Hostname: page-component-78c5997874-m6dg7 Total loading time: 0 Render date: 2024-11-11T14:00:35.218Z Has data issue: false hasContentIssue false
  • English
  • Français

Compositional variation in chromite from the Eastern Desert, Egypt

Published online by Cambridge University Press:  05 July 2018

Ali A. Khudeir ,
Mervet A. El Haddad  and
Bernard E. Leake
Ali A. Khudeir
Affiliation:
Department of Geology, University of Assiut, Assiut, Egypt
Mervet A. El Haddad
Affiliation:
Department of Geology, University of Assiut, Assiut, Egypt
Bernard E. Leake
Affiliation:
Department of Geology and Applied Geology, University of Glasgow, G12 8QQ, U.K.
Get access Rights & Permissions [Opens in a new window]

Abstract

Electron microprobe analyses of chromite ores from Baramiya, Seifein, Siwigat, Ashayer, Um Salatit and Ras Shait, Egypt, reveal two compositional groups. The unaltered chromites from Baramiya and Seifein have high Al and low Cr contents [Cr/(Cr + Al) = 0.56] whereas the remainder have low Al and high Cr contents [Cr/(Cr + Al) = 0.73]. Such bimodality characterises Alpine-type peridotites. The second group probably crystallised at higher T and lower P than the first group and has a composition characteristic of a type III alpine-type peridotite, i.e. of arc or possibly ocean plateau origin but not of mid-ocean ridge origin. The crystallisation setting of the first group is less certain but not inconsistent with the same environment as the second group so that considering the likely higher pressure of crystallisation of the first group overall favours plutonic crystallisation in the roots of an arc for both groups.

Rim, patchy and fracture alteration of the chromite occurred possibly partly of late magmatic (deuteric) origin but mainly connected with fluid movements, serpentinisation and tectonism. The final composition of the resultant ferritchromite is variable and depends largely on the original chromite composition; the composition of the ferritchromite developed in highly cataclased chromites deviates markedly from that of the original chromite presumably due to unmixing and migration.

Keywords

chromiteferritchromiteEastern DesertEgypt
Type
Research Article
Information
Mineralogical Magazine , Volume 56 , Issue 385 , December 1992 , pp. 567 - 574
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1992

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.)

References

Aria, M. S., and Iman, I. (1979) Mineral map of Egypt, Scale 1:2000000, with explanatory notes and lists. Geol. Surv. Egypt., 44P.Google Scholar
Amin, M. S. (1948) Origin and alteration of chromites from Egypt. Econ. Geol., 43, 133–53.CrossRefGoogle Scholar
Anwar, Y., Kotb, H., and Zohny, N. (1969) Geo-chemistry of Egyptian chromites. Bull. Fac. Sci., Alex. Univ., Alex. Egypt, 142-82.Google Scholar
Basta, E. Z. and Hanafy, M. A. (1970) Alteration of some Egyptian chromites. Proc. Egypt. Acad. Sci., 23, 1–7.Google Scholar
Beeson, M. H. and Jackson, E. D. (1969) Chemical composition of altered chromites from the Still-water Complex, Montana, Amer. Mineral., 54, 1084–1100.Google Scholar
Bryan, W. B. (1972) Mineralogical studies of submarine basalts: Carnegie Inst. Wash. Yearb., 71, 394–402.Google Scholar
Dick, H. J. B. and Bullen, T. (1984) Chromian spinel as a petrogenetic indicator in abyssal and alpine-type peridotites and spatially associated lavas. Contrib. Mineral Petrol., 85, 54–76.CrossRefGoogle Scholar
Dick, H. J. B. and Bullen, T. and Fisher, R. L. (1983) Mineralogic studies of the residues of mantle melting. Proceedings 3nd International kimberlite Conference. Developments in Petrology Series, Elsevier.CrossRefGoogle Scholar
El-Gaby, S., List, F. K. and Tehrani, R. (1988) Geology, evolution and Metallogenesis of the Pan-African belt in Egypt: In The Pan African Belt of Northeast Africa and Adjacent areas, Viewegverlag. (S. El-Gaby and R. D. Greiling, eds).Google Scholar
El-Haddad, M. A. and Khudeir, A. A. (1989) Geological and geochemical studies on some chromite deposits in the Central Eastern Desert, Egypt. Bull. Fac. Sci.,Assiut Univ., 13 (l-F), 141-58.Google Scholar
El-Sharkawi, M. A. and El-Bayoumi, R. (1979) The ophiolites of Wadi Ghadir, E. D., Egypt. Annals Geol. Surv. Egypt, 9, 12535.Google Scholar
Engin, E. and Aucott, J. W. (1971) A microprobe study of chromites from the Andizlik-Zimparalik area, south-west Turkey, Mineral. Mag., 38, 76–82.CrossRefGoogle Scholar
Frey, F. A. Bryan, W. B. and Thompson, G. (1974) Atlantic Ocean floor: Geochemistry and petrology of basalts from legs 2 and 3 of the Deep-Sea Drilling Project. J. Geophys. Res., 79, 5507–27.CrossRefGoogle Scholar
Hutchison, C. S. (1972) Alpine-type chromite in north Borneo, with special reference to Darvel Bay. Am. Mineral., 37, 835–56.Google Scholar
Irvine, T. N. (1967) Chromian spinel as a petrogenic indicator, Part 2, Petrologic applications. Canad. J. Earth Sci. 4, 71–103.CrossRefGoogle Scholar
Jan, Q. M. and Windley, B. F. (1990) Chromian spinel-silicate chemistry in ultramafic rocks of the J. ijal complex, NW Pakistan. J. Petrol., 31, 667–715.CrossRefGoogle Scholar
Ozawa, K. (1983) Evaluation of olivine-spinel geother-mometry as an indicator of thermal history for peridotites. Contrib. Mineral. Petrol., 82, 52–65.CrossRefGoogle Scholar
Ries, A. C., Shackleton, R. M., Graham, R. H., and Fitches, W. R. (1983) Pan-African structures, ophiolites and melange in the Eastern Desert of Egypt: a traverse at 261 J. geol. Soc. Lond., 140, 75–96.CrossRefGoogle Scholar
Stevens, R. E. (1944) Composition of some chromites of the Western hemisphere Am. Mineral., 29, 1–34.Google Scholar
Takla, M. A. (1982) Chromites from the Bergen arcs ultramafics, southern Norway, Neues Jahrb. Mineral., Abh, 144, 56–72.Google Scholar
Takla, M. A. and Noweir, A. M. (1980) Mineralogy and mineral chemistry of the ultramafic mass of E1-Rubshi, Eastern Desert, Egypt. Ibid., 140, 17–28.Google Scholar
Thayer, T. P. (1970) Chromite segregations as petro-genetic indicators, Geol. Soc. S. Africa, Spec. Publ. 1, 380-90.Google Scholar
Zakrzewski, M. A. (1989) Chromian spinels from Kusa, Bergslagen, Sweden. Am. Mineral., 74, 448–55.Google Scholar