The spatial and compositional evolution of the Late Jurassic Ghorveh-Dehgolan plutons of the Zagros Orogen, IranSHRIMP zircon U-Pb and Sr and Nd isotope evidence
- S. Yajam 1
- P. Montero 2
- J. H. Scarrow 2
- J. Ghalamghash 3
- S. M. H. Razavi 1
- F. Bea 2
- 1 Kharazmi University (Teheran, Iran). Department of Geology
- 2 Universidad de Granada. Departamento de Mineralogía y Petrología
- 3 Research Institute for Earth Sciences (Teheran, Iran). Geological Survey of Iran
ISSN: 1695-6133
Año de publicación: 2015
Volumen: 13
Número: 1
Páginas: 25-43
Tipo: Artículo
Otras publicaciones en: Geologica acta: an international earth science journal
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.