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Crustal rhyolite melts at mantle depths
2023Melts with rhyolite compositions originate from partial melting of crustal rocks or extensive differentiation of basaltic melts, at temperatures in the range of 800 °C. Accordingly, they are confined to the shallow continental crust. Nevertheless, experimental studies have demonstrated that dacite-rhyolite melts can be generated at higher ...
Dallai L. +7 more
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Lithos, 2014
Abstract Ascent of granitic melt initiates under suprasolidus conditions in the mid- to lower crust before continuing through subsolidus rocks to higher crustal levels. Whereas migration of melt in suprasolidus rocks can occur in pervasive net-like structures and involve relatively small melt volumes, ascent through the subsolidus crust requires more
Johann F.A. Diener +2 more
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Abstract Ascent of granitic melt initiates under suprasolidus conditions in the mid- to lower crust before continuing through subsolidus rocks to higher crustal levels. Whereas migration of melt in suprasolidus rocks can occur in pervasive net-like structures and involve relatively small melt volumes, ascent through the subsolidus crust requires more
Johann F.A. Diener +2 more
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Mechanisms of melt extraction during lower crustal partial melting
Journal of Metamorphic Geology, 2020AbstractProgressive vapour‐absent partial melting of a closed rock system increases melt pressure due to an expansion in the volume of the mineral plus melt assemblage. For a locally closed system, we quantify the melt pressure increase per increment of partial melting of a metapelite using phase equilibria modelling and combine it with Mohr–Coulomb ...
Michael A. Etheridge +3 more
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Geology, 2003
We propose that the internally zoned, Li-bearing Tin Mountain pegmatite in the Harney Peak granite-pegmatite system of the Black Hills, South Dakota, crystallized from fluid-rich, compositionally complex melts at ∼400–350 °C. The low crystallization temperatures resulted from the combined fluxing effects of Li, B, P, H 2 O, and carbonate anions.
Mona-Liza C. Sirbescu, Peter I. Nabelek
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We propose that the internally zoned, Li-bearing Tin Mountain pegmatite in the Harney Peak granite-pegmatite system of the Black Hills, South Dakota, crystallized from fluid-rich, compositionally complex melts at ∼400–350 °C. The low crystallization temperatures resulted from the combined fluxing effects of Li, B, P, H 2 O, and carbonate anions.
Mona-Liza C. Sirbescu, Peter I. Nabelek
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Partial melting of crustal rocks
Engineering Geology, 1989Abstract Shales and graywackes were first metamorphosed at 650°C and then partially melted at 700 and 750°C at 2, 4, 6, and 8 kilobars in the presence of 0.75m NaCl−0.45m KCl and 0.225m CaCl2−0.750m NaCl solutions. In experiments with shales,KK+Na ratio in the decreases with increasing pressure at 650 and 700°C; however, at 750°C this ratio is equal ...
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Crustal melting by ponding of mafic magmas: A numerical model
Journal of Volcanology and Geothermal Research, 1998Abstract We examine the possibility that an abating period of mantle-related volcanic activity at continental margins triggers the production of crustal-derived melts. A vertical zone, permeated by rising mafic melts, is established below the volcanic arc if long-lasting mantle-derived magmatism occurs.
Laube, N., Springer, J.
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Melt Segregation Mechanism Controls on the Geochemistry of Crustal Melts
Mineralogical Magazine, 1994Crustally-derived granites may be generated in a variety of tectonic settings, but whatever the ultimate causse of heating crustal thickening, crustal extension, enhanced heat flux from the mantle, or magmatic advection by mantle-derived melts crustal melting likely occurs in a dynamic environment.
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Crustal melting in nature: Prosecuting source processes
Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy, 1999Abstract Observational data and geochronology show synchronous deformation, metamorphism and intrusion of granite in many obliquely convergent (transpressive) orogenic belts. In these belts, melt extraction and transport was by syntectonic pulsed flow in structurally-controlled channels through migmatites, and granite plutons were constructed by ...
M Brown, R.A Pressley
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Influence of volatiles in the generation of crustal anatectic melts
Journal of Geochemical Exploration, 2000Abstract The study of volatile elements in crustal anatectic terranes may provide information about the role of fluid flow and fluid pathways during high-temperature metamorphism. We have studied the distribution of B in migmatites and leucogranites associated with the Ronda peridotites, Betic Cordilleras (SE Spain). The migmatites underlie the Ronda
A Acosta, M.D Pereira, D.M Shaw
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Crustal melting and melt extraction, ascent and emplacement in orogens: mechanisms and consequences
Journal of the Geological Society, 2007Significant volume of wet melting requires an influx of H 2 O-rich volatile phase. In hydrate-breakdown melting, initial melt accumulation is diffusion-controlled and melt accumulates around peritectic phases in low-pressure sites.
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