Genetic aspects of a gold deposit in high grade Cambro-Ordovician metasediments, Nova Scotia: geological, mineral, geochemical and isotopic evidence
The Cochrane Hill gold deposit is hosted by amphibolite grade turbidite metasediments of the Cambro-Ordovician Goldenville Formation. Interbedded pelitic, semipelitic and psammite host sediments were polydeformed, metamorphosed and intruded by granitoid plutons during the Devonian Acadian Orogeny. Six distinct types of quartz veins are recognized from the 30m wide mineralized zone. Textural evidence suggests that vein emplacement commenced prior to deformation and ceased after the termination of the Acadian Orogeny. Essential mineralogy of the veins is quartz, plagioclase, phyllo-silicates, aluminosilicates, amphiboles and garnet. Arsenopyrite, pyrrhotite, loellingite, pyrite, marcasite, sphalerite, galena, chalcopyrite, Fe-Ti oxides and gold are the ore minerals. FeO/MgO, Na/sub 2/O/K/sub 2/O and Al/sub 2/O/sub 3//K/sub 2/O ratios in biotite and muscovite increase in the ore zone. Whole rock geochemistry of pelitic lithologies shows marked increases in TiO/sub 2//MgO, TiO/sub 2//Fe/sub 3/O/sub 3/, TiO/sub 2//P/sub 2/O/sub 5/ and Na O/K/sub 2/O ratios across the ore horizon. In the psammitic units TiO/sub 2//P/sub 2/O/sub 5/ shows marked increase whereas CaO/MgO and Na/sub 2/O/K/sub 2/O ratios decrease slightly in the auriferous zone. Fluid inclusion temperatures from quartz vary from 260 to +450/sup 0/C. Preliminary lead isotope data on galenas from Cochrane Hill are substantially more radiogenic than whole rock leads from the Goldenville Formation. These lead isotopic data, which are similar to those from granite-hosted mineral deposits together with other lines of evidence, support a granite related epigenetic gold models.
- Research Organization:
- Dept. of Mines and Energy, Halifax, Nova Scotia (Canada)
- OSTI ID:
- 6322545
- 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
15 GEOTHERMAL ENERGY
GOLD ORES
CHEMICAL COMPOSITION
GEOTHERMOMETRY
ISOTOPE RATIO
MINERALIZATION
MINERALOGY
AMPHIBOLE
BIOTITE
CAMBRIAN PERIOD
CHALCOPYRITE
FELDSPARS
GALENA
GARNETS
GEOCHEMISTRY
GEOLOGIC FORMATIONS
GEOLOGIC MODELS
MUSCOVITE
NOVA SCOTIA
ORDOVICIAN PERIOD
OROGENESIS
PYRITE
QUARTZ
SPHALERITE
CANADA
CHALCOGENIDES
CHEMISTRY
COPPER COMPOUNDS
COPPER SULFIDES
GEOLOGIC AGES
IRON COMPOUNDS
IRON SULFIDES
LEAD COMPOUNDS
LEAD SULFIDES
MICA
MINERALS
NORTH AMERICA
ORES
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PALEOZOIC ERA
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SILICON OXIDES
SULFIDE MINERALS
SULFIDES
SULFUR COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
580300* - Mineralogy
Petrology
& Rock Mechanics- (-1989)
152004 - Geothermal Data & Theory- Isotope & Trace Element Studies
580400 - Geochemistry- (-1989)