High magmatic flux during Alpine-Himalyan collision: constraints from the Kal-e-Kafi complex, central Iran

Ahmandian, Jamshid, Haschke, Michael, McDonald, Iain ORCID: https://orcid.org/0000-0001-9066-7244, Regelous, Marcel, RezaGhorbani, Mohammed, Hashem-Emami, Mohammed and Murata, Mamoru 2009. High magmatic flux during Alpine-Himalyan collision: constraints from the Kal-e-Kafi complex, central Iran. Geological Society of America Bulletin 121 (5-6) , pp. 467-480. 10.1130/B26279.1

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Abstract

Voluminous Eocene gabbros to granites of the Kal-e-Kafi backarc composite intrusion were emplaced prior to the Alpine-Himalayan collision in the central Iranian backarc, but the reasons for precollisional high arc and backarc magmatic productivity (60–53 Ma) are unclear. Diagnostic geochemical signatures are high K2O-Sr contents and successively depleted middle rare earth element (REE) patterns, reflecting a highly metasomatized source and an increasing role for amphibole and garnet (0%–10%) in the relatively younger granites. Release of concealed K-Sr-rich fluids from oceanic fractures and faults during buckling and bulging of a precollisional choking oceanic slab, and melting of phlogopite-bearing lithosphere with subsequent interaction of the melt with lower crustal garnet-amphibolite of a ~40-km-thick crust, can explain the Kal-e-Kafi geochemical and isotopic signatures. Gravimetric data indicating a ~39 km present-day backarc crustal thickness are consistent with geochemical results but also imply little if any collisional crustal thickening of the central Iranian Plateau. High Eocene arc-backarc melt flux prior to collision in this region reflects vigorous thermal convection, which may in fact be diagnostic of collisional magmatism, explaining the presence of postcollisional shoshonitic melts in this and other collisional orogenic settings.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Earth and Environmental Sciences
Subjects:	Q Science > QE Geology
Uncontrolled Keywords:	backarc magmatism ; Central Iran ; Alpine-Himalayan collision ; Amphibole ; Crustal thickening
Publisher:	Geological Society of America
ISSN:	0016-7606
Last Modified:	18 Oct 2022 12:23
URI:	https://orca.cardiff.ac.uk/id/eprint/9657

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