Mineralium Deposita

, Volume 13, Issue 1, pp 11–26 | Cite as

Fractional crystallization and the origin of tin deposits in granitoids

  • D. I. Groves
  • T. S. McCarthy


A comparison between tin-bearing granitoids in an anorogenic setting (Bushveld Complex) and an orogenic setting (Blue Tier Batholith, Tasmania) reveals a number of genetically important similarities. These include: in situ fractional crystallization characterised by marked decrease in Ba and Sr and increase in Rb; the accumulation of late melt in a sheet-like form near the roof zone; the association of barren pegmatites overlying the ore; and of aplites; and the occurrence of conformable tin-bearing sheets, often exhibiting greisenization. These features allow the formulation of the following genetic model. A crustally-derived granitoid magma is emplaced and undergoes fractional crystallization from the margins inwards, with bottom crystallization dominating. Disruption of earlier formed solids by rest liquid commonly occurs. Continued fractional crystallization causes enrichment in volatiles and incompatible elements in the late rest melts, which have a sheet-like habit. The efficiency of enrichment of incompatible elements is critically dependant on the degree of separation of melt from solids throughout crystallization. An early, tin-poor vapour may separate after initial water-saturation of the magma is achieved, and this collects under the roof, commonly forming an impermeable barrier to later tin-bearing fluids. Continued fractional crystallization on the floor further enriches incompatible elements, and at a very late stage a Sn-rich vapour separates within the intercumulus phase and becomes concentrated by progressive crystallization of the intercumulus melt. At a late stage of solidification, this vapour loses equilibrium with the earlier formed feldspars and greisenization ensues, accompanied by the crystallization of cassiterite and other ore minerals. The nature of the mineralization changes if through-going fractures tap the late fluids. This model predicts systematic changes in trace element geochemistry with crystallization which provide useful tools for assessing the tin potential of a granitoid, and for indicating the direction of crystallization of the magma, and hence the location of possible ore.


