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Porphyritic-nodular, nodular, and orbicular chrome ores from the Sakhakot-Qila complex Pakistan, and their chemical variations

Published online by Cambridge University Press:  05 July 2018

Zulfiqar Ahmed
Zulfiqar Ahmed*
Affiliation:
Department of Geology, University of London, King's College, London WC2R 2LS
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Abstract

A new kind of chromitite texture—a porphyritic nodular texture, found in an alpine-type complex in Pakistan, is described. The chromite from phenocrystic nodules and that from their disseminated chromitite groundmass show comparable trivalent elements and postcumulus to subsolidus Mg−Fe2+ variations, which are also recorded from ‘normal’ nodular ore samples. The nodular ores differ from all other textural types of chromitite from this complex in an unusual, though slight, increase in Cr/(Cr+Al) with Mg/(Mg+Fe2+) between stratigraphically different desposits, which is caused by magmatic differences. The implications of major element variations in chromites and olivines of nodular chromirites are discussed and a cumulus origin is supported. Temperatures of final chromite-olivine equilibration ranged from 750 to 900 °C the individual nominal values being higher for chromitite with coarser chromite crystals and, or, higher chromite:silicate ratio.

Type
Research Article
Information
Mineralogical Magazine , Volume 45 , Issue 337 , 1982 , pp. 167 - 178
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1982

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Footnotes

*

Permanent address: Institute of Geology, University of the Punjab, New Campus, Lahore, Pakistan.

References

Ahmed, Z., and Hall, A. (1981) Chem. Erde, 40, 209-39.Google Scholar
Arai, S. (1978) Rep. Fac. Sci. Shizuoka Univ. 12, 99-113.Google Scholar
Arai, S. (1980) J. Petrol. 21, 141-65.CrossRefGoogle Scholar
Basu, A. R., and MacGregor, I. D. (1975) Geochim. Cosmochim. Acta, 39, 937-45.CrossRefGoogle Scholar
Bilgrami, S. A. (1964) Rec. Geol. Surv. Pakistan 10 (2C), 1–28.Google Scholar
Borchert, H. (1961) CENTO Symp. Chrome Ore, Ankara, 92-107.Google Scholar
Cassard, D., Rabinovitch, M., Nicolas, A., Moutte, J., Leblanc, M., and Prinzhofer, A. (1981) Econ. Geol. 76, 805-31.CrossRefGoogle Scholar
Clark, T. (1978) Can. J. Earth Sci. 15, 1893-1903.CrossRefGoogle Scholar
Deer, W. A., Howie, R. A., and Zussrnan, J. (1962) Rock Forming Minerals, vol. 5, Longmans, London.Google Scholar
Dickey, J. S. Jr., (1975) Geochim. Cosmochim. Acta, 39, 1061-74.CrossRefGoogle Scholar
Dickey, J. S. Jr., and Yoder, H. S. Jr., (1972) Carnegie Inst. Washington Yearb. 71, 384-92.Google Scholar
Evans, B. W., and Frost, B. R. (1975) Geochim. Cosmochim. Acta, 39, 959-72.CrossRefGoogle Scholar
Evans, B. W. and Wright, T. L. (1972) Am. Mineral. 57, 217-30.Google Scholar
Fabries, J. (1979) Contrib. Mineral. Petrol. 69, 329-36.CrossRefGoogle Scholar
Fujii, T. (1977) Carnegie Inst. Washington Yearb. 76, 563-9.Google Scholar
Greenbaum, D. (1977) Econ. Geol. 72, 1175-93.CrossRefGoogle Scholar
Hamlyn, P. R. (1980) Am. J. Sci. 280, 631-8.CrossRefGoogle Scholar
Hamlyn, P. R. and Keays, R. R. (1979) Contrib. Mineral. Petrol. 69, 75-82.CrossRefGoogle Scholar
Henderson, P. (1975) Geochim. Cosmochim. Acta, 39, 1035-44.CrossRefGoogle Scholar
Henry, D. J., and Medaris, L. G. Jr., (1980) Am. J. Sci. 280-A (the Jackson Volume), 211-31.Google Scholar
Himmelberg, G. R., and Loney, R. A. (1980) Ibid. 280-A, 232-68.Google Scholar
Irvine, T. N. (1965) Can. J. Earth Sci. 2, 648-72.CrossRefGoogle Scholar
Irvine, T. N. (1967) Ibid. 4, 71-103.Google Scholar
Jackson, E. D. (1969) In Magmatic Ore Deposits (Wilson, H. D. B., ed.), Econ. Geol. Mon. 4, 41-71.Google Scholar
Jackson, E. D. and Thayer, T. P. (1972) Proc. 24th Int. GeoL Congr. 2, 289-96.Google Scholar
Jan, M. Q., and Howie, R. A. (1981) J. Petrol. 22, 85-126.CrossRefGoogle Scholar
Johnston, W. D. Jr., (1936) Econ. Geol. 31, 417-27.CrossRefGoogle Scholar
Kaaden, G. v. d. (1963) Bull. Min. Res. Expl. Inst. Turkey, 61, 41-56.Google Scholar
Kaaden, G. v. d. (1970) Spec. Publ. Geol. Soc. S. Africa, 1, 511-31.Google Scholar
Keith, M. L. (1954) J. Am. Ceram. Soc. 37, 490-6.CrossRefGoogle Scholar
Leblanc, M. (1980) Mineral. Dep. 15, 201-10.CrossRefGoogle Scholar
Leblanc, M., Cassard, D., and Juteau, T. (1981) Ibid. 16, 269-82.Google Scholar
Malpas, J., and Strong, D. F. (1975) Geochim. Cosmochim. Acta, 39, 1045-60.CrossRefGoogle Scholar
Medaris, L. G. Jr., (1975) Ibid. 39, 947-58.Google Scholar
Mort, T. (1977) Contrib. Mineral. Petrol. 59, 261-79.CrossRefGoogle Scholar
Mukherjee, S. (1969) Econ. Geol. 64, 329-37.CrossRefGoogle Scholar
Oen, I. S., Kieft, C., and Westerhof, A. B. (1979) Ibid. 74, 1630-6.Google Scholar
Pavlov, N. V., Grigoryeva, I. I., and Tsepin, A. I. (1977) Int. Geol. Rev. 19 (1), 43–56.CrossRefGoogle Scholar
Ramp, L. (1957) Min. Engrg. 894-7.Google Scholar
Roeder, P. L., Campbell, I. H., and Jamieson, H. E. (1979) Contrib. Mineral. Petrol. 68, 325-34.CrossRefGoogle Scholar
Shams, F. A. (1964) Econ. Geol. 59, 1343-7.CrossRefGoogle Scholar
Snelgrove, A. K., and Ruotsala, A. P. (1968) Geol. Bull. Punjab Univ. 7, 31-42.Google Scholar
Stevens, R. E. (1944) Am. Mineral. 29, 1-34.Google Scholar
Thayer, T. P. (1960) Proc. 21st Int. Geol. Congr. Copenhagen, 13, 247-59.Google Scholar
Thayer, T. P. (1964) Econ. GeoL 59, 1497-524.CrossRefGoogle Scholar
Thayer, T. P. (1969) In Magmatic Ore Deposits (Wilson, H. D. B., ed.), Econ. Geol. Mon. 4, 132-46.Google Scholar
Thayer, T. P. (1970) Spec. Publ. Geol. Soc. S. Africa, 1, 380-90.Google Scholar
Zengin, Y. (1961) CENTO Symp. Chrome Ore, Ankara, 122-9.Google Scholar