Mineralogy, isotope geochemistry and ore genesis of the Miocene Cuonadong leucogranite-related Be-W-Sn skarn deposit in Southern Tibet

•The Cuonadong Be-W-Sn skarn deposit in Tibet is newly discovered and belongs to a new type of deposits for exploration.•The hosting rocks were emplaced at 18 Ma and contains older xenolithic zircon grains with ages of 490 Ma and 711 Ma.•Strong water-rock interaction was favorable for the formation of scheelite.•Highly differentiated nature of magmas was necessary for the enrichment of Be and REEs.