Crystallization Fractional Crystallization Incompatible Element Bushveld Complex Trace Element Geochemistry 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Bailey, J. C.: Fluorine in granitic rocks: a review. Chem. Geol. 19, 1–42 (1977)Google Scholar
  2. Brooks, C.: The rubidium-strontium ages of some Tasmanian igneous rocks. J. geol. Soc. Aust. 13, 457–469 (1966)Google Scholar
  3. Brooks, C., Compston, W.: The age and initial 87Sr/86Sr of the Heemskirk Granite, Western Tasmania. J. Geophy. Res. 70, 6249–6262 (1965)Google Scholar
  4. Button, A.: Stratigraphy and relations of the Bushveld floor in the eastern Transvaal. Geol. Soc. S. Afr., Trans. 79, 1–12 (1976)Google Scholar
  5. Cousins, C. A.: The structure of the mafic portion of the Bushveld Igneous Complex. Geol. Soc. S. Afr. Trans. 62, 179–201 (1959)Google Scholar
  6. Davies, R. D., Allspp, H., Erlank, A. J., Manton, W. I.: Sr isotopic studies on various layered intrusions in southern Africa. Geol. Soc. S. Afr. Spec. Pub. 1., (editors D. J. L. Visser and G. von Gruenwaldt) 576–593 (1970)Google Scholar
  7. De Waal, S. A.: The Bushveld granites in the Zaaiplaats area. Geol. Soc. S. Afr. Trans. 75, 135–148 (1972)Google Scholar
  8. Fourie, P. J.: Die geochemie van granitiese gesteentes van die Bosveldstollingskompleks. Unpubl. D. Sc. Thesis. Univ. Pretoria. 289 pp (1969)Google Scholar
  9. Gee, R. D., Groves, D. I.: Structural features and mode of emplacement of part of the Blue Tier Batholith in north-east Tasmania. J. geol. Soc. Aust. 18, 41–56 (1971)Google Scholar
  10. Groves, D. I.: The geochemical evolution of tin-bearing granites in the Blue Tier Batholith, Tasmania. Econ. Geol. 67, 445–457 (1972a)Google Scholar
  11. - The zoned mineral deposits of the Scamander — St. Helens district. Geol. Surv. Tasm. Bull. 53, (1972b)Google Scholar
  12. - The geology, geochemistry and mineralization of the Blue Tier Batholith in The Blue Tier Batholith. Geol. Surv. Tasm. Bull. 55, (1977)Google Scholar
  13. Groves, D. I., Martin, E. L., Murchie, H., Wellington, H. K.: A century of tin mining at Mount Bischoff, 1871–1971. Geol. Surv. Tasm. Bull. 54, (1972)Google Scholar
  14. Groves, D. I., Taylor, R. G.: Greisenization and mineralization at Anchor tin mine, northeast Tasmania. Trans. Instn. Mining Metall. 82B, 135–146 (1973)Google Scholar
  15. Hamaguchi, H., Kuroda, R.: Tin in Handbook of Geochemistry. II-2. Berlin-Heidelberg-New York: Springer 1970Google Scholar
  16. Harris, P. G., Kennedy, W. Q. and Scarfe, C. M.: Volcanism versus plutonism — the effect of chemical composition. In Mechanism of igneous intrusion (Ed. G. Newall and N. Rast) 187–200 (1970)Google Scholar
  17. Hosking, K. F. G.: The primary tin deposits of South-east Asia. Min. Sci. Eng. 2, 24–50 (1970)Google Scholar
  18. Hunter, D. A.: Some enigmas of the Bushveld Complex. Econ. Geol. 71, 229–248 (1976)Google Scholar
  19. Hunter, D. R., Lenthall, D. H.: A preliminary review of tin mineralization with particular reference to the Bushveld Igneous Complex. Econ. Geol. Res. Unit. Univ. Wits. Inf. Circ. 61, (1971)Google Scholar
  20. Itsikson, M. I.: The distribution of tinore deposits within folded zones. Int. Geol. Rev. 2, 397–417 (1960)Google Scholar
  21. Jahns, R. H., Burnham, C. W.: Experimental studies of pegmatite genesis: I. A model for the derivation and crystallization of granitic pegmetities. Econ. Geol. 64, 843–864 (1969)Google Scholar
  22. Klomínský, J., Absolonová, E.: Geochemistry of the Karlovy Vary granite massif (Czechoslovakia). I. G. C. P. Symposium, M. A. W. A. M., 1, 189–196 (1974)Google Scholar
  23. Leaman, D. E., Symonds, P. A.: Gravity survey of North-eastern Tasmania. Geol. Surv. Tasm. Pap. 2, (1975)Google Scholar
  24. Liebenberg, L.: The sulphides in the layered sequence of the Bushveld Igneous Complex. Spec. Pub. Geol. Soc. S. Afr. (ed. D. J. L. Visser and A. van Gruenewaldt) 1, (1970)Google Scholar
  25. McCarthy, T. S.: The crystallization of a granitic melt as deduced from Ba distribution. Submitted to Trans. geol. Soc. S. Afr. (1977)Google Scholar
  26. McCarthy, T. S. and Groves, D. I.: The geology and geochemistry of the Blue Tier Batholith. In preparationGoogle Scholar
