Abstract: Mafic dikes,which widely developed in Kukexiluke region,Xinjiang,mainly present as dikes,apophysis and small bosses.The types of the mafic dikes are gabbros and diabases.The gabbros belong to the alkalic series basalt, while the diabases belong to a type transitional from peraluminous alkalic basalt to trachybasalt;the forming depth of diabases(shallow phase) is more shallow than that of gabbros(mid-plutonic phase).The mafic dikes in the region mainly formed in an environment of closed marginal island arc and active continental marginal orogenic belt,the original mantle-derived magma experienced assimilation and contamination of the crustal materials during its differentiation,the crystallization differentiation was the main factor to control the evolution of the magma.The gabbros are characterized by slight δEu depletion.While the mixed crust-mantle-derived diabases show positive δEu anomaly,weak Ce depletion and distinctive high oxygen fugacity,suggesting its genesis similar to that of I-type granites.The gabbros originated from a mantle-dominated source,while diabases originated from a crust-dominated source contaminated by surrounding rocks during ascending of the mantle-derived magma.The age of gabbros(119 Ma) is more old than that of diabases(46.1 Ma),which implies that the gabbros represent the termination of thrusting compression during the collision of Gangdese craton with Northern Eurasia plate.The diabases represent the termination of the large-scale thrust-related compression and shearing and are the result of initial extension of Tibetan plateau.