A metamorphic facies is a set of mineral assemblages in metamorphic rocks formed under similar pressures and temperatures. Orthopyroxene‐bearing, mafic migmatites at Cone Peak, California: evidence for the formation of migmatitic granulites by anatexis in an open system. 2010). These early Mesoproterozoic tectonic fabrics and metamorphic assemblages were cut at c. 1480–1450 Ma by newly formed and reactivated crustal-scale shear zones (Swain et … Santosh & Kusky 2010; Santosh alet. In view of this, a feasible explanation for the inferred stability of the supercontinent during the early Palaeoproterozoic and for the scarcity of subduction events along its margins, may lie in the assumption of intensive recycling of juvenile oceanic and young arc-related crust within the oceanic hemisphere (cf. It has been regarded as consisting of three tectonic events and dates from ∼1850 to ∼1690 Ma. High-pressure partial melting and melt loss in felsic granulites in the Kutná Hora complex, Bohemian Massif (Czech Republic). The model endorses that the EGMB–south represents a fraction of an exotic terrane that was transferred to proto-India in the late Paleoproterozoic (1.68–1.6 Ga). The plume-related riftogenic and spreading processes within the continental areas can be attributed to “weak attempts” to disrupt the supercontinent (Mints, 1998). A.B. Although the real reasons for the different evolution of the belts remain unknown, it is clear that this difference played a fundamental role in crustal evolution. Skip to main content Accessibility help We use cookies to distinguish you from other users and to provide you with a better experience on our websites. An overview of metamorphism in relation to tectonic regimes: The 90 Ma Kigluaik pluton forms the core of a granulite facies gneiss dome and is Silica-undersaturated spinel granulites in the Daqingshan complex of the Khondalite Belt, North China Craton: Petrology and quantitative P–T–X constraints. 4.4b). The thermal pulse recorded at c. 1600 Ma in the EGMB-south is similar to the reworking of the NRBF in East Antarctica and may indicate a connection involving the EGMB-south and Napier-Rayner complex at this time (Bose, Dunkley, Dasgupta, Das, & Arim, 2011). This proposal is supported by the recently obtained U–Pb zircon data from the EGMB-south, which preserves a record of a prolonged accretionary process that started in the arc-continent collision and culminated in the continent–continent collision (Pacific-type) during c. 1850–1600 Ma (Vijaya Kumar, Ernst, Leelanandam, Wooden, & Groves, 2009). When water activity is low, pervasive partial (dry) melting will occur at much higher temperatures and hydrous minerals (muscovite, biotite, and amphibole) may decompose to anhydrous ones by local dehydration melting. We use cookies to help provide and enhance our service and tailor content and ads. If both chlorine and CO2 contents are high, then it is likely that immiscible CO2-rich and chlorine-rich fluids would coexist at high P and T (Duan et al., 1995; Schmidt and Bodnar, 2000), consistent with fluid inclusion evidence for multi-phase granulite facies fluids (Touret, 1985; Crawford and Hollister, 1986). medium-pressure granulite-facies metamorphism in the southern Nawa Domain (Cutts et al. Gansser (1983) reported isolated exposures of Precambrian to Mesozoic sedimentaries over the Thimphu Group/HHC/Great Himalayan zone as a remnant of the Tethyan Himalayan sequence. 8.3D). ... granulite facies of high-pressure influences during A similar approach was applied to the description and interpretation of the granulite-gneiss complexes of the Grenville-Sveconorwegian … The metapelite-dominated schist horizon overlying the Sure Formation is named the Naspe Formation (Paro Formation of Gansser, 1983), which consists of a thick interlayered sequence of kyanite–staurolite–garnet–mica schist, commonly graphitic, along with dolomite (Golani, 1995). Considering the worldwide decrease of magmatic activity from c. 2.45 to 2.2 Ga, Condie (1994b) argued that deep-seated heat generation processes in the Earth could not have been significantly lower during that period. The leucogranites intruded the country rocks, which were already heated past the second sillimanite isograds and were deformed penetratively. The proof of the presence of a single continuous belt of rocks also comes from the occurrences of the trails of the coevally metamorphosed Archaean granite-greenstone belt rocks showing a metamorphic state compatible with the enclosing granulite bodies along with the Peninsular Gneiss, meta-basaltic dykes of different generations, and their granulitic equivalents well within the massifs of Biligirirangan, Coorg, and Nilgiri Hills in the south (Rama Rao, 1940; Janardhan, 1983). The processes that control leucosome compositions in metasedimentary granulites: perspectives from the Southern Marginal Zone migmatites, Limpopo Belt, South Africa. Fluid-rock interaction during high-grade metamorphism: Instructive examples from the Southern Marginal Zone of the Limpopo Complex, South Africa. time and in different tectonic settings? A. Feenstra, G. Franz, in Reference Module in Earth Systems and Environmental Sciences, 2015. The later stage (c. 1040–1020 Ma) involved widespread, dominantly upper amphibolite facies metamorphism within and beneath the duplex. The latest, most widespread and intense event at c.1150 Ma gave rise to low-P granulites which record an anticlockwise P-T path and were accompanied by gneissic granite and charnockite. In several outcrops especially in the northern part, south of the east–west trending ‘isograd line’, the charnockite occurs either in the form of small lenses or as diffused stains of charnockitic mass described as ‘patchy charnockite’ within the intensely deformed tonalite-trondhjemite-granodiorite gneisses (Fig. Large‐scale fluid infiltration, metasomatism and re‐equilibration of Archaean basement granulites during Palaeoproterozoic thrust belt construction, Ungava Orogen, Canada. However, the terrane shows sporadic occurrence of granulite, tectonic slices of ophiolite, blue schist and basement The formation of staurolite and the breakdown of chloritoid are generally considered to reflect the greenschist–amphibolite facies transition in pelitic rocks. Metamorphism probably took place in the deep parts of a Jurassic–Early Cretaceous accretionary wedge. In metapelites, staurolite-bearing assemblages gradually replace chloritoid-bearing assemblages. 4.3), banded iron formation, calc-silicate rocks, quartzites, and amphibolites in the southern part of the Dharwar Protocontinent. The rocks in NGB were metamorphosed to granulite facies conditions during Neoarchean to Palaeoproterozoic, with relatively high-pressure (HP) (~14 kbar) metamorphism occurring during the early Neoproterozoic (Peucat, Mahabaleshwar, & Jayananda, 1993). Trace element geochemistry and tectonic setting characterization of granulite facies rocks from southwest Obudu Plateau, southeastern Nigeria.
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