Results 191 to 200 of about 2,459 (233)

Melt Segregation Mechanism Controls on the Geochemistry of Crustal Melts

Mineralogical Magazine, 1994
Crustally-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, 1999
Abstract 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, 2000
Abstract 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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Melting the myth: Prograde garnet dissolves during early crustal melting

Geology
Abstract Garnet is widely thought to increase in stability and volume during prograde metamorphism and partial melting. Yet, whether early-formed subsolidus garnet persists or breaks down when melting begins remains an open question.
Lucas R. Tesser, Pierre Lanari, Jacob B. Forshaw, Thorsten A. Markmann, Mathias Hueck, Benita Putlitz, Noralinde de Leijer, Cauê R. Cioffi, Miguel A.S. Basei, Carlos E. Ganade   +9 more
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Behaviour of zircon and monazite during crustal melting

Journal of the Geological Society, 2014
Ages retrieved from accessory minerals in high-grade metamorphic rocks place important constraints on the timing of events and the rates of tectonometamorphic processes operating in the deep crust. In suprasolidus rocks, the dissolution and growth of zircon and monazite are strongly dependent on the P–T conditions ...
Chris Yakymchuk, Michael Brown
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Crustal melting and melt extraction, ascent and emplacement in orogens: mechanisms and consequences

Journal of the Geological Society, 2007
Significant 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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Rheological transitions and the progress of melting of crustal rocks

Earth and Planetary Science Letters, 1998
Abstract High-grade igneous and metamorphic systems which possess a variable percentage of melt, may undergo a transition between crystal-supported and fully fluid behavior. The melt-fraction interval over which this transition occurs is not well constrained. We have conducted six series of numerical simulations of crustal melting using melt-fraction
Scott A Barboza, George W Bergantz
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Crustal melting and granite magmatism: key issues

Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy, 2001
Abstract The thermal and rheological structure of orogens determines their mechanical behaviour. Collosional orogens are characterized by a clockwise P-T evolution, which means that in the core, where temperatures exceed the wet solidus for common crustal rocks, melt may be present during orogenesis.
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Controls on the trace element composition of crustal melts

Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 1996
ABSTRACT:The behaviour of trace elements during partial melting depends primarily on their mode of occurrence. For elements occurring as trace constituents of major phases (e.g. Li, Rb, Cs, Eu, Sr, Ba, Ga, etc.), slow intracrystalline diffusion (D ≍ 10−16 cm2 s−1) at the temperature range of crustal anatexis causes all effective crystal-melt partition ...
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Electrical conductivity of water‐undersaturated crustal melting

Journal of Geophysical Research: Solid Earth, 1986
Water‐undersaturated melting in the crust can occur at lithostatic pressure in the presence of an H2O‐CO2 fluid, of no CO2 or fluid but with all H2O bound structurally in hydrous minerals, or of an insufficient amount of H2O fluid to saturate a melt at liquidus temperatures. The composition of any fluid in equilibrium with possible source rocks depends
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