Textural features and chemical characteristics of chromites in ultramafic rocks, Chalkidiki Complex (Northeastern Greece)
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Summary
The lower ultramafic part of the Chalkidiki Ophiolite Complex consists of a successive alternation of chromitite, dunite, and harzburgite, which is repeated periodically in a cyclic manner. This cyclic pattern is consistent with an origin as magmatic cumulates. However, the tectonic fabric superimposed on the cumulate texture of this sequence suggest a solid-state deformation at considerable depth.
In the present study, the textural and chemical features of chromite are discussed. The interrelationships between the compositions of chromite, its mode of occurrence as well as the associated silicates are emphasized. It is found that the investigated chromites have properties in common with both podiforn and stratiform chromites. From a geometrical and structural point of view, they are of podiform type. On the other hand, their appreciably high iron content, the strong interdependence between the composition of chromite and the coexisting silicates together with the cryptic layering exhibited by the two mineral groups contrast markedly with podiform chromites.
An alternative hypothesis is proposed involving fractional crystallization of an ultrabasic melt introduced to the magma chamber as periodic inflows of essentially the same composition. An upwelling upper-mantle that is subjected to stepwise partial fusion may fulfill these conditions.
Keywords
Chromite Textural Feature Magma Chamber Ultramafic Rock High Iron ContentChemismus und Texturen von Chromiten in ultramafischen Gesteinen des Chalkidiki Komplexes, Nordost-Griechenland
Zusammenfassung
Der untere, ultramafische Teil des Chalkidiki Komplexes besteht aus einer wechselnden Abfolge von Chromititen, Duniten und Harzburgiten, die sich zyklisch wiederholt. Diese zyklische Abfolge ist in guter Übereinstimmung mit einer Entstehung als magmatische Kumulate. Das tektonische Gefüge, das auf die Kumulat-Texturen überprägt wurde, weist jedoch auf Deformationen in festem Zustand in beträchtlicher Tiefe hin.
Die vorliegende Untersuchung befaßt sich mit dem Chemismus und den Texturen der Chromite. Besonderes Interesse wendet sich dabei den Wechselbeziehungen zwischen den Zusammensetzungen, der Art des Vorkommens und den assoziierten Silikaten zu. Dabei zeigt sich, daß die untersuchten Chromite in vieler Hinsicht Ähnlichkeiten sowohl mit podiformen wie mit stratiformen Vorkommen erkennen lassen. Geometrisch und texturell gesehen gehören sie dem podiformen Typ an. Nicht in Einklang damit stehen jedoch die beträchtlichen Eisengehalte sowie die deutlichen Wechselbeziehungen zwischen der Zusammensetzung von Chromit und der koexistierenden Silikate, und schließlich auch der kryptische Lagenbau, den die zwel Mineralgruppen erkennen lassen. Ein genetisches Modell wird vorgeschlagen, das fraktionierte Kristallisation einer ultrabasischen Schmelze von im wesentlichen gleichmäßiger Zusammensetzung vorsieht, die in periodischen Abständen der Magmenkammer zugeführt wurde. Eine Aufwölbung des oberen Mantels, die schrittweiser, partieller Aufschmelzung ausgesetzt ist, könnte diesen Bedingungen entsprechen.
