Hostname: page-component-848d4c4894-tn8tq Total loading time: 0 Render date: 2024-06-16T06:37:49.524Z Has data issue: false hasContentIssue false
  • English
  • Français

The ultrabasic lava flows of Mashhad, North East Iran

Published online by Cambridge University Press:  01 May 2009

B. Majidi
B. Majidi
Affiliation:
Geological Survey of Iran, P. O. Box 1964, Tehran, Iran
Get access Rights & Permissions [Opens in a new window]

Summary

Ultrabasic and basic lavas are interbedded with metamorphosed Lower-Carboniferous sediments in the northern slope of the Alborz mountains, NE Iran. In the outcrop area at least 15 individual units of ultrabasic lava have been observed. Flow units range in thickness from a few metres up to about 70 m. The inner parts of the flow units are holo-crystalline, showing a poikilitic texture with rounded small crystals of serpentinized olivine surrounded by large crystals of clinopyroxene (‘wehrlitic facies’). The upper portions of the thicker units are olivine-free, and pyroxene, sometimes accompanied by brown hornblende, is set in a groundmass of fine-grained epidotized plagioclase (‘doleritic facies’). In the upper and lower margins of flows the groundmass is devitrified to chlorite and tremolite. Small-scale differentiation and igneous lamination is observable in transition zones between the wehrlitic and doleritic ‘facies’. The upper doleritic facies and other individual basic units have a tholeitic chemistry. In contrast, the chemical composition of wehrlitic rocks (which predominate amongst the exposed rocks in the area) is comparable with Archaean ultrabasic lava flows in Canada and southern Africa.

Type
Articles
Information
Geological Magazine , Volume 118 , Issue 1 , January 1981 , pp. 49 - 58
Copyright
Copyright © Cambridge University Press 1981

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

Arndt, N. T. & Brooks, C. K. 1980. Komatiites. Geology 8 155–6.2.0.CO;2>CrossRefGoogle Scholar
Arndt, N. T., Naldrett, A. J. & Pyke, D. R. 1977. Komatiitic and iron-rich tholeiitic lavas of Munro Township, Northeast Ontario. J. Petrology 18 319–69.Google Scholar
Bailey, E. B. & McCallien, W. J. 1953. Serpentine lavas, the Ankara melange and the Anatolian thrust. Trans. R. Soc. Edinburgh 62, II, 403–42.CrossRefGoogle Scholar
Bickle, M. J., Martin, A. & Nisbet, E. Q. 1975. Basaltic and peridotitic komatiites and stromatolites above a basal unconformity in the Belingwe greenstone Belt, Rhodesia. Earth Planet Sci. Lett. 27 155–62.CrossRefGoogle Scholar
Boulin, J. & Bouyx, E. 1977. Introduction à la géologie de l'Hindou-Kouch occidental. Mém. h. Sér. Soc. Géol. Fr. 8 87–105.Google Scholar
Brunn, J. H. 1959. La dorsale médio-atlantique et les épanchements ophiolitiques. C. r. somm. Soc. Géol. Fr. 8, 234.Google Scholar
Brunn, J. H. 1960. Mise en place et différentiation pluto-volcanique du cortège ophiolitique. Rev. Géogr. phys. Géol. dyn., vol. 3, fasc. 3, 115–32.Google Scholar
Brunn, J. H. 1973. Contribution à la discussion sur la mis en place magmatique ou tectonique des ophiolites. Note présentée au symposium sur les problèmes des ophiolites, Moscow, Mai-Juin 1973.Google Scholar
Carmichael, I. S. E., Turner, F. J. & Verhoogen, J. 1974. Igneous petrology. New York: McGraw-Hill.Google Scholar
Gass, I. G. 1958. Ultrabasic pillow lavas from Cyprus. Geol. Mag. 95 241–51.CrossRefGoogle Scholar
Irvine, T. N. & Baragar, W. R. A. 1971. A guide to the chemical classification of the common volcanic rocks. Canad. J. Earth Sci. 8 523–48.CrossRefGoogle Scholar
Macgregor, A. M. 1928. The geology of the country around the Lonely Mine, Bubi District. Bull. geol. Surv. Sth. Rhod. 11.Google Scholar
Makarychev, G. I. & Shtreys, N. A. 1973. Tectonic position of ophiolites of the southern Tian Shan. Dokl. Acad. Sci. U.S.S.R., Earth Sc. Sec., U.S.A. 210 92–3.Google Scholar
Miyashiro, A. 1975. Classification, characteristics and origin of ophiolites. J. geol. 83 249–81.CrossRefGoogle Scholar
Nisbet, E. G., Bickle, M. J. & Martin, A. 1977. The mafic and ultramafic lavas of the Belingwe Greenstone Belt, Rhodesia. J. Petrology 18, part 4, 521–66.Google Scholar
Peck, D. L., Hamilton, M. S. & Shaw, H. R. 1977. Numerical analysis of lava lake coolings models: part II application to Alae lava lake, Hawaii. Am. J. Sci. 227, April 1977, 415–37.CrossRefGoogle Scholar
Pyke, D. R., Naldrett, A. J. & Eckstrand, O. R. 1973. Archaean ultramafic flows in Munroe Township, Ontario. Bull. geol. Soc. Am. 84 955–78.2.0.CO;2>CrossRefGoogle Scholar
Searle, D. L. & Vokes, F. M. 1969. Layered ultrabasic lavas from Cyprus. Geol. Mag. 106 515–30.Google Scholar
Stocklin, J. 1974. Possible ancient continental margins in Iran. Geology of continental margins (ed. Burk, C. A. and Darke, C. L.) pp. 873–87. New York: Springer-Verlag.Google Scholar
Stocklin, J. 1977. Structural correlation of alpine ranges between Iran and central Asia. Mém. h. Sér. Soc. Géol. Fr. 8 333–53.Google Scholar
Viljoen, M. J. & Viljoen, R. P. 1969(a). Evidence for the existence of a mobile extrusive peridotitic magma from the Komati Formation of Onverwacht Group. Spec. Publ. Geol. Soc. S. Africa 2 87–112.Google Scholar
Viljoen, M. J. & Viljoen, R. P. 1969(b). The geology and geochemistry of the Lower Ultramafic Unit of the Onverwacht Group and a proposed new class of igneous rock. Spec. Publ. Geol. Soc. S. Africa 2 55–86.Google Scholar
Villaume, J. F. & Rose, A. W. 1977. The geochemistry of some Archaean ultramafic lavas. Chem. Geol. 19 43–60.Google Scholar
Wright, T. L. & Okamura, R. T. 1977. Cooling and crystallization of tholeiitic basalt, 1965 Makapuhi lava, Hawaii. Prof. Pap. U.S. geol. Surv. 1004.Google Scholar
Wyllie, J. P. 1967. Ultramafic and related rocks. New York: Wiley.Google Scholar
Wyllie, P. J. & Drever, H. I. 1963. The petrology of picritic rocks in minor intrusion, a picrite sill on the Island of Soay (Hebrides). Trans. R. Soc. Edinb. 65 155–77.CrossRefGoogle Scholar