Hostname: page-component-78c5997874-s2hrs Total loading time: 0 Render date: 2024-11-18T04:29:54.319Z Has data issue: false hasContentIssue false
  • English
  • Français

Sodium metasomatism along the Melones Fault Zone, Sierra Nevada Foothills, California, USA

Published online by Cambridge University Press:  05 July 2018

George V. Albino
George V. Albino*
Affiliation:
Corona Gold Inc., 1375 Greg Street, Suite 105, Sparks, NV, 89431, USA
Get access Rights & Permissions [Opens in a new window]

Abstract

Albitite, locally aegirine- and riebeckite-bearing, formed as a result of sodium metasomatism of felsic dykes and argillites along the Melones Fault Zone near Jamestown, California. Pyrite, magnetite, hematite and titanite are common in small amounts in altered dykes. The dykes were originally plagioclase-hornblende porphyritic, and had major and trace element abundances typical of calc-alkaline rocks, whereas they now have Na2O contents as high as 11.40%. Associated fracture-filling veins are dominated by albite, but locally include aegirine, analcime, paragonite, calcite and sodic scapolite. Quartz is present in most albitic rocks, but is absent in riebeckite- and aegirine-bearing samples. Albitization predated CO2 metasomatism and formation of sericite-pyrite assemblages that are typical of gold deposits of the Mother Lode Belt.

Alkaline fluids responsible for Na-metasomatism had elevated Na+/K+ and Na+/H+ relatively high fO2, and low aH4SiO4. The presence of titanite indicates fluid. The presence of titanite indicates fluid XCO2 was low, in contrast to fluids that formed later carbonate-bearing assemblages. Sodic scapolite suggests that, at least locally, the fluids attained very high salinities.

Mass balance calculations indicate that alteration involved addition of large amounts of sodium, and the removal of SiO2 and K2O. Textural preservation, combined with volume factors calculated from specific gravity and whole rock analytical data, indicate that Na-metasomatism was essentially isovolumetric.

Sodium-rich zones along the Melones Fault Zone are closely associated with fault-bounded bodies of ultramafic rock, typically altered to talc-carbonate or quartz-magnesite-Cr muscovite assemblages. Carbonatization and talc-forming reactions in the ultramafic rocks may lead to SiO2-undersaturated fluids. Expansion of the muscovite stability field in terms of Na+/K+-Na+/H+, as a result of incorporation of Cr (up to 7.7% Cr2O3) in muscovite, would result in H+- and K+-depletion as the fluid interacts with ultramafic rocks. This could lead to fluids with elevated Na+/K+ and high pH, as documented in this occurrence.

Keywords

sodium metasomatismfault zoneSierra NevadaCalifornia
Type
Geochemistry
Information
Mineralogical Magazine , Volume 59 , Issue 396 , September 1995 , pp. 383 - 399
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1995

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Footnotes

*

Present address: U.S. Geological Survey, P.O. Box 1488, Jeddah 21431, Saudi Arabia

