The Devonian marine spilite-keratophyre association in the Ashele copper deposit, Xinjiang, bears typical characteristics of bimodal volcanic rocks, because basic and acid volcanic rocks may be often found to alternate closely with each other on the surface and in cores of drill holes and intermediate rocks with 54%-61% SiO2 are lacking, especially in the Early-Middle Devonian Ashele Formation which hosts bedded copper orebodies. Rare earth element and minor element geochemistry of bimodal volcanic rocks indicate that the basic and acid volcanic rocks originated from different sources rather than a common magma chamber. The lead isotopic composition of ores is consistent with that of spilite, and sulfur isotopes show a distribution of tower type, illustrating that both ore-forming and rock-forming materials were derived from depths. So the Ashele Cu-Zn polymetallic ore deposit is of a volcanic-type massive sulfide deposit, controlled by continental-margin marine bimodal volcanism occurring in an extensional setting in the Devonian.