Abstract
An integrated geochemical analysis of the well-exposed Pine Creek, California tungsten skarn deposit has been undertaken to evaluate changes in chemical gradients across various lithologies. Thermodynamic calculations using available experimental and thermodynamic data allow limits to be assigned to the activities of important chemical components in the metasomatic environment. Quantifiable changes in “non-volatile” component activites (CaO, MgO, Al2O3, Fe2O3, WO3) and in fugacities (O2, F2) have been traced across the system. The activities of Al2O3, Fe2O3 and WO3 generally increase from the marble (<102, <10−6, <10−5 respectively), through the outer skarn zone and into the massive garnet skarn (10−1.7±0.3, 10−3.4±0.4, 10−4.8±0.1) While CaO and MgO activities decrease for the same traverse from 10−5 and 10−2.1±1 respectively, to <10−5.7 and <10−3. Calculated oxygen fugacities are 10−23.5+1.0 at T=800 K (527° C), about one log unit below QFM, and more reducing than that required by Mt-Py-Po. The high variance of the garnet-pyroxene-quartz assemblages adds sufficient uncertainty to the calculated activities for individual specimens that only the large-scale trends survive the small-scale scatter. None of the chemical variables emerge as major independent or controlling factors for the mineralogy or phase compositions. Changes in the activity of one component may be offset by compensatory changes in another resulting in an environment that, while different from Pine Creek, could still host scheelite mineralization. Mass balance calculations indicate that the exposed endoskarn cannot have supplied the necessary chemical components to convert the country rock to skarn.
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References
Bateman PC (1965) Geology and tungsten mineralization of the Bishop District, California. US Geol Surv Prof Paper 470:208
Bird DK, Helgeson HC (1980) Chemical interaction of aqueous solutions with epidote-feldspar mineral assemblages in geologic systems. 1. Thermodynamic analysis of phase relations in the system CaO-FeO-Fe2O3-Al2O3-SiO2-H2O-CO2. Am J Sci 280:907–941
Bohlen SR, Essene EJ (1978) The significance of metamorphic fluorite in the Adirondacks. Geochim Cosmochim Acta 42:1669–1678
Bowman JR (1978) Contact metamorphism, skarn formation, and origin of C-O-H skarn fluids in the Black Butte aureole, Elkhorn, Montana. Unpub PhD thesis, Univ Michigan
Bowman JR, Essene EJ (1984) Contact skarn formation at Elkhorn Montana I; P-T-component activity conditions of early skarn formation. Am J Sci 284:597–650
Brown PE (1980) A petrologic and stable isotopic study of skarn formation and mineralization at the Pine Creek, California tungsten mine. Unpub PhD thesis, Univ Michigan
Brown PE, Bowman JR, Kelly WC (1985) Petrologic and stable isotopic constraints on the source and evolution of skarn-forming fluids at Pine Creek, California. Econ Geol 80:72–95
Burt DM (1971a) Some phase equlibria in the system Ca-Fe-Si-C-O. Carnegie Inst Wash Year Book 70:178–184
Burt DM (1971b) The facies of some Ca-Fe-Si skarns in Japan. Carnegie Inst Wash Year Book 70:185–188
Burt DM (1972a) The influence of fluorine on the facies of Ca-Fe-Si skarns. Carnegie Inst Wash Year Book 71:443–450
Burt DM (1972b) Silicate-sulfide equilibria in Ca-Fe-Si skarn deposits. Carnegie Inst Wash Year Book 71:450–457
Burt DM (1978) Multisystems analysis of beryllium mineral stabilities: The system BeO-Al2O3-SiO2-H2O. Am Mineral 63:664–676
Burton JC, Taylor LA, Chou IM (1982) The f(O2)-T and f(S2)-T stability relations of hedenbergite and of hedenbergite-johannsenite solid solutions. Econ Geol 77:764–783
Carmichael ISE, Turner FJ, Verhoogen J (1974) Igneous Petrology. McGraw-Hill Book Co, New York, pp 50–59
Charlu TV, Newton RC, Kleppa OJ (1978) Enthalpy of some lime silicates by high temperature solution calorimetry with discussion of high pressure phase equilibria. Geochim Cosmochim Acta 42:367–375
Cressey G, Schmid R, Wood BJ (1978) Thermodynamic properties of almandine-grossular garnet solid solutions. Contrib Mineral Petrol 55:397–404
Einaudi MT (1977) Petrogenesis of copper-bearing skarn at the Mason Valley mine, Yerington district, Nevada. Econ Geol 72:769–795
