藏北羌塘中部沿龙木错-双湖-线出露一条低温高压变质带,目前已有多处蓝片岩的报道.然而,除冈玛错地区产有典型的蓝闪石外,多数地区并没有典型蓝闪石的报道.绒玛蓝片岩位于羌塘中部高压变质带的中段,是该带中规模最大、保存最好的蓝片岩,对蓝片岩进行了详细的岩石学和矿物学研究,钠质角闪石主要为蓝闪石、青铝闪石、钠闪石和镁钠闪石.对蓝片岩中蓝闪石和多硅白云母进行了~(40)Ar/~(39)Ar定年,获得了227.3±3.8Ma和215±1.5Ma的坪年龄,分别代表蓝片岩快速俯冲消减和俯冲作用结束开始折返抬升的时代.绒玛蓝片岩岩石学、矿物学和40~(Ar)/~(39)Ar年代学研究为羌塘中部高压变质带的研究提供了新的资料.%Low temperature high pressure (LT-HP) metamorphic belt distributing along Longmucuo-Shuanghu suture is consisting of blueschist and eclogite. However, scarcely representative glaucophances are reported in the blueschists except for that from Gangmacuo. Rongma blueschist lies in the central of this LT-HP metamorphic belt, and is the largest and best preserved blueschist in central Qiangtang. Based on detailed petrology and mineralogy study, glaucophance, crossite, riebeckite and magnesian riebeckite are identified. Ar/ Ar dating for the glaucophance and phengite from the blueschist yields the plateau ages of 227 ±4Ma and 215 ±2Ma, and indicate the subduction and exhumation age of the blueschist, respectively. This study has provided new data for the research work on the LT-HP metamorphic belt in central Qiangtang, northern Tibet.
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