Geologic, Fluid Inclusion, and Stable Isotope Studies of the Pasto Buena Tungsten-Base Metal Ore Deposit, Northern Peru

Huebnerite veins near Round Mountain, Nye County, Nevada

“…We use the assumptions that hydrostatic pressure prevailed and that the column of fluids extended upward to the surface. Like Landis and Rye (1974, p. We believe that clear quartz crystals that penetrate vugs, on which J. T. Nash (written commun., March 1980) determined filling temperatures of about 190°C and which contain no liquid carbon dioxide, were formed near the end of the initial episode of mineralization during which huebnerite was deposited. Temperatures at the beginning of this stage may have been much higher.…”

“…Nevertheless, Hollister (1970) pointed out that Bolivian tin districts and Peruvian and North American molybdenum porphyry districts are zoned outward from huebnerite-rich cores to ferberite-rich peripheral zones. Landis and Rye (1974) noted zonation outward from wolframite to ferberite in the Pasto Bueno tungstenbase metal district, Peru. Other studies in Tasmania, Europe, and the United States by Edwards and Lyon (1957), Baumann and Starke (1964), Bird and Gair (1976), Amosse (1978a), and Moore and Howie (1978), indicated more complex relations between H:F and environment.…”

“…He concluded that stout prismatic crystals grew at higher temperatures, whereas platy crystals grew at lower temperatures; iron-composition differences (0.5 weight percent between the two types) were slight, however. Landis and Rye (1974) showed at Pasto Bueno, Peru, that early-stage wolframite (75 weight percent MnW04) formed stubby bladed crystals and was deposited at a temperature of about 235°C and late-stage ferberite (<5 weight percent MnW04) formed elongate crystals and was deposited at a temperature of about 180°C. We note in the huebnerite veins near Round Mountain a tendency for stubby crystals to form where wall rock is schist, which also is at the lowest altitude of vein exposure and where huebnerite contains only about 0.2 weight percent FeO.…”

“…Wolframite-bearing vein systems that are spatially associated with granitic rocks commonly appear to have maximum development that is, show the greatest concentration of rich and large veins at and near the crests of cupolas. Examples are Panasqueira, Portugal (Kelly and Rye, 1979), Borralha, Portugal (Amosse, 1978b); several localities in Thailand (Shawe, personal observations, 1974); Pasto Bueno, Peru (Landis and Rye, 1974); Las Guijas, Arizona (Sheikh, 1970); several localities in Tasmania (Groves and Baker, 1972); and Cligga Head, Cornwall, England (Moore and Jackson, 1977). If the Round Mountain vein system had reached as high as cupolas near the apex of the granitic pluton, it would have had a vertical extent of 1.5-2 km.…”

Hydrothermal W-Mo mineralization of the Cheongyang mine, Republic of Korea: A fluid inclusion and stable isotope study.

“…Geology of the mine area has been described in detail by Kim (1977 (Shelton et al, 1986;So et al, 1983aSo et al, , b, 1991. Many famous worldwide W-bearing vein deposits (e. g., Pasto Bueno, Peru; Panasqueira, Portugal; San Cristobal, Peru) have similar complex mineralization sequences (Landis and Rye, 1974;Kelly and Rye, 1979;Campbell, 1983). This complex mineralization sequences in W bearing hydrothermal systems have been inter preted to be the results of later introduction of progressively larger volumes of cooler meteoric waters into early W-Mo-depositing magmatic hydrothermal systems (Shelton, 1984;So et al, 1991).…”