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References
- Ahmed, Z., 1978: Chromite from Sakhakot-Qila area, Malakand Agency, Pakistan. Min. Mag.42, 155–157.Google Scholar
- Bateman, J. D., 1945: Composition of the Bird River chromite, Manitoba. Amer. Min.30, 596–600.Google Scholar
- Beeson, M. H., Jackson, E. D., 1969: Chemical composition of altered chromites from the Stillwater Complex, Montana. Amer. Min.,54, 1084–1100.Google Scholar
- Bilgrami, S. A., 1969: Geology and chemical mineralogy of the Zhob Valley chromite deposits, West Pakistan. Amer. Min.,54, 134–148.Google Scholar
- Burgath, K., 1980: Zur Petrologie und Prospektion alpinotyper Chromitvererzungen anhand griechischer Beispiele. Unpubl Report. Bundesanst. für Geowiss. und rohstoffe (Hannover). NTS-61, Vol. 2, pt. 2, 132p.Google Scholar
- Burgath, K., Weiser, Th., 1979: Primary features and genesis of Greek podiform chromite deposits. Proc. Int. Ophiolite Symp., Nicosia, pp. 675–690.Google Scholar
- Burgath, K., Grisseman, Ch., Herr, W., Johannes, W., Jung, D., Knölke, H., Kockel, F., Makris, J., Mohr, M., Mussallam, K., Raschka, H., 1980: On the genesis of magnesite deposits in Northern Greece. Proc. Int. Symp. Metal. Maf. Ultramaf. Complexes, Athens. (In press.)Google Scholar
- Cameron, E. N., 1970: Compositions of certain coexisting phase in the eastern part of the Bushveld Complex. Geol. Soc. South Africa, Spec. Publ1, 46–58.Google Scholar
- , 1975: Postcumulus and subsolidus equilibration of chromite and coexisting silicates in the eastern Bushveld Complex. Geochim. Cosmochim. Acta39, 1021–1033.Google Scholar
- , 1977: Chromite in the central sector of the eastern Bushveld Complex, South Africa, Amer. Min.,62, 1082–1096.Google Scholar
- 1978: The Lower Zone of the eastern, Bushveld Complex in the Olifants River trough. J. Petrol.19, 437–462.Google Scholar
- , 1980: Evolution of the Lower Critical Zone, central sector, eastern Bushveld Complex, and its chromite deposits. Econ. Geol.75, 845–871.Google Scholar
- , 1959: The origin of certain chromite deposits of the eastern part of the Bushveld Complex. Econ. Geol.54, 1151–1213.Google Scholar
- Chakraborty, K. L., 1973: Some characters of the bedded chromite deposits at Kalrangi, Cuttack district, Orissa, India. Min. Deposita8, 83–80.Google Scholar
- , 1971: Mineralogy, chemical composition and genesis of the chromite deposits of Moulabhanja area, Dmenkanal District, Orissa. J. Geol. Soc. India12, 135–141.Google Scholar
- Challis, G. A., 1965: The origin of New Zealand ultramafic intrusions. J. Petrol.6, 322–364.Google Scholar
- Dickey, J. S. Tr., 1965: A hypothesis of origin for podiform chromite deposits. Geochim. Cosmochim. Acta39, 1061–1074.Google Scholar
- Engin, T., Aucott, J. W., 1971: A microprobe study of chromites from the Andizlik. Zimparalik area, south-west Turkey. Min. Mag.,38, 76–82.Google Scholar
- England, R. N., Davies, H. L., 1973: Mineralogy of ultramafic cumulates and tectonites, from eastern Papua. Earth Planet. Sci. Let.73, 416–423.Google Scholar
- Fuchs, L. H., 1965: Examination of two chromite specimens from Kondapalle, India. Econ. Geol.60, 633–539.Google Scholar
- Golding, H. G., Johnson, K. R., 1971: Variation in gross chemical composition and related physical properties of podiform chromite in the Coolac district, N.S.W., Australia. Econ. Geol.66, 1017–1027.Google Scholar
- , 1968: Altered chrome ores from the Coolac serpentine belt, New South Wales, Australia. Amer. Min.53, 162–183.Google Scholar
