Gold-quartz vein deposition in an uplifted blueschist terrane, Seward Peninsula, Alaska
The Big Hurrah mine, located on the Seward Peninsula, Alaska, consists of gold-quartz-carbonate veins which cut sheared carbonaceous metasedimentary and metavolcanic rocks. The rocks underwent regional syn-kinematic blueschist facies metamorphism in the Jurassic. Glaucophane in metabasite and mafic and pelitic schists has been reported from the central Seward Peninsula. Chlorite+/-epidote+/-albite+/-paragonite pseudomorphs after lawsonite and glaucophane have also been reported. The replacement of these blueschist facies minerals probably occurred during uplift and retrogradation of the terrane. The veins at Big Hurrah range from early, concordant metamorphic quartz lenses to discordant tension veins to discontinuous quartz-Au lodes which occur in sheared zones cross-cutting the foliation. The veins are thought to have formed during the late stages of shearing and uplift. Fluid inclusions in the veins are similar to those found in metamorphic rocks in that they are small, most are secondary, and may contain CO/sub 2/ and CH/sub 4/. The is evidence for CO/sub 2/-CH/sub 4//H/sub 2/O liquid immiscibility. Pressure estimates of 0.8 kbar were calculated from coexisting CO/sub 2/-CH/sub 4/ and aqueous inclusions. Pressure corrected homogenization temperatures for quartz deposition are in the range 300-400/sup 0/C. Hence, the veins were deposited at lower pressures and temperatures than those of the blueschist facies event. It is thought that the veins at Big Hurrah were formed during uplift by a fluid phase derived by metamorphic dehydration and channeled into conduits depositing quartz, carbonate and gold.
- Research Organization:
- Washington State Univ., Pullman (USA)
- OSTI ID:
- 6318644
- 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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ALASKA
GOLD ORES
MINERALIZATION
PETROLOGY
CARBONATE MINERALS
CHLORITE MINERALS
EPIDOTES
GEOBAROMETRY
GEOLOGIC HISTORY
GEOTHERMOMETRY
METAMORPHISM
MINERALOGY
PETROGENESIS
QUARTZ
SCHISTS
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
CALCIUM COMPOUNDS
CALCIUM SILICATES
CHALCOGENIDES
FEDERAL REGION X
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METAMORPHIC ROCKS
MINERALS
NORTH AMERICA
ORES
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
ROCKS
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SILICON OXIDES
TRANSITION ELEMENT COMPOUNDS
USA
580300* - Mineralogy
Petrology
& Rock Mechanics- (-1989)