Journal ArticleDOI
Granulites and related rocks in variscan median Europe: A dualistic interpretation
C. Pin,Daniel Vielzeuf +1 more
TLDR
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.Citations
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Experimental determination of the fluid-absent melting relations in the pelitic system
Daniel Vielzeuf,John R. Holloway +1 more
TL;DR: In this article, the melting of a natural metapelite under fluid-absent conditions was studied experimentally and a series of P-T, T-XH2O, and liquidus diagrams were proposed.
Journal ArticleDOI
Constraints on melting and magma production in the crust
John D. Clemens,Daniel Vielzeuf +1 more
TL;DR: In this article, the authors present a model for calculating the amounts of melt that may be formed by fluid-absent breakdown of micas and amphiboles in common crustal rock types (pelitic, quartzofeldspathic, intermediate and mafic).
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Multiple zircon growth and recrystallization during polyphase Late Carboniferous to Triassic metamorphism in granulites of the Ivrea Zone (Southern Alps): an ion microprobe (SHRIMP) study
TL;DR: In this paper, a metasedimentary and a meta-igneous quartz-feldspar granulite from the Val Sesia and Val Mastallone area of the Ivrea Zone (Southern Alps) are compared with respect to crystal morphology and U/Pb ages.
Journal ArticleDOI
Accretionary history and crustal evolution of the Variscan belt in Western Europe
TL;DR: The Variscan belt of Western Europe is part of a large intra-Paleozoic belt extending on both sides of the Atlantic from the Ouachitas in the US and the Mauritanides in West Africa to the Bohemian Massif in Czechoslovakia and Poland as discussed by the authors.
Journal ArticleDOI
High‐pressure granulites: formation, recovery of peak conditions and implications for tectonics
Abstract: High-pressure granulites are characterised by the key associations garnet-clinopyroxene-plagioclase-quartz (in basic rocks) and kyanite-K-feldspar (metapelites and felsic rocks) and are typically orthopyroxene-free in both basic and felsic bulk compositions. In regional metamorphic areas, two essential varieties exist: a high- to ultrahigh-temperature group and a group representing overprinted eclogites. The high- to ultrahigh-temperature type formerly contained high-temperature ternary feldspar (now mesoperthite) coexisting with kyanite, is associated with garnet peridotites, and formed at conditions above 900 °C and 1.5 GPa. Clinopyroxene in subordinate basic rocks is Al-rich and textural evidence points to a high-pressure–high-temperature melting history. The second variety contains symplectite-like or poikilitic clinopyroxene-plagioclase intergrowths indicating former plagioclase-free, i.e. eclogite facies assemblages. This type of rock formed at conditions straddling the high-pressure amphibolite/high-pressure granulite field at around 700–850 °C, 1.0–1.4 GPa. Importantly, in the majority of high-pressure granulites, orthopyroxene is secondary and is a product of reactions at pressures lower than the peak recorded pressure. In contrast to low- and medium-pressure granulites, which form at conditions attainable in the mid to lower levels of normal continental crust, high-pressure granulites (of nonxenolith origin) mostly represent rocks formed as a result of short-lived tectonic events that led to crustal thickening or subduction of the crust into the mantle. Short times at high-temperature conditions are reflected in the preservation of prograde zoning in garnet and pyroxene. High-pressure granulites of both regional types, although rare, are known from both old and young metamorphic terranes (e.g. c. 45 Ma, Namche Barwa, E Himalaya; 400–340 Ma, European Variscides; 1.8 Ga Hengshan, China; 1.9 Ga, Snowbird, Saskatchewan and 2.5 Ga Jianping, China). This spread of ages supports proposals suggesting that thermal and tectonic processes in the lithosphere have not changed significantly since at least the end of the Archean.
References
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An experimental investigation of the gabbro to eclogite transformation and its petrological applications
David H. Green,A.E. Ringwood +1 more
TL;DR: In this paper, a variety of basaltic compositions have been studied experimentally in the pressure range from 1 bar to 30 kb at temperatures above 1000°C and below the basalt solidus and the mineral assemblages are characterized by coexistence of garnet, clinopyroxene, plagioclase and, commonly, quartz.
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Eclogites and Eclogites: Their Differences and Similarities
TL;DR: In this article, a comparison of eclogites from different geologic occurrences but with similar bulk compositions demonstrates variation in Ca-Mg partition between coexisting garnet and pyroxene.
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Carbonic metamorphism, granulites and crustal growth
TL;DR: The hot-spot and plate-tectonic models of Precambrian crustal evolution lead to different schemes for CO2 delivery to continental roots as mentioned in this paper, and new tectonic concepts may be needed to explain carbonic metamorphism, minor-element depletions, and local phenomena of arrested development of charnockite in terrains.
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Experimental determination of kyanite-andalusite and andalusite-sillimanite equilibria; the aluminum silicate triple point
Journal ArticleDOI
Carbonation and melting reactions in the system CaO–MgO–SiO2–CO2 at mantle pressures with geophysical and petrological applications
Peter J. Wyllie,Wuu Liang Huang +1 more
TL;DR: In this paper, the authors review the positions of 14 decarbonation reactions, experimentally determined or estimated, extending the petrogenetic grid to mantle pressures to evaluate the effect of CO2 on model mantle peridotite composed of forsterite(Fo)+orthopyroxene(Opx)+clinopyroxenes(Cpx), each reaction terminates at an invariant point involving a liquid, CO2, carbonates, and silicates.