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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: Xenoliths of subducted crustal origin hosted by Miocene ultrapotassic igneous rocks in the southern Pamir provide important new information regarding the geological processes accompanying tectonism during the Indo-Eurasian collision as mentioned in this paper.
Abstract: Xenoliths of subducted crustal origin hosted by Miocene ultrapotassic igneous rocks in the southern Pamir provide important new information regarding the geological processes accompanying tectonism during the Indo-Eurasian collision Four types have been studied: sanidine eclogites (omphacite, garnet, sanidine, quartz, biotite, kyanite), felsic granulites (garnet, quartz, sanidine and kyanite), basaltic eclogites (omphacite and garnet), and a glimmerite (biotite, clinopyroxene and sanidine) Apatite, rutile and carbonate are the most abundant minor phases Hydrous phases (biotite and phengite in felsic granulites and basaltic eclogites, amphiboles in mafic and sanidine eclogites) and plagioclase form minor inclusions in garnet or kyanite Solid-phase thermobarometry reveals recrystallization at mainly ultrahigh temperatures of 1000–1100 C and nearultrahigh pressures of 2 5–2 8GPa Textures, parageneses and mineral compositions suggest derivation of the xenoliths from subducted basaltic, tonalitic and pelitic crust that experienced highpressure dehydration melting, K-rich metasomatism, and solid-state re-equilibration The timing of these processes is constrained by zircon ages from the xenoliths and Ar/Ar ages of the host volcanic rocks to 57–11Ma These xenoliths reveal that deeply subducted crust may undergo extensive dehydration-driven partial melting, density-driven differentiation and disaggregation, and sequestration within the mantle These processes may also contribute to the alkaline volcanism observed in continent-collision zones

182 citations

Journal ArticleDOI
01 Jan 1968-Lithos
TL;DR: In this article, it is considered that the medium to high pressure granulite terranes reflect chemical trends with increasing depth in the continental crust, these trends are the results of modifications of the original compositions by metamorphic (including melting) processes.

182 citations

Journal ArticleDOI
TL;DR: In this article, the authors summarize recent advances in knowledge of the Texas basement and propose plate models to explain the tectonic evolution of this margin during Mesoproterozoic time.
Abstract: The Grenville orogenic belt along the southern margin of Laurentia records more than 300 m.y. of orogenic activity culminating in arc-continent and continent-continent collision ca. 1150–1120 Ma. Exposures in Texas provide a unique profile across the Grenville orogen from the orogen core to the cratonal margin. In the Llano uplift of central Texas, ca. 1360–1232 Ma upper amphibolite–lower granulite facies, polydeformed supracrustal and plutonic rocks represent the core of the collisional orogen. This exposure contains a suture between a 1326–1275 Ma exotic island-arc terrane and probable Laurentian crust and records A-type subduction. In west Texas, 1380–1327 Ma amphibolite to greenschist facies, polydeformed supracrustal rocks are thrust over ca. 1250 Ma carbonate and volcanic rocks along the cratonal margin. The carbonate and volcanic rocks form a narrow thrust belt with post–1123 Ma synorogenic sedimentary rocks, which grade into undeformed sedimentary rocks northward on the Laurentian craton. The Texas basement reveals a consistent but evolving tectonic setting for the southern margin of Laurentia during Mesoproterozoic time. This paper summarizes recent advances in our knowledge of the Texas basement and proposes plate models to explain the tectonic evolution of this margin during Mesoproterozoic time. The orogenic history is strikingly similar to that of the Canadian Grenville orogen and requires a colliding continent off the southern Laurentian margin during the assembly of Rodinia.

182 citations

Journal ArticleDOI
TL;DR: The preservation of premetamorphic, whole-rock oxygen isotope ratios in Adirondack metasediments shows that neither these rocks nor adjacent anorthosites and gneisses have been penetrated by large amounts of externally derived, hot CO2-H2O fluids during granulite facies metamorphism as mentioned in this paper.
Abstract: The preservation of premetamorphic, whole-rock oxygen isotope ratios in Adirondack metasediments shows that neither these rocks nor adjacent anorthosites and gneisses have been penetrated by large amounts of externally derived, hot CO2-H2O fluids during granulite facies metamorphism. This conclusion is supported by calculations of the effect of fluid volatilization and exchange and is also independently supported by petrologic and phase equilibria considerations. The data suggest that these rocks were not an open system during metamorphism; that fluid/rock ratios were in many instances between 0.0 and 0.1; that externally derived fluids, as well as fluids derived by metamorphic volatilization, rose along localized channels and were not pervasive; and thus that no single generalization can be applied to metamorphic fluid conditions in the Adirondacks.

182 citations

Journal ArticleDOI
TL;DR: In this paper, the authors used receiver function analysis at 32 sites on the Archaean and Proterozoic terrains of South India to determine the crustal thickness and Poisson's ratio of the Western Dharwar Craton.
Abstract: [1] We present crustal thickness and Poisson's ratio determinations from receiver function analyzes at 32 sites on the Archaean and Proterozoic terrains of South India. The crustal thickness in the late Archaean (2.5 Ga) Eastern Dharwar Craton varies from 34–39 km. Similar crustal thickness is observed beneath the Deccan Volcanic Province and the Cuddapah basin. The most unexpected result is the anomalous present-day crustal thickness of 42–51 km beneath the mid-Archaean (3.4–3.0 Ga) segment of the Western Dharwar Craton. Since the amphibolite-grade metamorphic mineral assemblages (5–7 Kbar paleopressures) in this part of Western Dharwar Craton equilibrated at the depths of 15–20 km, our observations suggest the existence of an exceptionally thick (57–70 km) crust 3.0 Ga ago. Beneath the exhumed granulite terrain in southernmost India, the crustal thickness varies between 42–60 km. The Poisson's ratio ranges between 0.24–0.28 beneath the Precambrian terrains, indicating the presence of intermediate rock type in the lower crust. These observations of thickened crust suggest significant crustal shortening in South India during the Archaean.

181 citations


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