust formation. Eclogite xenoliths and eclogitic diamond inclusions from the Slave craton almost exclusively yield c.