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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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Journal ArticleDOI
TL;DR: In this paper, a two-stage retrograde granulite metamorphism of lower-crustal and upper-mantle rocks path of the Malenco granulites separated by >50 My suggests that the magmatic crystallization of the gabbro was outlasted by ductile Permian extension and Jurassic rifting are two independent tectonic deformation.
Abstract: ago during Early Permian lithospheric extension The intrusion rocks Estimated uplift rates of 1‐2 mm/year indicate a 15‐30 My took place along the crust‐mantle transition zone and caused exhumation related to Jurassic rifting The two-stage retrograde granulite metamorphism of lower-crustal and upper-mantle rocks path of the Malenco granulites separated by >50 My suggests that The magmatic crystallization of the gabbro was outlasted by ductile Permian extension and Jurassic rifting are two independent tectonic deformation, which is also observed in the other rocks of the processes The presence of hydrous, Cl-rich minerals at 600 ‐ crust‐mantle transition Two stages of retrograde metamorphism 50∞C and 0·8 ‐ 0·1 GPa requires input of externally derived followed Mineral parageneses in garnet‐kyanite gneiss, metagabbro, fluids at the base of 30 km thick continental crust into previously and metaperidotite record a first stage of near-isobaric cooling under dry granulites at the onset of Jurassic rifting These fluids were anhydrous conditions The stabilized crust‐mantle transition then generated by dehydration of continental crust juxtaposed during persisted over a period of about 50 My into the Late Triassic rifting with the hot, exhuming granulite complex along a active Exhumation of the crust‐mantle complex began with the onset of shear zone continental rifting during Early Jurassic This stage of retrograde metamorphism is recorded by near-isothermal decompression and partial hydration of the granulitic mineral assemblages The whole crust-to-mantle complex was then exposed in the Tethyan ocean KEY WORDS: subcontinental lithospheric mantle; granulite; continental near its Adriatic margin The magmatic assemblage of the Braccia rifting; retrograde metamorphism; Malenco

196 citations

Journal ArticleDOI
TL;DR: In this article, the authors present Sensitive High Resolution Ion Microprobe (SHRIMP) U and Pb isotope analyses of zircon from a charnockite and a charnsockite-hosted leucosome in order to determine the age of magmatism and anatexis related to high-grade metamorphism immediately to the north of the Palghat Cauvery Shear System (PCSS), a proposed Neoproterozoic terrane boundary within Southern India.

195 citations

Journal ArticleDOI
TL;DR: In this paper, the Fuping Complex and the adjoining Wutai and Hengshan Complexes are located in the central zone of the North China craton and the dominant rock types are high-grade tonalitic-trondhjemitic-granodioritic (TTG) gneisses, with minor amounts of mafic granulites, syntectonic granitic rocks and supracrustal rocks.
Abstract: The Fuping Complex and the adjoining Wutai and Hengshan Complexes are located in the central zone of the North China craton. The dominant rock types in the Fuping Complex are high-grade tonalitic–trondhjemitic–granodioritic (TTG) gneisses, with minor amounts of mafic granulites, syntectonic granitic rocks and supracrustal rocks. The petrological evidence from the mafic granulites indicates three stages of metamorphic evolution. The M1 stage is represented by garnet porphyroblasts and matrix plagioclase, quartz, orthopyroxene, clinopyroxene and hornblende. Orthopyroxene+plagioclase symplectites and clinopyroxene+plagioclase±orthopyroxene coronas formed in response to decompression during M2 following the peak metamorphism at M1. Hornblende+plagioclase symplectites formed as a result of further isobaric cooling and retrograde metamorphism during M3. The P–T estimates using TWQ thermobarometry are: 900–950 °C and 8.0–8.5 kbar for the peak assemblage (M1), based on the core compositions of garnet, matrix pyroxene and plagioclase; 700–800 °C and 6.0–7.0 kbar for the pyroxene+plagioclase symplectites or coronas (M2); and 550–650 °C and 5.3–6.3 kbar for the hornblende+plagioclase symplectites (M3), based on garnet rim and corresponding symplectic mineral compositions. These P–T estimates define a clockwise P–T path involving near-isothermal decompression for the Fuping Complex, similar to the P–T path estimated for the metapelitic gneisses. The inferred P–T path suggests that the Fuping Complex underwent initial crustal thickening, subsequent exhumation, and finally cooling and retrogression. This tectonothermal path is similar to P–T paths inferred for the Wutai and Hengshan Complexes and other tectonic units in the central zone of the North China craton, but different from anti-clockwise P–T paths estimated for the basement rocks in the eastern and western zones of the craton. Based on lithological, structural, metamorphic and geochronological data, the eastern and western zones of the craton are considered to represent two different Archean to Paleoproterozoic continental blocks that amalgamated along the central zone at the end of Paleoproterozoic. The P–T paths of the Fuping Complex and other tectonic units in the central zone record the collision between the eastern and western zones that led to the final assembly of the North China craton at c. 1800 Ma.

