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黑龙江省依兰地区出露了一套经高压变质形成的蓝片岩、云母片岩、长英质糜棱岩和少量超基性岩及大理岩并经历了强变形作用改造,一直被认为是佳木斯地块与其西侧松嫩地块碰撞拼贴所形成的缝合带产物。本次研究,通过岩相学与矿物化学分析,根据矿物组合的不同,识别出研究区内三种不同类型的蓝片岩;并获得了绿帘蓝闪石片岩(T=350~550℃,P=10~14kbar)、蓝闪霓辉石片岩(T=350~550℃,P=10~14kbar)和石榴石冻蓝闪石片岩(T=500~540℃,P=10~12kbar)的峰期变质温压条件。结合前人发表的地质年代学数据,建立了变质演化P-T-t轨迹。其中,绿帘蓝闪石片岩具“发卡式”变质演化P-T-t轨迹;而蓝闪霓辉石片岩与石榴石冻蓝闪石片岩具顺时针的演化轨迹。我们推测其成因可能为不同类型的蓝片岩形成于不同的俯冲阶段,由动力学机制的变化所造成。该研究成果为进一步探索佳木斯地块与松嫩地块碰撞拼贴的构造演化过程提供重要的依据。
Heilongjiang Yilan area exposed a set of high-pressure metamorphism formed blue schist, mica schist, felsic mylonites and a small amount of ultrabasic rocks and marble and experienced strong deformation transformation, has been considered Jiamusi Block and its west Songnei block collision collage formed by the suture product. In this study, three different types of blue schist were identified in the study area by petrography and mineral chemical analysis based on the different mineral assemblages. The results showed that the kapokite dolomite (T = 350-550 ℃, P = 10 ~ 14kbar), peak of glaucite-titanitic schist (T = 350-550 ℃, P = 10 ~ 14kbar) and garnet-glaucophane schist (T = 500-540 ℃, P = 10-12kbar) Period of metamorphic temperature and pressure conditions. Combined with the published geochronology data, the metamorphic evolution P-T-t trajectory was established. Among them, the chlorite dolomite with “hairpin” metamorphic evolution P-T-t trajectory; while the blue flash anonite schist and garnet frozen blue dolomite with a clockwise evolution trajectory. We speculate that its origin may be due to the different types of blue rocks formed in different subduction stages, caused by the change of dynamic mechanism. The research results provide an important basis for further exploration of the tectonic evolution of collision and collage between Jiamusi Block and Songnen Block.