Paper Number: 2520
U–Pb zircon ages, field geology and geochemistry of the Kermanshah ophiolite (Iran): From continental rifting at 79 Ma to oceanic core complex at ca 36 Ma in the southern Neo-Tethys
Songjian Ao 1, Wenjiao Xiao *,1,2,3,
1 State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
2 CAS Center for Excellence in Tibetan Plateau Earth Sciences, PR China
3 Xinjiang Research Center for Mineral Resources, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China
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The geodynamic evolution of the Zagros Mountains of Iran remains obscure. In particular, the time of formation of the Zagros ophiolites and the closure of the Neo-Tethys Ocean are highly controversial. Here we present new precise zircon U–Pb ages that show that the younger part (Sahneh–Kamyaran) of the Kermanshah ophiolite formed at 35.7 ± 0.5 Ma and the older part (Harsin) at 79.3 ± 0.9 Ma. Field relations and geochemical evidence show that the younger Sahneh–Kamyaran part is probably a fossil oceanic core complex, and the older Harsin part is probably a continental-oceanic transition complex. Both the Sahneh–Kamyaran and Harsin parts were later emplaced into an accretionary complex. We conclude and infer that the final closure time of the southern Neo-Tethys Ocean was after the Late Eocene. Our data and tectonic model have crucial implications for the geodynamic evolution of the Zagros region.
Keywords: Oceanic core complex, Kermanshah ophiolite, Neo-Tethys, U-Pb age, Iran
Reference:
[1] Ao Songjian et al. (2015) Gondwana Research, http://dx.doi.org/10.1016/j.gr.2015.01.014