Source and evolution of the ore-forming fluid of the Cuonadong Sn-W-Be polymetallic deposit (southern Tibet, China): Constraints from scheelite trace element and Sr isotope geochemistry

•Skarn-type mineralization of the Cuonadong Sn-W-Be polymetallic deposit occurred at ca. 15 Ma.•Skarn-hosted scheelite can be divided into an older type 1 scheelite and a younger type 2 scheelite.•The ore-forming fluid was exsolved from the Cuonadong Miocene leucogranite.•Geochemically and isotopically, the ore-forming fluid was modified by intense fluid-rock interaction during skarnization and greisenization.