Progressive carbonation of high-Mg basalts during greenschist metamorphism, Victory Gold Mine, Kambalda, Western Australia
Mapping of inferred reaction isograds developed during regional greenschist metamorphism indicates progressive carbonation of the regional invariant assemblage of epidote-biotite-actinolite-albite-quartz-muscovite-ilmenite-sphene-magnetite. The initial stage of carbonation involves the replacement of actinolite and epidote by chlorite, calcite and biotite. Further carbonation converts aggregates of sphene, ilmenite and magnetite to rutile, carbonate and quartz. In extreme carbonation, chlorite and biotite are replaced by dolomite, muscovite and quartz. The degree of progressive carbonation increases with increasing intensity of foliation development; primary igneous textures are preserved in uncarbonated domains. Mineral reactions have been modeled in the system SiO/sub 2/-Al/sub 2/O/sub 3/-MgO-CaO-Na/sub 2/O-K/sub 2/-TiO/sub 2/-H/sub 2/O-CO/sub 2/ using mineral compositions determined by microprobe analyses. Equilibria at isograd surfaces indicate CO/sub 2/, H/sub 2/O and K/sub 2/O were added and/or removed by the metamorphic fluid. The ratio of CO/sub 2/ to H/sub 2/O in the metamorphic fluid was buffered by the mineral assemblage in low strain areas, whereas the assemblages of rocks developing the schist zones can be explained by an increase in the ratio of CO/sub 2/ to H/sub 2/O in the fluid toward the center of these zones. In a practical sense the mineral equilibrium may aid in mapping and interpreting areas of regional carbonation in metabasites and aid in the delineation of structures related to concentrations of gold.
- Research Organization:
- Western Mining Corporation, Kambalda (Australia)
- OSTI ID:
- 6611147
- Report Number(s):
- CONF-8510489-
- Journal Information:
- Geol. Soc. Am., Abstr. Programs; (United States), Vol. 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28 Oct 1985
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BASALT
GEOCHEMISTRY
METAMORPHISM
SCHISTS
MINERALOGY
PARAGENESIS
WESTERN AUSTRALIA
ALBITE
BIOTITE
CHEMICAL REACTION KINETICS
EPIDOTES
GEOLOGIC MODELS
GOLD ORES
MAGNETITE
MAPPING
MUSCOVITE
QUARTZ
ROCK-FLUID INTERACTIONS
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
AUSTRALASIA
AUSTRALIA
CALCIUM COMPOUNDS
CALCIUM SILICATES
CHALCOGENIDES
CHEMISTRY
FELDSPARS
IGNEOUS ROCKS
IRON COMPOUNDS
IRON ORES
IRON OXIDES
IRON SILICATES
KINETICS
METAMORPHIC ROCKS
MICA
MINERALS
ORES
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
REACTION KINETICS
ROCKS
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SILICON OXIDES
TRANSITION ELEMENT COMPOUNDS
VOLCANIC ROCKS
580400* - Geochemistry- (-1989)
580300 - Mineralogy
Petrology
& Rock Mechanics- (-1989)