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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 article, a microprobe analysis of 20 coexisting oligoclase (An18 3o) and microcline perthite (Ors7 87) pairs from charnockites and granitic gneisses gives KD(Na/(Na + Ca + K)plag/(Na/( Na + Ca+ K))or = 2-3 yielding temperatures of 650 ~ to 750~ in comparison to Seck's (1971) experimental and Stormer's (1975) calculated temperatures for inferred pres- sures of 8 kilobars.
Abstract: Thermometry of regionally metamorphosed granulites of the Adi- rondack Highlands has been undertaken using feldspar and iron-titanium- oxide equilibria. Electron microprobe analyses of 20 coexisting oligoclase (An18 3o) and microcline perthite (Ors7 87) pairs from charnockites and granitic gneisses give KD(Na/(Na + Ca + K)plag/(Na/(Na + Ca + K))or = 2-3 yielding temperatures of 650 ~ to 750~ in comparison to Seck's (1971) experimental and Stormer's (1975) calculated temperatures for inferred pres- sures of 8 kilobars. Microprobe analyses of 10 coexisting titaniferous magne- tite (ulv6spinels~ 1645) and ilmenite (hematitess 4.7-6.5) pairs from the Marcy massif anorthosite and related gabbros give temperatures of 620 ~ to 800 ~ C in comparison to Buddington and Lindsley's (1964) experimental data. Oxygen fugacities buffered by this assemblage range between 10-2~ and 10 16 and always lie within 10 +1 of thefo2 buffered by fayalite-magne- tite-quartz. Exsolved albite in alkali feldspar and ilmenite (oxidized ulv6spinel lamellae) must be reintegrated to infer metamorphic temperatures. Both thermometers give internally consistent, reproducible and geologically rea- sonable results. The inferred 750 ~ and 700~ isotherms wrap around the anorthosite massif in roughly concentric circles. Maximum metamorphic temperatures (790_+ 50 ~ C) occur between Saranac Lake and Tupper Lake, New York.

138 citations

Book ChapterDOI
01 Jan 1991
TL;DR: The Dahomeyide orogen is located along the southeastern margin of the West African craton, and is exposed throughout eastern Ghana, Togo, Benin, Nigeria and Cameroon as discussed by the authors.
Abstract: The Dahomeyide orogen is located along the southeastern margin of the West African craton, and is exposed throughout eastern Ghana, Togo, Benin, Nigeria and Cameroon (Fig. 1). The West African craton has remained tectnically stable since ca. 2000 Ma (Black 1985 a, b; Camil 1984). Western sectors of the craton are characterized by an Archean domain represented by grey gneisses and migmatitic complexes (amphibolite and granulite metamorphic facies), acid to basic granulites and charnockitic complexes, together with subordinate greenstone rocks, supracrustal metasedimentary and metavolcanoclastic rocks and granites. These rocks were affected by orogenic events at ca. 3000 Ma (Leonian) and ca. 2800 Ma (Liberian). Southeasternmost segments of the Archean domain were partially remobilized at ca. 1800 Ma during Eburnean orogenesis. Western sectors of this domain were variably affected by late Proterozoic (Pan-African) orogenic events.

138 citations

Journal ArticleDOI
TL;DR: In this paper, the responsiveness of zircon to granulite metamorphism and post-peak fluid infiltration in polymetamorphic terranes has been investigated using a case study from the Rauer Islands of East Antarctica.

138 citations

Journal ArticleDOI
TL;DR: In this paper, phase compositions in pelitic and mafic gneisses place tight constraints on pressure (ranging from 3 up to 6 kb), and temperature (500° up to 800° C) during prograde regional metamorphism of the Willyama Complex, Broken Hill, SE Australia.
Abstract: Phase compositions in pelitic and mafic gneisses place tight constraints on pressure (ranging from 3 up to 6 kb), and, to a lesser extent, on temperature (500° up to 800° C) during prograde regional metamorphism of the Willyama Complex, Broken Hill, SE Australia. These limits allow an evaluation of water activity across the terrain using various equilibria in pelitic and mafic gneisses. The stability of cummingtonite and biotite over much of the terrain places upper limits on temperature, and the presence of syn-metamorphic partial melts in the metasediments places lower limits on a(H2O). Garnet-biotitesillimanite-K feldspar-quartz relations combined with the partial melting data suggest a decrease in water activity from near 1.0 in the lower grade zones to 0.5±0.2 in the Broken Hill — Little Broken Hill part of the two pyroxene zone. This result is compatible with less precise hornblende-orthopyroxene-clinopyroxene-quartz relations.

138 citations

Journal ArticleDOI
TL;DR: A detailed U(-Th)-Pb geochronologic study of granulitized mafic eclogites and associated rocks from the footwall of the Ama Drime Massif yields important insights into the middle to late Miocene tectonic evolution of the Himalayan orogen as discussed by the authors.
Abstract: [1] The Ama Drime Massif (ADM) is an elongate north-south trending antiformal feature that extends ∼70 km north across the crest of the South Tibetan Himalaya and offsets the position of the South Tibetan Detachment system. A detailed U(-Th)-Pb geochronologic study of granulitized mafic eclogites and associated rocks from the footwall of the ADM yields important insights into the middle to late Miocene tectonic evolution of the Himalayan orogen. The mafic igneous precursor to the granulitized eclogites is 986.6 ± 1.8 Ma and was intruded into the paleoproterozoic (1799 ± 9 Ma) Ama Drime orthogneiss, the latter being similar in age to rocks previously assigned to the Lesser Himalayan Series in the Himalayan foreland. The original eclogite-facies mineral assemblage in the mafic rocks has been strongly overprinted by granulite facies metamorphism at 750°C and 0.7–0.8 GPa. In the host Ama Drime orthogneiss, the granulite event is correlated with synkinematic sillimanite-grade metamorphism and muscovite dehydration melting. Monazite and xenotime ages indicate that the granulite metamorphism and associated anatexis occurred at <13.2 ± 1.4 Ma. High-grade metamorphism was followed by postkinematic leucogranite dyke emplacement at 11.6 ± 0.4 Ma. This integrated data set indicates that high-temperature metamorphism, decompression, and exhumation of the ADM postdates mid-Miocene south directed midcrustal extrusion and is kinematically linked to orogen-parallel extension.

138 citations


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