The Baiganhu area is a new large W–Sn belt in northwest China.
Tourmalines are related to the Li-poor granites and the Al-saturated metapelites.
The cores are depleted in Mg, Ca, Ti, and enriched in Al and Fe relative to the rims.
B-isotope ratios of tourmalines range from − 12.9 to − 7.9‰ δ11B.
B-isotope reflects a single granite-derived magmatic-hydrothermal origin.