Document Type : Original Research Paper


1 Department of Geology, Payame Noor University (PNU), Iran

2 Department of Earth Sciences, University of Milano, Milano, Italy


The Malayer-Boroujerd plutonic complex (MBPC) is part of the Sanandaj-Sirjan continental arc of Iran resulted from subduction of Neotethys oceanic crust below Central Iran microcontinent. A number of adakitic samples have recently been reported in the MBPC. This study shows that among the various petrogenetic processes responsible for the formation of adakitic rocks, two have been suggested in the genesis of those from the MBPC. i) interaction of crust-derived magma with ultramafic rocks and ii) crystallization of amphibole from a more basic magma. The former process leads to formation of intermediate to basic magma that subsequently crystallized amphibole in the ultramafic rocks. Amphibole growth was associated with textural and chemical changes toward the rim. Chemical modeling shows that amphibole growth was coeval with assimilation of olivines that their residue are remained as inclusions in the amphibole. The magma that formed the rim of amphiboles had higher Th, Zr, Ta and LREE but lower Ti and HREE than the core-forming magma. Assimilation of olivine during the amphibole growth prevented a decrease in Ni and Co content of the remained magma. Comparable chemistry of the rim-forming melt and MBPC adakitic rocks suggest that they are of the same origin. 


Main Subjects

Ahmadi Khalaji, A.A., Esmaeily, D., Valizadeh, M.V., and Rahimpour-Bonab, H., 2007. Petrology and geochemistry of the granitoid complex of Boroujerd, Sanandaj-Sirjan Zone, Western Iran, Journal of Asian Earth Sciences, 29, 859- 877.
Atherton, M.P., and Petford, N., 1993. Generation of sodium-rich magmas from newly underplated basaltic crust, Nature,  362, 144 -146. 
Berberian, F., and Berberian, M., 1981. Tectono-plutonic episodes in Iran. In: Gupta, H.K., Delany, F.M. (eds) Zagros–Hindu Kush–Himalaya Geodynamic Evolution. American Geophysical Union, Geodynamics Series, 3, pp. 5–32.
Castillo, P.R., 2006. An overview of adakite petrogenesis, Chinese Science Bulletin, 51(3), 257–268.
Castillo, P.R., 2012. Adakite petrogenesis, Lithos, 134- 135, 304- 316.
Davidson, J., Turner, S., Handley, H., Macpherson, C., and Dosseto, A., 2007. Amphibole ‘sponge’ in arc crust?, Geology, 35, 787-790.
Deevsalar, R., Shinjo, R., Ghaderi, M., Murata, M., Hoskin, P.W.O., Oshiro, S., Wang, K.L., Lee, H.Y., and Neill, I., 2017. Mesozoic- Cenozoic mafic magmatism in Sanandaj-Sirjan Zone, Zagros Orogen (Western Iran): Geochemical and isotopic inferences from Middle Jurassic and Late Eocene gabbros, Lithos, 
284- 285 ,588-607.
Defant, M.J., and Drummond, M.S., 1990. Derivation of some modern arc magmas by melting of young subducted lithosphere, Nature, 347, 662―665. 
Dorais, M., and Tubrett, M., 2008. Identification of a subduction zone component in the Higganum dike, Central Atlantic Magmatic Province: A LA-ICPMS study of clinopyroxene with implications for flood basalt petrogenesis, Geochemistry Geophysics Geosystems, 9, 1-13.
Esna-Ashari, A., and Tiepolo, M., 2020. Petrogenesis of gabbroic rocks from the Malayer plutonic complex (Sanandaj-Sirjan zone, west Iran), Periodico di Mineralogia, 89, 91- 104.
Esna-Ashari, A., and Tiepolo, M., 2021. Reply to Deevsalar and Shinjo (2020) comments on “Petrogenesis of gabbroic rocks from the Malayer plutonic complex, Sanandaj-Sirjan zone, west Iran” (Esna-Ashari and Tiepolo, Periodico di Mineralogia 89, 91-104, 2020), Periodico di Mineralogia, 90, 211- 215. 
Esna-Ashari, A., Tiepolo, M., Valizadeh, M.V., Hassanzadeh, J., and Sepahi, A.A., 2012. Geochemistry and zircon U-Pb geochronology of Aligoodarz granitoid complex, Sanandaj-Sirjan Zone, Iran, Journal of Asian Earth Sciences, 43, 11- 22.
Esna-Ashari, A., Tiepolo, M., and Hassanzadeh, J., 2016. On the occurrence and implications of Jurassic primary continental boninite-like melts in the Zagros orogen, Lithos, 258- 259, 37- 57. 
Kelemen, P.B., 1995. Genesis of high Mg-number andesites and the continental crust, Contributions to Mineralogy and Petrology, 120, 1- 19.
Kelemen, P.B., Joyce, D.B., Webster, J.D., and Holloway, J.R., 1990. Reaction between ultramafic rock and fractionating basaltic magma. Experimental investigation of reaction between olivine tholeiite and harzburgite at 1150-10508C and 5 kb, Journal of Petrology, 31, 99-134.
Qian, Q., and Hermann, J., 2010. Formation of high-Mg diorites through assimilation of peridotite by monzodiorite magma at crustal depths, Journal of Petrology, 51, 1381- 1416.
Qu, X.-M., Hou, Z. Q., and Li, Y. G., 2004. Melt components derived from a subducted slab in late orogenic ore-bearing porphyries in the Gangdese copper belt, southern Tibetan plateau, Lithos, 74, 131- 148. 
Rollinson, H., and Martin, H., 2005. Geodynamic controls on adakite, TTG and sanukitoid genesis: implications for models of crust formation, introduction to the special issue, Lithos, 79, ix–xii.
Tiepolo, M., Oberti, R., Zanetti, A., Vannucci, R., and Foley, S.F., 2007. Trace-element partitioning between amphibole and silicate melt, Reviews in Mineralogy and Geochemistry, 67, 417- 452.
Tiepolo, M., Tribuzio, R., and Langone, A., 2011. High-Mg Andesite Petrogenesis by Amphibole Crystallization and Ultramafic Crust Assimilation: Evidence from Adamello Hornblendites (Central Alps, Italy), Journal of Petrology, 52, 1011- 1045.
Wang, Q., McDermott, F., Xu, J.F., Bellon, H., and Zhu, Y.T., 2005. Cenozoic K-rich adakitic volcanic rocks in the Hohxil area, northern Tibet: lower-crustal melting in an intracontinental setting, Geology, 33, 465–468.
Yogodzinski, G.M., and Kelemen, P.B., 1998. Slab melting in the Aleutians: Implication of an ion probe study of clinopyroxene in primitive adakite and basalt, Earth and Planetary Science Letters, 158, 53- 65. 
Yumul, Jr. G.P., Dimalanta, C.B., Faustino, D.V., and De Jesus, J.V., 1999. Silicic arc volcanism and lower crust melting: an example from the central Luzon, Philippines, Journal of Geology, 154, 13- 14. 
Zhang, Z., Xiao, W., Ji, W., Majidifard, M.R., Rezaeian, M., Talebian, M., Xiang, D., Chen, L., Wan, B., Ao, S., and Esmaeili, R., 2018. Geochemistry, zircon U-Pb and Hf isotope for granitoids, NW Sanandaj- Sirjan zone, Iran: Implications for Mesozoic-Cenozoic episodic magmatism during Neo-Tethyan lithospheric subduction, Gondwana Research, 62, 227- 245.