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Metamorphic eclogites - Crossref

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Last Updated: 06 February 2022

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Glaucophane and barroisite eclogites from the Upper Kaghan nappe: implications for the metamorphic history of the NW Himalaya

In glaucophane eclogite and garnet-omphacite-rutile-rengite in barroisite eclogite, the metamorphic peak assemblage is garnet-omphacite-rutile quartz. White mica may be present either as part of the peak assemblage or as part of a retrogressive phase after kyanite. Amphibole is later than the metamorphic peak assemblage and is barroisite in most cases, but in relatively Fe-rich eclogite, it is glaucophane with significant Na in the A site, Ca, and tetrahedral A1. T = 610 °C and P = 24 kbar from Fe/Mg partition in garnet-omphacite pairs and the garnet-omphacite barometer, as well as the garnet-omphacite barometer, has been estimated at T = 610 30 °C and P = 24 kbar from T = 24 2 kbar from Fe/Mg partition in barroisite eclogites. The eclogite-bearing units of the Upper Kaghan nappe and metamorphic evolution of the Neelum valley just east of the Kaghan valley indicate that the eclogite-bearing units of the Kaghan-Neelum area, which were subjected to high pressure metamorphism in middle Eocene times, have a terrane of regional extent. A comparison of the metamorphic changes of the NW Himalaya's eclogites with that of the granulitized eclogites recently found in the E Himalaya indicates the possibility of a Himalaya-wide eclogitic metamorphism of pre-Miocene age. The major difference between the High Himalayan Crystalline nappes of the NW Himalaya and those of the E Himalaya's remains less in the early phase of their metamorphic evolution than in the different P-T paths they took during exhumation.

Source link: https://doi.org/10.1144/gsl.sp.2000.170.01.22


Oxygen isotope fractionation between rutile and water and geothermometry of metamorphic eclogites

The mechanism of rutile formation is a ‘armourous' reaction in which rutile develops around grains of titanium metal during solution-precipitation processes. Mean fractionation results calculated as 10 3 in the new study are: 6. 600. 27 at 4056 °C 6. 610. 16%' at 304°C 6. 11 0. 1 percent. From 300 °C to 700 °C, A minimum in the calibration curve 10 3 ln versus 10 6 T - 2 + may be represented by the following: 10 3 ln = 10 6 T 2 +. The latest metamorphism of the Tauern eclogites has hit about 450 °C, according to Petrologic results. The measured partitions of 18 O between rutile and quartz indicate temperatures around 550 °C, which were traced back to a earlier metamorphic event.

Source link: https://doi.org/10.1180/minmag.1979.043.327.14


Resolving uncertainties in the application of zircon Th / U and CL gauges to interpret U-Pb ages: a case study of eclogites in polymetamorphic terranes of NW Iberia

When interpreting U-Pb ages, a watertight argument can be used to explain U-Pb ages. Both U-Pb and trace element data were collected for each point. zircon was part of the eclogite facies mineral assemblage at 390 Ma. , according to the synthesis of TE and structural evidence. Our findings show that in challenging orogenic situations and extreme environments, well-known methodologies and geochemical relationships must be used in conjunction with TE data and organizational structures as provenance/process gauges, as shownance/process gauges.

Source link: https://doi.org/10.5194/se-2020-53


Multistage Metamorphic Evolution of Retrograded Eclogites from the Songshugou Complex, Qinling Orogenic Belt, China

Abstract The Qinling Orogenic Belt is one of eastern Asia's most important collision orogens, and it marks the boundary between the North China Craton and South China Craton. The Songshugou complex is the first basic to ultrabasic body to be discovered in the North Qinling Belt, and it has been emplaced as a lens-shaped body at the southern margin of the Qinling Group. A multistage metamorphic history can be gathered in a multistage metamorphic study, garnet amphibolite, augen amphibolite, and well-foliated amphibolite, as well as garnet zoning patterns of key and trace elements, inclusions in garnet, and thermodynamic modeling reveal a multistage metamorphic history. Mineral inclusions and a volatile chemical composition of garnet are indications of this third garnet growth stage, although optically the partially resorbed rim is not identifiable, but mineral inclusions and a inconsistent chemical composition of garnet are indicative of this third garnet growth stage. Detailed data on garnet's distribution patterns show continuous expansion without fail, and they allow us to identify the reactions responsible for garnet growth. Prehnite and pumpellyite, which developed on a late retrograde stage or at a different event under poor P–T conditions, are also present in certain coronae around garnets and symplectites. While the age of garnet core growth remains enigmatic, the eclogite-facies metamorphic event must be attributed to the deep subtraction of the Songshugou complex during the early Paleozoic's. The growth of garnet cores indicates upper amphibolite-facies regional metamorphic overprint triggered by an eclogite-facies event around 500 Ma, which culminated in subsequent regression in replacement of garnet and the emergence of symplectite.

Source link: https://doi.org/10.1093/petrology/egaa007


Tectonometamorphic evolution of the Acatlan Complex eclogites (southern Mexico)

The Acatlan Complex in southern Mexico has been linked to the growth of the Appalachian, Acadian, and Alleghanian orogenies of northeastern North America. CaNa amphibole, garnet + CaNa pyroxene + phengitic mica + quartz zoisite + quartz – caese rutile rutile, rutile. The Ordovician's thermological signatures, thermobarometric measurements, and available radiometric data ages reveal that eclogite-facies metamorphism took place during the Ordovician at temperatures between 560 60°C and pressures between 11 and 15 kbar. The central assemblage calcic pyroxene + calcic amphibole + garnet + epidote + quartz, as well as greenschist facies are represented by the assemblage actinolite + albitic plagioclase + chlorite + chlorite. The Acatlan Complex evolved in a more complicated continental collisional environment, including intraoceanic arcs, than shown in previously proposed models, according to the obtained PT course.

Source link: https://doi.org/10.1139/e02-093

* Please keep in mind that all text is summarized by machine, we do not bear any responsibility, and you should always check original source before taking any actions

* Please keep in mind that all text is summarized by machine, we do not bear any responsibility, and you should always check original source before taking any actions