  27. McCarthy, T. S., Hasty, R. A.: Trace element distribution patterns and their relationship to the crystallization of granitic melts. Geochim. Cosmochim. Acta. 40, 1351–1358 (1976)Google Scholar
  28. McDougall, I., Leggo, P. J.: Isotopic age determinations on granitic rocks from Tasmania. J. geol. Soc. Aust. 12, 295–332 (1965)Google Scholar
  29. Mitchell, A. H. G., Garson, M. S.: Relationship of porphyry copper and circum-Pacific tin deposits to palaeo-Benioff zones. Trans. Instn. Mining Metall. 81B, 10–25 (1972)Google Scholar
  30. Reid, A. M., Henderson, Q. J.: Blue Tier tin field. Geol. Surv. Tasm. Bull. 38 (1928)Google Scholar
  31. Rhodes, R. C.: Petrochemical characteristics of Bushveld granite and Rooiberg felsite. Geol. Soc. S. Afr. Trans. 77, 93–98 (1974)Google Scholar
  32. Richards, J. R., White, D. A., Webb, A. W., Branch, C. D.: Isotopic ages of acid igneous rocks in the Cairns Hinterland, north Queensland. Bull. Bur. Min. Res. Aust. 88, (1966)Google Scholar
  33. Schuiling, R. D.: Tin belts on the continents around the Atlantic Ocean. Econ. Geol. 62, 540–550 (1967)Google Scholar
  34. Sillitoe, R. H., Halls, C., Grant, J. N.: Porphyry tin deposits in Bolivia. Econ. Geol. 70, 913–927 (1975)Google Scholar
  35. Solomon, M., Groves, D. I., Klomínský, J.: Metallogenic provinces and districts in the Tasman orogenic zone of eastern Australia. Proc. Australas. Inst. Mining Metall. 242, 9–24 (1972)Google Scholar
  36. Stemprok, M., Sulcek, Z.: Geochemical profile through an ore-bearing lithium granite. Econ. Geol., 64, 392–404 (1969)Google Scholar
  37. Strauss, C. A.: The geology and mineral deposits of the Potgietersrus Tinfields. Mem. Geol. Surv. S. Afr. 46, 241 pp. (1954)Google Scholar
  38. Strauss, C. A. and Truter, F. C.: The Bushveld granites of the Zaaiplaats Tin Mining area. Geol. Soc. S. Afr. Trans. 47, 47–78 (1944)Google Scholar
  39. Taylor, R. G.: Metallogenic provinces as an approach to the problems of classification and genesis of tin deposits with special reference to Eastern Australia. I. G. C. P. Symposium, M. A. W. A. M., 1, 71–79 (1974)Google Scholar
  40. — Porphyry tin deposits in Bolivia: Discussion. Econ. Geol. 71, 1064–1065 (1976)Google Scholar
  41. Thomas, D. E.: The Blue Tier tinfield in Edwards, A. B. (ed.): Geology of Australian ore deposits, 5th Emp. Mining Metall. Congr. 1, 1213–1221 (1953)Google Scholar
  42. Tischendorf, G.: The metallogenetic basis of tin exploration in the Erzgebirge. Trans. Instn. Mining Metall. 82B, 9–24 (1973)Google Scholar
  43. - Geochemical and petrographic characteristics of silicic magmatic rocks associated with rare element mineralization. I. G. C. P. Symposium, M. A. W. A. M., 2 (1977)Google Scholar
  44. Turneure, F. S.: The Bolivian tin-silver province. Econ. Geol. 66, 215–225 (1971)Google Scholar
  45. Van der Merwe, M. J.: The layered sequence of the Potgietersrus limb of the Bushveld Complex. Econ. Geol. 71, 1337–1351 (1976)Google Scholar
  46. Vermaak, C. F.: The geology of the lower portion of the Bushveld Complex and its relationship to the floor rocks in the area west of the Pilanesberg, western Transvaal. Spec. Pub. Geol. Soc. S. Afr. 1 (ed. D. J. L. Visser and A. von Gruenewaldt). 242–265 (1970)Google Scholar
  47. — The nickel pipes of Vlakfontein and vicinity, western Transvaal. Econ. Geol. 71, 261–286 (1976)Google Scholar
  48. Webb, E. A., McDougall, I.: The geochronology of the igneous rocks of Eastern Queensland. J. geol. Soc. Aust. 15, 313–346 (1968)Google Scholar
  49. Willemse, J.: A brief outline of the geology of the Bushveld Igneous Complex. In Haughton, S. H. The geology of some ore deposits in southern Africa. Geol. Soc. S. Afr. 2, 91–128 (1964)Google Scholar
  50. — The geology of the Bushveld Igneous Complex, the largest repository of magmatic ore deposits in the world. In: Wilson, H. D. B. ed. Magmatic ore deposits: Econ. Geol. Mem. 4, 1–22 (1969)Google Scholar
  51. Wolhuter, L. E.: Major and trace elements in the Opemisca Lake granite pluton, Quebec, Canada. Geol. Soc. S. Afr. Spec. Pub. 3, 387–410 (1973)Google Scholar

Copyright information

© Springer-Verlag 1978

Authors and Affiliations

  • D. I. Groves
    • 1
  • T. S. McCarthy
    • 1
  1. 1.Department of GeologyUniversity of the WitwatersrandJohannesburgSouth Africa

Personalised recommendations