The Late Yanshanian extensional environment gave rise to detachments,including peel thrusts, at various tectonic levels on both sides of the deep faultbelt or rift belt. F_(15) peel thrust (system) at the southern side of the Xinjiangrift belt is a dominant ore-controlling factor of deposit No. 50. It is beleived tocontroll the source of ore substances and their precipitation and siting of theorebodies. Besides, the paper also discusses the significance of peel thrusts inmineral prospecting.