- Green, D. H., 1963: Alumina content of enstatite in a Venezuelan high-temperature peridotite. Bull. Geol. Soc. Amer.74, 1397–1402.Google Scholar
- Greenbaum, D., 1977: The chromitiferous rocks of the Troodos Ophiolite Complex, Cyprus. Econ. Geol.,72, 1175–1194.Google Scholar
- Guild, P. W., 1947: Petrology and structure of the Moa district, Oriente provinces, Cuba. Amer. Geophys. Union Trans.28, 218–246.Google Scholar
- Henderson, P., 1975: Reaction trends shown by chrome-spinels of the Rhum layered intrusions. Geochim Cosmochim. Acta39, 1035–1044.Google Scholar
- , 1971: The nature and origin of the chrome-spinel of the Rhum layered intrusion. Contr. Min. Petrol.33, 21–31.Google Scholar
- Howland, A. L., 1955: Chromite deposits in the central part of the Stillwater Complex, Sweet Grass County, Montana. U.S. Geol. Surv. Bull. 1015-D, 99–121.Google Scholar
- , 1949: Chromite deposits of the Boulder River area, Sweetgrass Country Montana. U.S. Geol. Surv. Bull. 948-D, 63–82.Google Scholar
- Hutchinson, C. S., 1972: Alpine-type chromite in North Borneo, with special reference to Darvel Bay. Amer. Min.57, 835–856.Google Scholar
- Irvine, T. N., 1965: Chromian spinel as a petrogenetic indicator, Part I. Theory. Can. J. Earth Sci.,2, 648–672.Google Scholar
- , 1967: Chromian spinel as a petrogenetic indicator, Part 2. Petrologic applications. Can. J. Earth Sci.4, 71–103.Google Scholar
- , 1972: Alpine-type peridotite with particular reference to the Bay of Islands complex. Publ. Can. Dept. Energ. Mines Res. Earth Phys. Branch42, 97–129.Google Scholar
- Jackson, E. D., 1961: Primary textures and mineral associations in the ultramafic zone of the Stillwater Complex. U.S. Geol. Surv. Prof. Pap.358, 106 p.Google Scholar
- Jackson, E. D., 1968: The chromite deposits of the Stillwater Complex, Montana. In: Ore deposits of the United States, 1933–1967 (J. D. Ridge, ed.), pp. 1495–1510.Google Scholar
- Jackson, E. D., 1969: Chemical variation in coexisting, chromite and olivine in the chromitite zone of the Stillwater Complex. In: Magmatic ore deposits (Wilson, H. D. B., ed.), pp. 41–75.Google Scholar
- , 1975: The Vourinos ophiolite, Greece: Cyclic units of lineated cumulates overlaying harzburgite tectonite. Geol. Soc. Amer. Bull.86, 390–398.Google Scholar
- Jung, D., Mussallam, K., 1980: Geologische Stellung, Petrographie und Geochemie der Ophiolite Nordgriechenlands. Unpubl. Report, Bundesanst. für Geowiss. und Rohstoffe (Hannover), NTS-61, Vol. 2, pt. 1, 86 p.Google Scholar
- Jung, D., Mussallam, K., Burgath, K., Kockel, F., Mohr, M., Raschka, H., 1980: Ultramafic and related rocks of Chalkidiki. Proc. Int. Symp. Metal. Maf. Ultramaf. Complexes, Athens. (In press.)Google Scholar
- Jung, D., Mussallam, K., Burgath, K., Kockel, F., Mohr, M., Raschka, H., 1979: Mineralogy and geochemistry of the Chalkidiki mafic-ultramafic rocks. Internat. Ophiolite Symposium, Abstracts, Cyprus Geol. Surv. Dept., pp. 40–41.Google Scholar
- Kaaden, G. V. D., 1970: Chromite-bearing ultramafic and related gabbroic rocks and their relationship to ophiolitic extrusive rocks and diabases in Turkey. Geol. Soc. S. Africa, Special Publ.,1, 511–531.Google Scholar
- Kockel, F., Mollat, H., Walther, H. W., 1971: Geologie des Serbomazedonischen Massivs und seines mesozoischen Rahmens (Nordgriechenland). Geol. Jb.89, 529–551.Google Scholar
- , 1972: Die Magnesitvererzung in der westlichen Chalkidiki (Griechisch-Mazedonian). Bundesanst. f. Geowiss. und Rohstoffe, Hannover, 86 p.Google Scholar