References

Albino, G.V. (1990) Structural setting, geochemistry, and large-scale metal zoning in Mother Lode-type deposits. Unpub. Ph.D. thesis, Univ. Western Ontario, London, Canada.Google Scholar
Albino, G.V. (1993) In Basement Tectonics, 7 (Mason, R., ed.), Kluwer, Amsterdam, 289-303.Google Scholar
Berman, R.G. (1988) Internally consistent thermody-namic data for minerals in the system Na2O-K2O-CaO-MgO-FeO-Fe2O3-Al2O3-SiO2-TiO2-H2O-CO2 . J. Petrol., 29, 445–522.CrossRefGoogle Scholar
Berman, R.G., Brown, T.H. and Perkins, E.H. (1987) GEO-CALC: Software for calculation and display of P-T-X phase diagrams. Amer. Mineral, 72, 861–2.Google Scholar
Bohlke, J.K. (1986) Local wall rock control of alteration and mineralization reactions along discordant gold quartz veins, Alleghany, California. Unpub. Ph.D. thesis, University of California, Berkeley, Berkeley, California.Google Scholar
Bohlke, J.K. (1989) Econ. GeoL, 84, 291–327.CrossRefGoogle Scholar
Bohlke, J.K. and Kistler, R.W. (1986) Econ. Geol. 81, 296–322.CrossRefGoogle Scholar
Card, K.D., Poulsen, K.H., and Robert, F. (1989) In The geology of gold deposits; the perspective in 1988 (Keays, R.R., Ramsay, W.R.H., and Groves, D.I., eds.) Economic Geology Monograph 6, 19–36.Google Scholar
Chidester, A.H. (1962) Petrology and geochemistry of selected talc-bearing ultramafic rocks and adjacent country rocks in north-central Vermont. U.S. Geol. Surv. Prof Pap. 345, 207 pp.Google Scholar
Clark, L.D. (1960) Geol. Soc. Am. Bull. 71, 483–96.CrossRefGoogle Scholar
Colvine, A.C. (1989) In The geology of gold deposits; the perspective in 1988 (Keays, R.R., Ramsay, W.R.H., and Groves, D.I., eds.) Economic Geology Monograph 6, 37–53.Google Scholar
Couture, J-F. and Pilote, P. (1993) Econ. Geol. 88, 1664-84.CrossRefGoogle Scholar
Coveney, R.M. Jr. (1981) Econ. Geol. 76, 2176–99.CrossRefGoogle Scholar
Francis, G. (1955) Geol. Mag. 92, 433–47.CrossRefGoogle Scholar
Garson, M.S., Coats, J.S., Rock, N.M.S., and Deans, T. (1984) Q. Jour. Geol. Soc. London, 141, 711–32.CrossRefGoogle Scholar
Gresens, R.L. (1967) Chem. Geol., 2, 47–65.CrossRefGoogle Scholar
Groves, D.I., Barley, M.E., and Ho, S.E. (1989) In The geology of gold deposits; the perspective in 1988 (Keays, R.R., Ramsay, W.R.H., and Groves, D.I., eds.) Economic Geology Monograph 6, 71–85.Google Scholar
Helgeson, H.C. (1969) Amer. J. Set, 267, 729–804.Google Scholar
Helgeson, H.C. and Kirkham, D.H. (1976) Amer. J. Sci., 276, 97–240.CrossRefGoogle Scholar
Helgeson, H.C, Delany, J.M., Nesbitt, H.W. and Bird, D.K. (1979) Amer. J. Sci., 278-A, 1-229.Google Scholar
Kerrich, R. (1983) Geochemistry of gold deposits in the Abitibi greenstone belt. Can. Inst. Mining and Metal. Special Paper 27, 75 pp.Google Scholar
Kishida, A. and Kerrich, R. (1987) Econ. Geol., 82, 649-90.CrossRefGoogle Scholar
Knopf, A. (1929) The Mother Lode system of California. U.S. Geol. Surv. Prof. Pap., 157.CrossRefGoogle Scholar
Lamarre, R.A. (1977) Geology of the Alabama-Crystalline Mines, Mother Lode gold belt, California. Unpub. M.Sc. thesis, University of Western Ontario, London.Google Scholar
Leake, B.E. (1978) Canad. Mineral, 16, 501–20.Google Scholar
Leonardos, O.H., Jr. and Fyfe, W.S. (1967) Amer. J. Sci., 265, 609–18.CrossRefGoogle Scholar
Lobato, L.M., Forman, J.M.A., Fuzikawa, K., Fyfe, W.S. and Kerrich, R. (1983a) Canad. Mineral, 21, 647–54.Google Scholar
Lobato, L.M., Forman, J.M.A., Fyfe, W.S., Kerrich, R. and Barnett, R.L. (19836) Nature, 303, 235–7.CrossRefGoogle Scholar
McLachlan, G.R. (1951) Mineral. Mag., 29, 476–95.Google Scholar
Masuda, A., Nakamura, N. and Tanaka, T. (1973) Geochim. Cosmochim. Ada, 37, 239–48.CrossRefGoogle Scholar
Miyano, T. and Klein, K. (1983) Amer. Mineral., 68, 517–29.Google Scholar
Morasse, S., Hodgson, C.J., Guha, J. and Coulombe, A. (1988) In Bicentennial gold 88; extended abstracts, poster programme (Goode, A.D.T., Smyth, E.L., Birch, W.D. and Bosma, L.I., eds.) . Abstracts, Geol. Soc. Austral, 23, 92–4.Google Scholar
Morogan, V. and Woolley, A.R. (1988) Contrib. Mineral. Petrol, 100, 169–82.CrossRefGoogle Scholar
Okay, A.I. (1980) J. Geol, 88, 225–32.CrossRefGoogle Scholar
Omel'yanenko, B.I. and Mineyeva, I.G. (1982) Inter. Geol. Rev., 24, 422–30.CrossRefGoogle Scholar
Papike, J.J. and White, C. (1979) Geophys. Res. Letters, 6, 913-16.CrossRefGoogle Scholar
Platt, R.G. and Woolley, A.R. (1990) Canad. Mineral, 28, 241-50.Google Scholar
Ransome, F.L. (1900) Description of the Mother Lode district [California]. U.S. Geol. Surv. Geol Atlas, Folio, 63.Google Scholar
Robinson, P., Spear, F.S., Schumacher, J.C., Laird, J., Klein, C, Evans, B.W. and Doolan, B.L. (1982) In Amphiboles: petrology and experimental phase relations (Veblen, D.R. and Ribbe, P.H., eds.) Rev. Mineral., 9B, 1-227.Google Scholar
Saleeby, IB., Geary, E.E., Paterson, S.R. and Tobisch, O.T. (1989) Geol. Soc. Amer. Bull, 101, 1481–92.2.3.CO;2>CrossRefGoogle Scholar
Taylor, B.E. (1986) In Gold ‘86, An International Symposium on the Geology of Gold Deposits, Poster Volume (Chater, A.M., ed.), 148-50.Google Scholar
Turner, H.W. (1896) Amer. Geol, 17, 375–86.Google Scholar
Vanko, D.A. and Bishop, F.C. (1982) Contrib. Min. Pet, 81, 277–89.CrossRefGoogle Scholar
Weir, R.H. Jr. and Kerrick, D.M. (1987) Econ. Geol, 82, 328–44.CrossRefGoogle Scholar
White, A.J.R. (1962) J. Petrol, 3, 38–48.CrossRefGoogle Scholar
Williams, H., Turner, F.J. and Gilbert, CM. (1982) Petrography; an introduction to the study of rocks in thin sections. W.H. Freeman and Company, San Francisco, 626 pp.Google Scholar