The spatial and compositional evolution of the Late Jurassic Ghorveh-Dehgolan plutons of the Zagros Orogen, Iran: SHRIMP zircon U-Pb and Sr and Nd isotope evidence
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S. Yajam [2] ; P. Montero [1] ; J. H. Scarrow [1] ; J. Ghalamghash [3] ; S. M. H. Razavi [2] ; F. Bea [1]
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[1] Universidad de Granada
Universidad de Granada
Granada, España
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[2] Kharazmi University (Teheran, Iran). Department of Geology
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[3] Research Institute for Earth Sciences (Teheran, Iran). Geological Survey of Iran
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- Localización: Geologica acta: an international earth science journal, ISSN 1695-6133, Vol. 13, Nº. 1, 2015, págs. 25-43
- Idioma: inglés
- Enlaces
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Resumen
The Ghorveh-Dehgolan plutons of the northern Sanandaj-Sirjan Zone, Zagros Orogen, comprise seven composite intrusive bodies that were generated during northeastward subduction of Neotethys beneath the Iranian sector of the Eurasian plate. Zircon U-Pb SHRIMP dating reveals that the magmatic activity spanned from ~160 to ~140Ma. It started with intrusion of arc-related calc-alkaline mafic to intermediate rocks closely followed by felsic I-type granitoids. This magmatism was post-dated by felsic alkaline A-type granites. In addition to compositional changes over time, the plutons forming the arc young towards the southwest: the north Ghorveh batholith (161±4Ma) and Shanevareh (160±2Ma); Qalaylan (159±3Ma); then central Ghorveh, Galali and Saranjianeh (151±0.2Ma to 148±1Ma); and, lastly, the south Ghorveh batholith (147±3Ma) and Bolbanabad-Havarpan (144±1Ma). Whatever the process driving the changes, be it arc- or ridge-collision with the subducting system, slab roll-back, slab breakoff, subduction initiation transference, etc., the progression from I-type to A-type magmatism appears to mark a significant change from a collisional to an extensional setting in the region in the Late Jurassic. Geochemical and isotopic characteristics of the Ghorveh-Dehgolan plutons indicate that Arabian-Nubian-like crust was an important component of the magmatic sources.
