Results 241 to 250 of about 429,179 (286)

Hydrothermal Alteration in Some Granodiorites

Clays and clay minerals (National Conference on Clays and Clay Minerals), 1957
AbstractThe patterns of distribution of the mica and clay minerals resulting from alteration of feldspars are much less regular and well defined in the “porphyry copper” deposits than in the vein deposits such as those at Butte, Montana. There are, however, interpretative problems common to both.
Charles Meyer, Julian Hemley
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Weathering or hydrothermal alteration?

CATENA, 1983
Summary Altered granites are sometimes attributed to deep weathering, and sometimes to hydrothermal alteration. The nature of the evidence for the latter is discussed, and found inadequate in many instances. The alteration at Bega, Australia, and Dartmoor, England, is considered to result from deep weathering.
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Phillipsite alteration in hydrothermal brines

Materials Research Bulletin, 1987
Hydrothermal alteration of phillipsite in 3N chloride brines of Li+, Na+, K+, NH4+, Rb+, Cs+, Mg2+, Ca2+, Sr2+, Ba2+, Al2+, Fe3+, La3+, and Nd3+ was investigated at 300° C under a confining pressure of 30 MPa. Phillipsite altered to α spodumene in LiCl, to analcime and albite in NaCl, to orthoclase and leucite in KCl, NH4+-phillipsite in NH4Cl, to ...
Sridhar Komarneni, Rustum Roy
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Hydrothermal Alteration of the Oceanic Crust

1989
Recycling of the oceanic crust is potentially a dominant process in the formation of OIB mantle sources (Hofmann et al. 1978; 1986) and is a significant contribution to the flux of material between the continent and the depleted mantle (Albarede and Michard, 1986).
Francis Albarede, Annie Michard
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Hydrothermal Alteration and Weathering

1955
A considerable group of minerals, including the clay minerals, zeolites, pyrophyllite, chlorite, alunite, vermiculite, certain carbonates, sulfates, and other minerals under special circumstances, may originate through the interaction of thermal fluids and rock masses.
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Weathering and hydrothermal alteration: Critique of OLLIER's argument

CATENA, 1983
Summary We repeat our claim that weathering of granitic rocks of the Bega batholith was facilitated by hydrothermal action. We reject OLLIER's argument, and we report new mineralogical evidence in support of our case.
R.W. Young, J.C. Dixon
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Hydrothermal Alteration by Veins

1995
Sedimentary series, as well as crystalline basements, are cross-cut by fracture networks along which fluids of different origins (meteoric, connate, metamor-phic, magmatic) have percolated. Chemical interactions with rocks along these pathways produce secondary minerals among which phyllosilicates are usually the dominant species.
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Facies and types of hydrothermal alteration

Economic Geology, 1962
Most hydrothermally altered rocks are readily grouped into 2 principal facies, the argillic and phyllic (mica) facies. The argillic facies comprises the propylitic, montmorillonitic, and kaolinitic types, and the phyllic facies the muscovitic and biotitic types.
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Zeolites in Hydrothermally Altered Rocks

Reviews in Mineralogy and Geochemistry, 2001
Over the past 40 years, two universally accepted maxims of geology dealing with zeolite minerals have been shown to be incorrect: the first is that zeolites occur primarily as cavity fillings in basaltic igneous rocks, and the second is that these zeolites crystallized from so-called hydrothermal solutions, i.e. thermal waters from depth.
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Hydrothermal alteration of igneous rocks

Geological Society of America Bulletin, 1939
Many studies of individual examples of hydrothermal alteration have been made, but a general summary has not appeared since 1915. The changes due to hydrothermal alteration are textural, mineralogical, and chemical. As a rule the primary texture is destroyed, roughly in proportion to the intensity of alteration, but only in extreme examples is it ...
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