Geochemistry and petrogenesis of gabbroids in the Soleimanieh ophiolites, Sabzevar

Abstract

The Soleimanieh ultramafic-mafic cumulate rocks (East of Sabzevar) include gabbronorites, amphibole gabbronorites, pegmatite gabbros, leucogabbronorites, norites, diorites and plagioclase bearing amphibole peridotites. The Cr-number of spinels in amphibole peridotites and olivine gabbronorites varies from 0.44 to 0.45 and 0.42 to 0.44 respectively. Geochemically, the gabbroic rocks are characterized by Mg# between 50 to 65% and their composition is directly related to modal abundances of the main rock-forming minerals. They have low TiO2 content, indicating boninitic to highly depleted island-arc tholeiitic affinities for their parental melts. The rocks have flat to depleted LREE patterns (relative to HREE). Enrichment in LILE and depletion in HFSE are characteristics of the Soleimanieh gabbroic rocks, showing formation of the rocks in a supra-subduction zone environment. Compared to the gabbroic rocks, the Sabzevar lavas have calc-alkaline characteristics and seem to be formed in a subducton zone environment.

Keywords


[1] Dilek Y., Furnes H., Shallo M., "Suprasubduction zone ophiolite formation along the periphery of Mesozoic Gondwana", Gondwana Research. 11(2007) 435-475.

[2] Kusky T.M., "Precambrian ophiolite and related rocks", Developments in Precambrian Geology 13(2004) Elsevier Publications.

[3] Santosh M., Maruyama S., Sato K., "Anatomy of a Cambrian suture in Gondwana: Pacific-type orogeny in southern lndia? ", Gondwana Research. 16 (2009) 321-341.

[4] Pearce J.A., ROBINSON P.T., "The Troodos ophiolite complex probably formed in a subduction initiation, slab edge setting", Gondwana Research. 18 (2010) 60-81.

[5] Yellappa T., Santosh M., Chetty T.R.K., Kwon S., Park C., Nagesh P., Mohanty D.P., Venkatasivappa V., "A Neoarchean dismembered ophiolite complex from southern India: Geochemical and geochronological constraints on its supra-subduction origin", Gondwana Research) 2011). doi:10.1016/j.gr. 05.300.

[6] Rocci G., Ohnenstetter D., Ohnenstetter M., "La dualite des ophiolites Tethysiennes", Petrologie. 1(1975) 172-174.

[7] Abbate E., Bortolotti V., Principi G., "Apennine ophiolites: a peculiar oceanic crust", Ofioliti. 1(1980) 59-96.

[8] Pearce J.A., "Geochemical evidence for the genesis and eruptive setting of lavas from Tethyan ophiolites", In: Panayiotou A. (Ed.), Ophiolites. Proc. Int. Ophiolite Symp., Nicosia, Geol. Surv. Dep. (1980) 261-272.

[9] Pearce J.A., Alabaster T., Shelton A.W., Searle M.P., "The Oman ophiolite as a Cretaceous arc-basin complex: evidence and implications Philos", Trans. R. Soc. London A300 (1981) 299-317.

[10] Takin M., "Iranian geology and continental drift in the Middle East", Nature 235 (1972) 147-150.

[11] Stocklin J., "Possible ancient continental margins in Iran. In: Burke, C.A., Drake, C.L. (Eds.), The Geology of Continental Margins", Springer, New York. (1974) 873-887.

[12] McCall G.J.H., "The geotectonic history of the Makran and adjacent areas of southern Iran ", Journal of Asian Earth Sciences. 15 (1977) 517-531.

[13] Shojaat B., Hassanipak A.A., Mobasher K., Ghazi A.M., "Petrology, geochemistry and tectonics of the Sabzevar ophiolite, North Central Iran", Journal of Asian Earth Sciences. 21(2003) 1053-1067.

[14] Ohnenstetter M., "The role of possible transverse faults in the development of the Sabzevar Ophiolites, North-East Iran, with special refrence to magma chamber tectonics", hese Sci.Geol., Bull., 36,1(1983)73-90, Strasbourg.

[15] Kamenetsky V. S., Crawford A. J., Meffre S., "Factors controlling of magmatic spinel: an empirical study of associated olivine, er- spinel and melt inclusion from primitive rocks", J. Petrol.42 (2001) 655-671.

[16] Nicolas A., "Structure of ophiolites and dynamics of oceanic lithosphere", kluwer Academic Pub (1989) 367 P

[17] McDonough W. F., Sun S. S., "The composition of the Earth", Chemical Geology. 120 (1995) 223-253.

[18] Sun S. S., McDonough W. F., "Chemical and isotopic systematic of oceanic basalt: implications for mantle composition and process. In Magmatism in Ocean Basins", (eds A.D. Saunders,M.J. Norry), Geological Society, Special Publication, London, (1989) 313-345.