195 citations

Journal ArticleDOI
TL;DR: In this paper, two main clear-cut groups of granulites of the Variscan median Europe are distinguished based on differences in structural, petrological and radiometric features: Group I comprises lenses of eclogite-granulite scattered in the internal zones of the Hercynian belt; Group II includes granulitic slices related to deep-seated Alpine lineaments and xenoliths scavenged by recent volcanoes.

194 citations

Book ChapterDOI
01 Jan 1990
TL;DR: In this article, the authors evaluated the compositional differences between granulite terrains of various ages and xenoliths and the processes responsible for the formation of granulites.
Abstract: Geochemical data from the literature for high-pressure granulites have been compiled with the aim of evaluating the compositional differences between granulite terrains of various ages and xenoliths and the processes responsible for granulite formation. Although complete compositional overlap exists between the different granulite groups, median compositions of Archean granulite facies terrains are more evolved (having higher SiO2 and lower MgO) than post-Archean terrains, which are in turn more evolved than granulite xenoliths. The degree of LREE enrichment changes systematically as well, with Archean terrains having the highest (La/Sm)N and (La/Yb)N and xenoliths the lowest. In contrast to the secular changes observed in upper crustal composition, the median K2O content for Archean granulites is slightly higher than that of post-Archean terrains. K, Rb, Cs, Th and U distribution patterns of granulites are the same for terrains and xenoliths, suggesting similar depletion processes operate in both. It is possible to classify granulites on the basis of their LILE contents and thereby to predict their LILE characteristics if their K contents are known. K/U and K/Th ratios are significantly higher in granulites than in the upper continental crust and do not correlate with K content. Using the median values of K, K/Th and K/U for Archean granulite terrains, a heat production of 0.48 µW/m3 is calculated — a value similar to estimates based on individual terrains. Suggestions that mantle heat flow is overestimated in Archean shields due to the effects of lateral heterogeneities in heat-producing elements in the crust mean that Archean granulite terrains cannot be excluded as being representative of the lower crust in these regions on the basis of heat flow arguments. The heat production calculated for post-Archean terrains is somewhat higher (0.53 µW/m3) than the Archean value and that of xenoliths is very low (0.08 µW/m3). Model trace element contents of partial melting residues of metapelitic rocks, using recent experimental results to constrain restite phase proportions, are different from those observed in aluminous granulites. However, if melt segregation was inefficient, the trace element characteristics of the model restite are closer to those observed in aluminous granulites, but the residues are no longer LILE depleted. This suggests that (1) granite residues may be sampled as undepleted granulites, and (2) partial melting is not the process by which granulites become depleted in LILEs. Finally, positive Eu anomalies postulated to exist in the lower crust are observed mainly in cumulates, suggesting that crystal accumulation rather than partial melt removal may be the process responsible for imparting the negative Eu anomaly on the upper crust.

194 citations


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