Long-lived magmatic evolution and mineralization resulted in formation of the giant Cuonadong Sn-W-Be polymetallic deposit, southern Tibet

•The Cuonadong leucogranites are peraluminous S-type granites and were derived from metapelites of the Higher Himalayan Crystalline Sequence.•Intense fractional crystallization occurred during magma evolution, which leaded to remarkable enrichment of Be, Sn and W in the residual magma.•The long-lasting (21–15 Ma) fractional crystallization and rare-metal mineralization (18–14 Ma) collectively resulted in the supernormal enrichment of Sn, W, and Be in the Cuonadong Sn-W-Be polymetallic deposit.