鲁东地区早前寒武纪花岗岩类演化及大陆地壳生长

Evolution and Continental Crust Growth of Early Precambrian Granitoids in Eastern Shandong Province

摘要:

通过对太古宙和古元古代花岗岩成分判别分析，提出了鲁东地区早前寒武纪花岗岩类可能分为3期，第一期为中太古代TTG组合，发育不完全；第二期为新太古代T1T2G1组合，具有贫K2O的奥长花岗岩演化趋势；第三期为古元古代早期G2组合，仅具富K2O的钙碱性演化趋势。探讨了不同组合花岗岩的形成环境，新太古代T1T2G1组合为岛弧环境，古元古代早期为大陆碰撞环境；不同的花岗岩类岩石组合分别对应的陆壳成熟度为：T1T2G1组合为新生的初始不成熟陆壳，G2组合则为最终的成熟陆壳。鲁东早前寒武纪花岗岩类随时间从新太古代至古元古代早期的演化，记录了鲁东大陆地壳形成的完整的地质演化过程。

Abstract:

Through analysis and discrimination of the granite compositions in Archean and Paleoproterozoic period, granitoids in early Precambrian period in eastern Shandong province can be divided into three stages. The first stage is Archean TTG combination with incomplete development; the second stage is Neoarchean T2G1T1 combinations with the trend of poor K2O trondhjemite evolution; the third stage is the early Paleoproterozoic G2 combination with rich K2O calcalkaline evolutionary trend. Forming environment of different granites combinations have been studied. The Neoarchean T1T2G1 combination is islandarc environment, while the environment of the early Paleoproterozoic is continental collision. Different combination of granitoid rocks correspond to different maturity of the continental crust: T1T2G1 combination is new initial immature continental crust, while G2 combination is a final maturity of continental crust. Evolution of the early Precambrian granitoids over time from Neoarchean to Paleoproterozoic early has recorded the geological evolution of continental crust in eastern Shandong completely.