Late Carboniferous bimodal volcanic rocks and coeval A-type granite in the Suman Khad area, Southwest Mongolia: Implications for the tectonic evolution

•There is a Late Carboniferous bimodal suite associated with coeval granites in the Suman Khad area.•The basalts were derived from partial melting of a depleted mantle source affected by the subduction-related processes.•The rhyolites stem from partial melting of juvenile basaltic crustal rocks.•Coeval granites have A-type granite affinities.•The Suman Khad bimodal suite and coeval granites formed in a back-arc extension stage of the Paleo-Asian Ocean.