Einaudi MT, Meinert LD, Newberry RJ (1981) Skarn deposits. Econ Geology, 75th Anniv Vol:317–391
Froese E, Gordon TM (1974) Activity coefficients of coexisting pyroxenes. Am Mineral 59:204–205
Gamble RP (1982) An experimental study of sulfidation reactions involving andradite and hedenbergite. Econ Geol 77:784–797
Ganguly J (1976) The energetics of natural garnet solid solution II. Mixing of the calcium silicate end-members. Contrib Mineral Petrol 55:81–90
Ganguly J, Kennedy GC (1974) The energetics of natural garnet solid solutions. I. Mixing of the aluminosilicate end-members. Contrib Mineral Petrol 48:137–148
Gustafson W (1974) The stability of andradite, hedenbergite and related minerals in the system Ca-Fe-Si-O-H. J Petrol 15:455–496
Helgeson HC, Delany JM, Nesbitt HW, Bird DK (1978) Summary and critique of the thermodynamic properties of rock-forming minerals. Am J Sci 178-A:1–229
Hensen BJ, Schmid R, Wood BJ (1975) Activity-composition relationships for pyrope-grossular garnet. Contrib Mineral Petrol 51:151–166
Huckenholz HG, Lindhuber W, Fehr KT (1981) Stability relationships of grossular+quartz+wollastonite+anorthite I. The effect of andradite and albite. Neues Jahrb Mineral Abh 142:223–247
Krumhansl JL (1977) Geochemistry of tungsten. Unpub PhD thesis, Stanford Univ
Kwak TAP (1978) The conditions of formation of the King Island scheelite contact skarn, King Island, Tasmania, Australia. Am J Sci 278:969–999
Liou JG (1974) Stabilitiy relations of andradite-quartz in the system Ca-Fe-Si-O-H. Am Mineral 59:1016–1025
Lyon WG, Westrum EF (1968) Low-temperature thermal properties of calcium tungstate. J Chem Physics 49:3374–3377
Morgan BA (1975) Mineralogy and origin of skarns in the Mount Morrison Pendant, Sierra Nevada, California. Am J Sci 275:119–142
Navrotsky A, Coons WE (1976) Thermochemistry of some pyroxenes and related compounds. Geochim Cosmochim Acta 40:1281–1288
Newberry RJ (1980) The geology and chemistry of skarn formation and tungsten deposition in the central Sierra Nevada, California. Unpub PhD thesis, Stanford Univ
Newberry RJ (1982) Tungsten-bearing skarns of the Sierra Nevada. I. The Pine Creek mine, California. Econ Geol 77:823–844
Newberry RJ (1983) The formation of subcalcic garnet in scheelite-bearing skarns. Canad Mineral 21:529–544
Newton RC, Charlu T, Kleppa OJ (1977) Thermochemistry of high pressure garnets and clinopyroxenes of the system CaO-MgO-Al2O3-SiO2. Geochim Cosmochim Acta 41:369–377
Robie RA, Hemingway BS, Fisher JR (1978) Thermodynamic properties of minerals and related substances at 298.15 K and 1 bar (105 pascals) pressure and at higher temperatures. US Geol Surv Bull 1452:456
Robinson GR, Haas JL, Schafer CM, Haselton HT (1983) Thermodynamic and thermophysical properties of selected phases in the MgO-SiO2-H2O-CO2, CaO-Al2O3-SiO2-H2O-CO2, and Fe-FeO-Fe2O3-SiO2 chemical systems, with special emphasis on the properties of basalts and their mineral components. US Geol Surv Open File Rep 83–0079:465
Saxena SK (1973) Thermodynamics of Rock-Forming Crystalline Solutions. Springer, Berlin New York
Saxena SK (1976) Two-pyroxene geothermometer: a model with an approximate solution. Am Mineral 61:643–652
Taylor BE (1976) Origins and significance of C-O-H fluids in the formation of Ca-Fe-Si skarn, Osgood Mountains, Humboldt County, Nevada. Unpub PhD thesis, Stanford Univ
Taylor BE, Liou JG (1978) The low temperature stability of andradite in C-O-H fluids. Am Mineral 63:378–393
Wright WA (1973) Skarn-formation at Pine Creek mine, Bishop, California. Unpub PhD thesis, Univ California, Berkeley
Yakovleva RA, Rezukhina TN (1960) The heat capacity of calcium, manganese and cobalt tungstates at high temperatures. Russ J Physical Chem 34:390–392
Zharikov VA (1970) Skarns. Internat Geol Rev 12:541–559, 619–647, 760–775
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Brown, P.E., Essene, E.J. Activity variations attending tungsten skarn formation, Pine Creek, California. Contrib Mineral and Petrol 89, 358–369 (1985). https://doi.org/10.1007/BF00381557
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DOI: https://doi.org/10.1007/BF00381557