Abstract

Type 1 H 2 O-CO 2 , type 2 H 2 O-(CO 2 ), type 3 CH 4 -CO 2 -H 2 O, and type 4 CH 4 fluid inclusions. Type 1, type 3 and some type 2 inclusions are primary or pseudosecondary in origin, whereas type 4 and most type 2 inclusions are secondary. The primary (or pseudosecondary) type 1 and 2 inclusions homogenized at temperatures of 220 degrees to 385 degrees C. Secondary type 2 inclusions homogenized at 160 degrees to 215 degrees C. Crushing tests confirm the presence of CO 2 in samples with type 1 and 2 inclusions. Visually estimated X CO2 values in type 1 inclusions range from 3 to 24 mole percent with bulk molar volumes of 19 to 28 cm 3 /mole. Mineralizing fluids were at equilibrium with "graphite" at temperatures of 380 degrees to 480 degrees C and pressures of 1 to 3 kb. Calculated oxygen fugacities lie near the quartz-fayalite-magnetite buffer. The mineralizing fluids differ compositionally from fluids in other types of ore deposits but resemble fluids derived from metamorphic rocks and deep-level felsic intrusions.--Modified journal abstract.

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