Skip to main content Accessibility help
×
Home

Micas of the muscovite–lepidolite series from Karibib pegmatites, Namibia

  • E. Roda (a1), P. Keller (a2), A. Pesquera (a1) and F. Fontan (a3)

Abstract

Micas of the muscovite–lepidolite series are main constituents of the evolved pegmatites from the Okatjimukuju-Kaliombo portion of the Karibib belt, Namibia. The compositional variations shown by the micas from the intermediate zones are mainly controlled by the Li3Al-1-2 and SiLi2Al-2-1 substitution schemes, whereas for the micas from the core margins and the replacement bodies, only the first of these two exchange vectors seems to operate. The chemical composition of the micas not only depends on the degree of pegmatite evolution, but also on the position in the internal zonation of the pegmatite. Micas from the core margins and the replacement units are generally richer in F, Li, Rb, Cs and Zn than those from the intermediate zones. In general, the contents of these elements increase with decreasing K/Rb ratio. However, some data departing from this general trend are also observed, which could be related to subsolidus processes. Some pegmatite bodies show a complete internal evolution, developed from the margins to the core zone, which is reflected in the chemical composition of the micas. The regional distribution of pegmatites does not define a zonation, because an overlapping of pegmatites with different degrees of evolution occurs. This could be due to the high level of evolution attained by most of the rare-element pegmatites, and to their topography with respect to a dome structure of the basement.

