Abstract:

The Ganbahenao deposit in the north Qilian Mountains is a middle Mo[CD*2]W deposit newly discovered in the western segment of north Qilian Mountains.It belongs to the quartz vein type.Both molybdenite and wolframite are dominant metal minerals in the ore. Through the study of the geological features of the deposit， the C，H， O  isotopic compositions of fluid inclusions in quartz and the content of both Re and S in molybdenite， authors conclude that ore-forming materials were derived from the crust， the ore-forming fluid mainly came from the magmatic fluid. The Ganbahenao deposit was genetically related to the S-type granite. Re-Os dating of molybdenite yields model ages between (413.3±6.0)-(426.4±6.6) Ma and an isochrone age of (424±10) Ma， which is nearly equal to  that of the wall rock， the Jinfosi Stype plutons.The Ganbahenao deposit and the Jinfosi plutons are formed in the environment of the continent-continent collision after the closure of the north Paleo-Qilian ocean in Late Silurian Period.The Jinfosi plutons offers the ore-forming sources and space.

Key words: Ganbahenao, Mo-W deposit, stable isotope, Re-Os isochron age, Jinfosi granite, molybdenite