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Granulite

About: Granulite is a research topic. Over the lifetime, 6763 publications have been published within this topic receiving 268925 citations.


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TL;DR: Pb isotopic compositions for three suites of well-characterized granulite facies xenoliths from a diversity of crustal settings (the Chudleigh and McBride volcanic provinces, Queensland, Australia and the Eifel volcanics, West Germany) are presented in this paper.

212 citations

Journal ArticleDOI
TL;DR: In this paper, the authors used numerical simulations of coupled intergranular and intracrystalline diffusion processes in coronal textures around partially resorbed garnet crystals from the Llano Uplift, U.S.A.
Abstract: Mounting evidence suggests that partial disequilibrium—meaning disequilibrium for some elements, but not for others—may be a common but rarely detected phenomenon during metamorphic mineral growth, even in ordinary prograde reactions that progress to completion. Detailed examination of compositional variations in garnet crystals over a range of metamorphic grade suggests distinctly different scales of equilibration for common elements, with strong temperature dependence. Under lower greenschist-facies conditions, Fe and Mg may equilibrate at hand-sample scale, whereas Mn and Ca may not equilibrate even at millimeter-scale. Although Mn may achieve hand-sample-scale equilibration under upper greenschist-facies conditions, Ca and many trivalent cations (e.g., REEs) may not do so until temperatures exceed those of the middle amphibolite facies. Even in the lower granulite facies, some elements (e.g., Y, Yb) show indications of disequilibrium at sub-centimeter-scales during garnet growth. Analysis and numerical modeling of undisputed disequilibrium textures demonstrate that the most common impediment to equilibration during metamorphism is the sluggishness of intergranular diffusion, the same mechanism known to govern porphyroblast crystallization in many metamorphic environments. Despite this importance to petrology, few quantitative determinations exist of inter-granular diffusion rates under metamorphic conditions. Using numerical simulations of coupled intergranular and intracrystalline diffusion processes in coronal textures around partially resorbed garnet crystals from the Llano Uplift, U.S.A., a very precise and relatively accurate estimate is obtained for the rate of intergranular diffusion of Al in fluid-undersaturated systems. This result and an earlier estimate for fluid-saturated systems provide bracketing values for Al diffusivity during metamorphism.

212 citations

Journal ArticleDOI
TL;DR: In this paper, the authors report field characteristics, petrography, geochemistry and isotopic ages of the Neoarchaean intrusive complex and the Paleoproterozoic metamorphic belt around Quruqtagh in the northern margin of the Tarim Block, NW China.

211 citations

Journal ArticleDOI
TL;DR: Wang et al. as discussed by the authors showed that the Dulan region is a UHP metamorphic terrane, and the peak conditions of the NDB eclogites are P = 2.9-3.2 GPa, and T = 631-687°C.
Abstract: Widespread evidence for ultrahigh-pressure (UHP) metamorphism is reported in the Dulan eclogite-bearing terrane, the North Qaidam–Altun HP–UHP belt, northern Tibet. This includes: (1) coesite and associated UHP mineral inclusions in zircon separates from paragneiss and eclogite (identified by laser Raman spectroscopy); (2) inclusions of quartz pseudomorphs after coesite and polycrystalline K-feldspar + quartz in eclogitic garnet and omphacite; and (3) densely oriented SiO2 lamellae in omphacitic clinopyroxene. These lines of evidence demonstrate that the Dulan region is a UHP metamorphic terrane. In the North Dulan Belt (NDB), eclogites are characterized by the peak assemblage Grt + Omp + Rt + Phn + Coe (pseudomorph) and retrograde symplectites of Cpx + Ab and Hbl + Pl. The peak conditions of the NDB eclogites are P = 2.9–3.2 GPa, and T = 631–687 °C; the eclogite shows a near-isothermal decompression P–T path suggesting a fast exhumation. In the South Dulan Belt (SDB), three metamorphic stages are recognized in eclogites: (1) a peak eclogite facies stage with the assemblage Grt + Omp + Ky + Rt + Phn at P = 2.9–3.3 GPa and T = 729–746 °C; (2) a high-pressure granulite facies stage with Grt + Cpx (Jd < 30) + Pl (An24–29) + Scp at P = 1.9–2.0 GPa, T = 873–948 °C; and (3) an amphibolite facies stage with the assemblage Hbl + Pl + Ep/Czo at P = 0.7–0.9 GPa and T = 660–695 °C. The clockwise P–T path of the SDB eclogites is different from the near-isothermal decompression P–T path from the NDB eclogites, which suggests that the SDB was exhumed to a stable crustal depth at a slower rate. In essence these two sub-belts formed in different tectonic settings; they both subducted to mantle depths of around 100 km, but were exhumed to the Earth's surface separately along different paths. This UHP terrane plays an important role in understanding continental collision in north-western China.

211 citations

Journal ArticleDOI
TL;DR: In this paper, an oscillatory zircon 58 Ma (Th/U = 0·52; secondary ion mass spectrometry data), records fluid infiltration and coeval eclogitization in the crust.
Abstract: distance around rutile, and locally these zircons show a prismatic The Proterozoic Lindas Nappe, part of the Caledonides of western overgrowth. A specific low-Th zircon growth event is related to Norway, was affected by penetrative Sveconorwegian granulite-facies eclogite-facies forming reactions, involving breakdown of a twometamorphism, followed by a fluid-driven eclogiteand amphibolitepyroxene + garnet + plagioclase + ilmenite assemblage to form facies Caledonian overprint, spatially restricted along fractures and a garnet + omphacite + rutile assemblage in the presence of a shear zones. In mafic granulites and amphibolites, a luminescent fluid. The low Th content of this zircon probably stems from the anhedral zircon overgrowth, which gives an average age of 924 ± coeval precipitation of clinozoisite. This oscillatory zoned zircon 58 Ma (Th/U = 0·52; secondary ion mass spectrometry data), records fluid infiltration and coeval eclogitization in the crust. surrounds a magmatic zoned core with an age of 952 ± 32 Ma (Th/U = 1·27). In the granulites, a continuous rim of zircon or a discontinuous corona of >10 m rounded to flat zircon crystals is observed at the outer margin of ilmenite grains. Baddeleyite and

211 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023126
2022301
2021177
2020203
2019148
2018142