Copyright

Corresponding author

References

Hide All
Appleman, D.E. and Evans, H.T. Jr., (1973) Job 9214: Indexing and least-squares refinement of powder diffraction data. US Geological Survey. The National Technical Information Service, PB2–16188.
Bailey, S.W. (1980) Structures of layer silicates. Pp. 1–39.in: Crystal Structures of Clay Minerals and their X-ray Identification (Brindley, G.W. and Brown, G., editors). Monograph 5, Mineralogical Society, London.
Banadina, E.V., Veksler, I.V., Thomas, R., Syritso, L.F. and Trumbull, R.B. (2004) Magmatic evolution of Li-F, rare-metal granites: a case study of melt inclusions in the Khangilay complex, Eastern Transbaikalia (Russia). Chemical Geology, 210, 113–134.
Bau, M. (1996) Controls on the fractionation of isovalent trace elements in magmatic and aqueous systems; evidence from Y/Ho, Zr/Hf, and lanthanide tetrad effect. Contributions to Mineralogy and Petrology, 123, 323–333.
Brigatti, M.F., Lugli, C, Poppi, L., Foord, E.E. and Kile, D.E. (2000) Crystal chemical variations in Li- and Fe-rich micas from Pikes Peak Batholith (central Colorado). American Mineralogist , 85, 1275–1286.
Černy, P. (2004) The Tanco rare-element pegmatite deposit, Manitoba: regional context, internal anat-omy, and global comparisons. Pp. 184–231 in: Rare Element Geochemistry and Ore Deposits (Linne, R.L. and Samson, I.M., editors). Short Course Notes, 17, Geological Association of Canada.
Černy, P. and Burt, D.M. (1984) Paragenesis, crystallo-chemical characteristics, and geochemical evolution of micas in granite pegmatites. Pp. 257–297 in: Micas (Bailey, S.W., editor). Reviews in Mineralogy, 13, Mineralogical Society of America, Washington, D.C.
Černy, P., Trueman, D.L., Ziehlke, D.V., Goad, B.E. and Paul, B.J. (1981) The Cat Lake-Winnipeg River and the Wekusko Lake pegmatite fields, Manitoba. Manitoba Mineral Research Division, Economic Geology Report, ER 801, 240 pp.
Černy, P., Ercit, T.S. and Vanstone, P.J. (1998) Mineralogy and petrology of the Tanco rare-element pegmatite deposit, Southeastern Manitoba. IMA 17th General Meeting (Toronto), Field Trip Guide Book.
Clarke, D.B. and Bogutyn, P.A. (2003) Oscillatory epitactic-growth zoning in biotite and muscovite from the Lake Lewis leucogranite, South Mountain batholith, Nova Scotia, Canada. The Canadian Mineralogist, 41, 1027–1047.
Corner, B. (1983) An interpretation of the aeromagnetic data covering the western portion of the Damara Orogen in South West Africa/Namibia. Special Publications Geological Society of South Africa. 58, 46–70.
Diehl, , (1993) Pegmatites of the Cape Cross-Uis pegmatite belt, Namibia: geology, mineralisation, rubidium-strontium characteristics and petrogenesis. Journal of African Earth Sciences, 17, 167–181.
Foord, E.E., Černy, P., Jackson, L.L., Sherman, D.M. and Eby, R.K. (1995) Mineralogical and geochemical evolution of micas from miarolitic pegmatites of the anorogenic Pikes Peak batholith, Colorado. Mineralogy and Petrology, 55, 1–26.
Foster, M.D. (1960) Interpretation of the composition of Li-micas. US Geological Survey, Professional Paper , 354 E, M.A. 15–263.
Frommurze, H.F., Gevers, TW. and Rossouw, P.J. (1942) The geology and mineral deposits of the Karibib area, South West Africa. Explanatory Sheet, 79 (Karibib S.W.A.). Geological Survey of South Africa, 172 pp.
Gaupp, R., Möller, P. and Morteani, G. (1984) Tantal-pegmatite. Geologische, Petrologische und Geochemische Untersuchungen Monograph Series on Mineral Deposits , 23, Gebriider Borntraeger-Berlin-Stuttgart, 124 pp.
Gevers, T.W. (1963) Geology along the north-western margin of the Khomas Highlands between Otjimbingwe-Karibib and Okahandja, South West Africa. Transactions of the Geological Society of South Africa, 66, 199–251.
Goad, B.E. and Černy, P. (1981) Peraluminous pegmatitic granites and their pegmatite aureoles in the Winnipeg River district, Southeastern Manitoba. The Canadian Mineralogist, 19, 177–194.
Henderson, C.M.B., Martin, J.S. and Mason, R.A. (1989) Compositional relations in Li-micas from S.W. England and France: an ion- and electron-microprobe study. Mineralogical Magazine, 53, 427–449.
Jolliff, B.L., Papike, JJ. and Shearer, C.K. (1987) Fractionation trends in mica and tourmaline as indicators of pegmatite internal evolution: Bob Ingersoll pegmatite, Black Hills, South Dakota. Geochimica et Cosmochimica Acta, 51, 519–543.
Jolliff, B.L., Papike, JJ. and Shearer, C.K. (1992) Petrogenetic relationships between pegmatite and granite based on geochemistry of muscovite in pegmatite wall zones, Black Hills, South Dakota, USA. Geochimica et Cosmochimica Acta, 56, 1915–1939.
Kamenetsky, V.S., Naumov, V.B., Davidson, P., van Achterbergh, E. and Ryan, C.G. (2004) Inmiscibility between silicate magmas and saline fluids: a melt inclusion microprobe into magmatic-hydrothermal transition in the Omsukchan Granite (NE Russia). Chemical Geology, 210, 73–90.
Keller, P. (1991) The occurrence of Li-Fe-Mn phosphate minerals in granitic pegmatites of Namibia. Communnications of the Geological Survey of Namibia, 7, 21–34.
Keller, P. and Von Knorring, O. (1989) Pegmatites at the Okatjimukuju farm, Karibib, Namibia. Part I: Phosphate mineral associations on the Clementine II pegmatite. European Journal of Mineralogy, 1, 567–593.
