Sm-Nd isotopic compositions of deep-marine mudstones, Xigaze forearc basin, southern Tibet: Implications for drainage evolution and expansion

•The mudstones were sourced from a mixture of the Gangdese arc and Lhasa terrane.•The contribution of central to northern Lhasa terrane sources increases upsection.•Drainage expansion accounts for the variation of Nd signatures in megasequences.