盐边群地层特征及其大地构造属性

Study on Stratum Characteristic and Geotectonic Feature of the Yanbian Group

通过对盐边群各岩性段地层的产出、构造变形特征及相互间的接触关系的确认,在对碎屑岩组段进行颗粒骨架分析的基础上,结合已有的地球化学和同位素年代学研究结果,盐边群火山岩及其南侧的深成岩均不是蛇绿岩的组份,该火山岩可能形成于弧后伸展环境,盐边群中下碎屑岩段形成于弧后盆地,而上部碎屑岩段则可能形成于前陆盆地。研究表明,在华南板块西缘存在南北向格林威尔期的板块碰撞事件,盐边群地层可能记录了格林威尔期发生在华南地块西缘由孤后盆地到前陆盆地的整个演化历史。

Based on the field research and laboratory analysis, together with the research on the geochemistry and geochronology, the volcanic and the plutonic formations of Yanbian Group are not components of a ophiolite suite. The volcanic-sedimentary, rock that the lower part of the Yanbian Group is deposited in a back-arc basin setting, and the Zagu formation is deposited in a retroarc basin setting based on the analysis of stratigraphy, geochemistry and clastic petrofacies. The direction of the Grenville-aged deformation structures of Yanbian group is WE, which indicate that there had been a Grcnville-aged Orogenic event in the west margin of the South China Block and the stretch direction of the Orogenic belt is WE.