Kile, D.E. and Foord, E.E. (1998) Micas from the Pikes Peak Batholith and its cogenetic granitic pegmatites, Colorado: optical properties, composition, and correlation with pegmatite evolution. The Canadian Mineralogist, 36, 463–482.
Miller, R.McG. (1983a) Economic implications of plate tectonic models of the Damara orogen. Geological Society of South Africa, Special Publications , 11, 385–395.
Miller, R.McG. (19836) The pan-African Damara orogen of South West Africa/Namibia. Geological Society of South Africa Special Publications, 11, 431–515.
Miller, R.McG. (1992) Mineral exploration targets in Namibia. Pp. 1–5 in: The Mineral Resources of Namibia (Hoal, B.G., editor). Geological Survey of Namibia, Windhoek, Namibia.
Monier, G. and Robert, J.L. (1986) Evolution of the miscibility gap between muscovite and biotite solid solutions with increasing lithium content: and experimental study in the system K2O-Li2O-MgO-FeO-Al2O3-SiO2-H2O-HF at 600°C, 2 kbar PH O:comparison with natural lithium micas. Mineralogical Magazine, 50, 641–651.
Morteani, G. and Gaupp, R. (1986) Geochemical evaluation of the tantalum potential of pegmatites. In: Special Publication No. 7 of the Society for Geology Applied to Mineral Deposits (Möller, P. Černy, P. and Saupé, F., editors). Springer Verlag, Berlin.
Oliver, G.J. (1995) The Central zone of the Damara orogen, Namibia, as a deep metamorphic core complex. Communications of the Geological Survey of Namibia, 10, 33–41.
Pesquera, A., Torres-Ruiz, J., Gil-Crespo, P. and Velilla, N. (1999) Chemistry and genetic implications of tourmaline and Li-F-Cs micas from the Valdeflores area (Cáceres, Spain). American Mineralogist, 84, 55–69.
Robert, J.L., Bény, J.M., Bény, C. and Volfmger, M. (1989) Characterization of lepidolites by Raman and Infrared spectrometries. I. Relationships between OH-stretching wavenumbers and composition. The Canadian Mineralogist, 27, 225–235.
Robert, J.L., Bény, J.M., Delia Ventura, G. and Hardy, M. (1993) Fluorine in micas: crystal-chemical control of the OH-F distribution between trioctahe-dral sites. European Journal of Mineralogy, 5, 7–18.
Roda, E., Pesquera, A. and Velasco, F. (1995) Micas of the muscovite-lepidolite series from the Fregeneda pegmatites (Salamanca, Spain). Mineralogy and Petrology, 55, 145–157.
Roda, E., Pesquera, A., Gil-Crespo, P.P., Torres-Ruiz, J and Fontan, F. (2005) Origin and internal evolution of the Li-F-Be-B-P-bearing Pinilla de Fermoselle pegmatite (Central Iberian Zone, Zamora, Spain). American Mineralogist, 90, 1887–1899.
Roda, E., Pesquera, A., Gil-Crespo, P.P., Torres-Ruiz, J. and de Parseval, P. (2006) Mineralogy and geochemistry of micas from the Pinilla de Fermoselle pegmatite (Zamora, Spain). European Journal of Mineralogy, 18, 369–377.
Roering, C. and Gevers, T.W. (1964) Lithium- and beryllium-bearing pegmatites in the Karibib district, South West Africa. Pp. 463–496 in: The Geology of some Ore Deposits in Southern Africa Vol. 2 (Haughton, S.H., editor). Geological Society of South Africa.
Steven, N.M. (1993) A study of epigenetic mineralization in the Central Zone of the Damara Orogen, Namibia, with special reference to gold, tungsten, tin and rare earth elements. Geological Survey of Namibia, Memoir 16, 166 pp.
Tack, L. and Bowden, P. (1999) Post-collisional granite magmatism in the Central Damara (Pan-African) orogenic belt, western Namibia. Journal of African Earth Sciences, 28, 653–674.
Thomas, R., Webster, J.D. and Heinrich, W. (2000) Melt inclusions in pegmatite quartz: complete miscibility between silicate melts and hydrous fluids at low pressure. Contributions to Mineralogy and Petrology, 139, 394–401.
Tindle, A.G. and Webb, P.C. (1990) Estimation of lithium contents in trioctahedral micas using micro-probe data: application to micas from granitic rocks. European Journal of Mineralogy, 2, 595–610.
Tischendorf, G., Gottesmann, B., Förster, HJ. and Trumbull, R.B. (1997) On Li-bearing micas: estimating Li from electron microprobe analyses and an improved diagram for graphical representa-tion. Mineralogical Magazine, 61, 809–834.
Tischendorf, G., Rieder, M., Förster, H.J., Gottesmann, B. and Guidotti, C.V. (2004) A new graphical representation and subdivision of potassium micas. Mineralogical Magazine, 68, 649–667.
Varlamov, N. (1958) Zoneographie de quelques champs pegmatitiques de PAfrique Central et les classifica- sions de K.A. Vlassov et de A.I. Ginsbourg. Annales de la Societe Geologique Beige , D82, 55–87.
Veksler, I.V. (2004) Element enrichment and fractiona-tion by magmatic aqueous fluids: experimental constraints on melt-fluid inmiscibility and element partitioning. Pp. 103–129 in: Rare Element Geochemistry and Ore Deposits (Linne, R.L. and Samson, I.M., editors). Short Course Notes, 17, Geological Association of Canada.
Von Knorring, O. (1985) Some mineralogical, geo-chemical and economic aspects of lithium pegmatites from the Karibib-Cape Cross pegmatite field in South Wst Africa/Namibia. Communications of the Geological Survey of SW Africa/Namibia, 1, 79–84.
Wise, M.A. (1995) Trace element chemistry of lithium-rich micas from rare-element granitic pegmatites. Mineralogy and Petrology, 55, 203–215.

Keywords

Micas of the muscovite–lepidolite series from Karibib pegmatites, Namibia

  • E. Roda (a1), P. Keller (a2), A. Pesquera (a1) and F. Fontan (a3)

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed