Results 181 to 190 of about 3,014 (216)

Metasomatism and Intrusion in Jamaica

Geological Magazine, 1942
The nearest known pre-Cretaceous rocks to Jamaica are Jurassic in Western Cuba, and Carboniferous in Colombia, Venezuela, and Honduras, all about 500 miles away. The evolution of Jamaica seems to have been somewhat as follows. Andine (?) orogenesis on or near the site took place, accompanied by magmatic invasion; the rocks are nowhere seen “in situ ...
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Carbonatite metasomatism in the mantle : sources and roles of carbonate in metasomatic enrichment processes in the lithosphere

2023
Recent high pressure experimental work in the Hawaiian pyrolite+H20+C02 system (Wallace and Green, 1988; Falloon and Green, 1990) has revealed the presence of a stability field for high Mg/(Mg+LFe), sodic dolomitic carbonatite melt in equilibrium with pargasitic lherzolite at pressures greater than the decarbonation reaction opx + dol = ol + cpx + C02.
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Metasomatic and non-metasomatic low grade metamorphism of Ordovician meta-bentonites in Sweden

Geochimica et Cosmochimica Acta, 1982
Abstract Bulk rock and electron microprobe analyses of two series of meta-bentonite beds one of which was subjected to low grade metamorphic conditions indicate that: 1. (a) K is the most important element in the metasomatic transformation of volcanic ash into bentonite clay mineral assemblages.
A.M. Brusewitz, Bruce Velde
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Equations of metasomatic reactions

International Geology Review, 1980
(1980). Equations of metasomatic reactions. International Geology Review: Vol. 22, No. 11, pp. 1257-1258.
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The theory of metasomatic zoning

Mineralium Deposita, 1968
The main features of the theory of metasomatic zoning, developed by the author, are here exposed. The basic differential equations of metasomatic zoning, of the infiltration as well as of the diffusion type, are deduced for the conditions of local equilibrium, the kinetic phenomena being neglected.
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Thermodynamic Modeling and Thermobarometry of Metasomatized Rocks

2012
Determining the P-T conditions at which metasomatism occurs provides insight into the physical conditions at which fluid-rock interaction occurs in the crust. However, application of thermodynamic modeling to metasomatized rocks is not without pitfalls.
Didier Marquer, Philippe Goncalves, Emilien Oliot, Emilien Oliot, Cyril Durand   +4 more
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Potassium metasomatism of Precambrian paleosols

Precambrian Research, 2015
Abstract Independent of substratum composition, ancient regoliths formed by subaerial weathering are characterized by accumulation of K and other alkaline elements. Potassium enrichment due to the formation of clay-minerals is a trend typically observed in regoliths developed by modern hypergene processes.
Alexey A. Novoselov, Carlos Roberto de Souza Filho   +1 more
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The types and mechanisms of metasomatism

International Geology Review, 1967
Metasomatism is considered as a group of various replacement phenomena - the effect of pore fluids and surface energy at the solid-fluid interface. Various types of metasomatism are identified, dependent on the volume of equilibrium mineral-forming systems and types of equilibrium, distance of mass-exchange, stage nature of the metasomatic process ...
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Metasomatic Alteration of Ultramafic Rocks

1989
Metasomatized ultramafic rocks from the 3800 Ma Isua supracrustal belt have been preferentially enriched in calcium, aluminium and silica, but show no or only little addition of potassium and rubidium. This unusual geochemical response to fluid infiltration can be explained in the light of a low buffered activity of aqueous silica during progressive ...
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Mantle metasomatism—perspective and prospect

Geological Society, London, Special Publications, 1987
Summary Mantle replenishment in lithophile elements has been discerned in the patterns of trace elements and isotopes in lavas. One replenishment process is identified as metasomatic replacement, seen in ultramafic xenoliths brought up in high-velocity alkaline eruptions.
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