Generation of an Archaean H/sub 2/O-CO/sub 2/ fluid enriched in Au, W and Mo by fractional crystallization in the Mink Lake intrusion, NW Ontario

Conference · Tue Jan 01 04:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6649728

Burrows, D R; Spooner, E T.C.

Fractional crystallization (FC) of the post-tectonic trondhjemitic Mink Lake intrusion in NW Ontario resulted in a residual H/sub 2/O-CO/sub 2/ low salinity fluid with an isotopic composition (delta /sup 13/C/sub cc/ x = -3.3 per thousand +/- 0.4 per thousand (1s), delta/sup 18/O/sub cc/ + 10.7 to 15.9 per thousand, deltaD/sub FI/ -70 +/- 9 per thousand (1s) and delta /sup 34/S/sub py/ +0.4 to +2.90 per thousand) compatible with magmatic derivation and extremely similar to that in vein quartz-carbonate-pyrite +/- scheelite, +/- tourmaline, +/- MoS/sub 2/ +/- telluride systems characteristic of major Archaean lode gold deposits. Inward FC of the granodiorite magma (69-71% SiO/sub 2/, Na/sub 2/O/K/sub 2/O = 1.6-3.9), as indicated by trace and REE data, produced a sequence of microgranites and aplitic dykes with mean values by INNA (n=10) for Au of 2.3ppb, Mo = 22ppm and W = 7.3ppm as compared to mean background values in the granodiorite of Au <1ppb, Mo less than or equal to 1ppm with W less than or equal to 3.7ppm (n=4). The latest aplites are observed to coexist with a H/sub 2/O-CO/sub 2/ mixture and are characterized by carbonate alteration selvages and minor MoS/sub 2/. Subsequent separation of the H/sub 2/O-CO/sub 2/ fluid and interaction with an otherwise fresh granodiorite within the already solidified southern margin, produced MoS/sub 2/ mineralized sub-horizontal quartz veins and larger tabular lenses of carbonate alteration without internal veining. Such zones are anomalously enriched (n=10) in Au (anti x = 153 pbb, range 2-570ppb) Mo (anti x 660ppm, range 1-2500ppm and W (anti x = 61 ppm, range 23-95 ppm).

• Research Organization: Univ. of Toronto, Ontario (Canada)
• OSTI ID: 6649728
• Report Number(s): CONF-8510489-
• Conference Information: Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Journal Volume: 17
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
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58 GEOSCIENCES
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580400* -- Geochemistry-- (-1989)
CANADA
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL ANALYSIS
CHEMICAL COMPOSITION
CRYSTALLIZATION
FLUIDS
FRACTIONATION
GEOTHERMAL FLUIDS
GOLD ORES
HYDROGEN COMPOUNDS
HYDROTHERMAL ALTERATION
IRON COMPOUNDS
IRON SULFIDES
ISOTOPE RATIO
MAGMATISM
MINERALIZATION
MINERALOGY
MINERALS
MOLYBDENUM ORES
NORTH AMERICA
ONTARIO
ORES
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PETROCHEMISTRY
PETROGENESIS
PHASE TRANSFORMATIONS
PYRITE
QUANTITATIVE CHEMICAL ANALYSIS
QUARTZ
SEPARATION PROCESSES
SILICON COMPOUNDS
SILICON OXIDES
SULFIDE MINERALS
SULFIDES
SULFUR COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TUNGSTEN ORES
WATER