- MacGregor, I. D., Smith, C. H., 1963: The use of chrome spinels in petrographic studies of ultramafic intrusions. The Canad. Mineralogist7, 403–412.Google Scholar
- McDonald, J. D., 1967: Evolution of part of the Lower Critical Zone, Farm Ruighoek, western Bushveld. J. Petrol.8, 165–209.Google Scholar
- Malpas, J., Strong, D. F., 1975: A comparison of chrome-spinels in ophiolites and mantle diapirs of Newfoundland. Geochim. Cosmochim. Acta39, 1045–1060.Google Scholar
- Menzies, M. 1975: Spinel compositional variation in the crustal and mantle lithologies of the Othris Ophiolite. Contr. Min. Petrol.51, 303–309.Google Scholar
- Muan, A., 1957: Phase equilibrium relationships at liquidus temperatures in the system FeO−Fe2O3−Al2O3−SiO2. J. Amer. Ceram. Soc.40, 420–431.Google Scholar
- , 1956: Phase equilibria at liquidus temperatures in the system MgO−FeO−Fe2O3−SiO2. J. Amer. Ceram. Soc.39, 121–141.Google Scholar
- Onyeagocha, A. C., 1974: Alteration of chromite from the Twin, Sister dunite, Washington. Amer. Min.59, 608–612.Google Scholar
- Panagos, A., 1967: Beitrag zur Kenntnis der griechischen Chromite. Ann. Géol. d. Pays Hellen.18, 1–42.Google Scholar
- Paulitsch, P., 1953 Olivinkornregelung und Genese des chromitführenden Dunites von Angitsa auf der Chalkidiki. Tschermaks Min. Petr. Mitt.3, 158–166.Google Scholar
- Peters, T. J., Kramers, J. D., 1974: Chromite deposits in the ophiolite complex of northern Oman. Min. Deposita9, 253–259.Google Scholar
- Rao, A. T., 1978: Magnetic chromites from Kondapalli, Andhra Pradesh, India. Min. Mag.42, M38–39.Google Scholar
- Sigurdsson, H., Schilling, J.-G., 1976: Spinels in mid-Atlantic ridge basalts: Chemistry and occurrence. Earth Planet. Sci. Let.29, 7–20.Google Scholar
- Stevens, R. E., 1944: Composition of some chromites of the western hemisphere. Amer. Min.29, 1–34.Google Scholar
- Stoll, W. C., 1958: Geology and petrology of the Masinloc chromite Deposit, Zambales, Luzon, Philippine Islands. Geol. Soc. Amer. Bull.69, 419–448.Google Scholar
- Thayer, T. P., 1946: Preliminary chemical correlation of chromite with the containing rocks. Econ. Geol.41, 202–217.Google Scholar
- Thayer, T. P., 1956: Mineralogy and geology of chromium. In: Chromium (Udy, M. J., ed.). Amer. Chem. Soc. Mon.132, 14.Google Scholar
- Thayer, T. P., 1960: Some critical differences between alpine-type and stratiform peridotite-gabbro complexes. Int. Geol. Congr. Rept. 21 Sess. Norden pt. 13, pp. 247–259.Google Scholar
- , 1964: Principle features and origin of podiform chromite-deposits, and some observations on the Guleman-Soridag district, Turkey. Econ. Geol.59, 1497–1524.Google Scholar
- Thayer, T. P., 1969: Gravity differentiation and magmatic reemplacement of podiform chromite deposits. In: Magmatic Ore Deposits (Wilson, H. D. B., ed.). Econ. Geol. Mon.4, 132–146.Google Scholar
- , 1970: Chromite segregations as petrogenetic indicators. Geol. Soc. S. Africa, Special Publ.1, 380–390.Google Scholar
- Van der Walt, C. J., 1941: Chrome ores of the western Bushveld Complex. Geol. Soc. S. Africa Trans.44, 79–112.Google Scholar
- Weiser, Th., 1967: Untersuchungen mit der Elektronenmikrosonde über die Zusammensetzung von Chromiten. N. Jb. Min. Abh.107, 113–143.Google Scholar
- Worst, B. G., 1960: The Great Dyke of Southern Rhodesia. Geol. Surv. Bull. S. Rhodesia47, 234.Google Scholar
- Worst, B. G., 1964: Chromite in the great dyke of Southern Rhodesia. In: The Geology of Some Ore Deposits in South Africa (Haughton, S. H., ed.), Vol. II, pp. 209–224.Google Scholar