吉林通化地区元古代岩石地层研究

Study of Paleoproterozoic strata in Tonghua area of Jilin Province

以宏观岩石学为基础,结合侵入岩事件、高精度同位素测年、变质变形特征、岩石化学及地球化学特征,对通化地区古元古代、中元古代"岩石地层"单位重新进行划分和厘定,并赋予新的含义。研究结果表明:通化地区出露的古元古代、中元古代岩石地层自下而上划分为光华岩群、集安岩群和老岭群,光华岩群与集安岩群呈整合接触关系,为同一时期、同一地球动力学机制下裂谷构造环境的产物,老岭群角度不整合覆盖于集安岩群之上。LA-ICPMS锆石U-Pb同位素测年显示,光华岩群双庙岩组变质玄武岩形成年龄为(2 120±10)Ma。

Based on macroscopic petrography, in combination with intrusive rocks events, high-precision isotopic dating, metamorphism and deformation characteristics, petrochemistry and geochemistry, the authors re-divided the Paleoproterpzoic and Mesoproterozoic lithostratigraphic units, and give them new meanings. The results show that the Paleoproterozoic and Mesoproterozoic strata outcropped from the bottom to the upper in Tonghua area are Guanghua Group Complex, Ji＇an Group Complex and Laoling Group. Guanghua Group Complex appeared conformable contact with Ji＇an Group, which formed in the same period and environment under the same geodynamic mechanism. Laoling Group unconformably overlay on Ji＇an Group. By using the method of high-precision zircon LA-ICPMS isotopic dating, it is determined that the forming age of the metamorphic basalt from Shuangmiao Formation in Guanghua Group Complex is 2 120±10 Ma.