Origin and Geodynamic Mechanism of the Tibetan Demingding Porphyry Mo (Cu) Deposit from Oceanic Subduction to Continental Collision

Demingding is a promising porphyry Mo-dominated deposit recently discovered in the eastern Gangdese metallogenic belt Tibet, China. We present zircon U-Pb-Lu-Hf isotopic studies, as well geochemical data of late monzogranites and prior rhyolites from to uncover their origin geodynamic mechanism. Zircon U–Pb dating yielded precise crystallization ages 17.3 ± 0.6 Ma (MSWD = 2.5) 186.5 3.0 2.0) for monzogranite rhyolite, respectively. The characterized by high-K calc-alkaline, adakitic affinities, positive εHf(t) values (+0.9∼+5.6, avg.+3.1) with TDM2 (0.73–1.04 Ga), while rhyolite has (+2.1∼+7.3, avg.+5.2) (0.76–1.09 Ga) similar monzogranite. Our results suggest that Mo (Cu) related magma generated Neo-Tethyan oceanic subduction. subsequent was likely formed remelting previously subduction-modified arc lithosphere, triggered continental collision crustal thickening Miocene. lower minor inputs Mo-rich ancient crust, suggesting favors silicate melt. Such magmatic events special metallogenesis typify intracontinental processes copper deposits, which are normally confined subduction Cu-dominated style, thereby making setting style exceptional possibly unique.