摘要
内蒙集宁三岔口地区早前寒武纪经历两期麻粒岩相交质作用。第一期变质作用发生于2.5Ga,变质作用峰期温度为770～850℃,压力为0.85～1.0GPa,属于迅速增温增压到降温降压的P-T-t演化轨迹,这和本区变质岩系发生构造加厚作用有关.第二期变质作用发生于2.0Ga,变质作用峰期温度为800士20℃,压力为0.53～0.68GPa,其P-T-t轨迹属于典型的造山带型演化模式。
Two epoches of granulite-facies metamorphism are recognized in Sanchakou, Jining, InnerMongolia. The first epoch of metamorphism , occuring around 2500Ma. reached its peak condition of T=720-850℃ and P=0. 84- 1. 05GPa. It belongs to a pattern of quickly raising P-T, then declining. This process may be genetically related to tectonic thickness of supercrustal pile of this area. The second metamorphic event took place at about 2000Ma. Its peak P-T condition is 800±20℃ and 0. 53-0. 68GPa. The P-T-t path in the second stage of metamorphism is a kind of evolution pattern which typically belong to erogenic belt.
关键词
早前寒武纪
变质作用
麻粒岩相
Early Precambrian period , metamorphism, qranulite-facies, P-T-t path, Jining
