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Titolo:
Dissolution of primary minerals in natural waters - II. Mineral saturationstate
Autore:
Stefansson, A; Gislason, SR; Arnorsson, S;
Indirizzi:
Univ Iceland, Inst Sci, IS-107 Reykjavik, Iceland Univ Iceland ReykjavikIceland IS-107 nst Sci, IS-107 Reykjavik, Iceland
Titolo Testata:
CHEMICAL GEOLOGY
fascicolo: 3-4, volume: 172, anno: 2001,
pagine: 251 - 276
SICI:
0009-2541(20010215)172:3-4<251:DOPMIN>2.0.ZU;2-4
Fonte:
ISI
Lingua:
ENG
Soggetto:
THERMODYNAMIC PROPERTIES; HIGH-PRESSURES; BASALT INTERACTIONS; GEOTHERMAL WATERS; ICELAND; TEMPERATURES; SOLUBILITY; EQUILIBRIA; CHEMISTRY; SPECIATION;
Keywords:
basalt; mineral stability; cold water; geothermal water; weathering;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
61
Recensione:
Indirizzi per estratti:
Indirizzo: Stefansson, A ETH Zentrum, Inst Mineral & Petrog, Sonneggstr 5, CH-8092 Zurich, Switzerland ETH Zentrum Sonneggstr 5 Zurich Switzerland CH-8092 zerland
Citazione:
A. Stefansson et al., "Dissolution of primary minerals in natural waters - II. Mineral saturationstate", CHEM GEOL, 172(3-4), 2001, pp. 251-276

Abstract

The saturation state of olivine, plagioclase, clinopyroxene, orthopyroxene, Fe-Ti oxides and apatite of variable composition has been assessed in natural waters in Iceland, with temperature ranging from 0 degreesC to 300 degreesC and in situ pH from below 5 to above 10. Cold waters are undersaturated with respect to olivine, orthopyroxene, clinopyroxene and plagioclases indicating that all these minerals tend to dissolve under weathering conditions. With increasing pH and temperature, the waters approach saturation with pyroxene, olivine, and plagioclases. Also, the degree of undersaturation of olivine and orthopyroxene decreases with increasing Fe content of the minerals and Fe-rich olivine and orthopyroxene are stable between 50 degreesCand 150 degreesC, whereas Mg-rich ones tend to dissolve. Natural waters inIceland are saturated with respect to pure albite when above 50 degreesC. They are, on the other hand, undersaturated with Ca-rich plagioclase up to 250 degreesC where the waters reach saturation. Pure magnetite and hematiteare stable at all temperatures. With increasing titanium content, the minerals become unstable, and the waters are undersaturated with respect to pure ulvospinel at temperatures up to 300 degreesC. Pure ilmenite is, however,close to saturation under weathering conditions but undersaturated above 200 degreesC. F-apatite is close to saturation at all temperatures. On the other hand, undersaturation with respect to OH-apatite is observed at all temperatures. The weathering susceptibilities of primary minerals of basalt in Icelandic waters in increasing order are Mg-olivine > Fe-olivine, Ti-richmagnetite > Ca-plagioclase, Mg-orthopyroxene > Fe-orthopyroxene, clinopyroxene > Na-plagioclase, F-apatite > Ti-rich ilmenite >> Ti-poor magnetite, Ti-poor hematite. (C) 2001 Elsevier Science B.V. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 03/12/20 alle ore 16:01:40