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GE0CHRONOL0GlCAL STUDIES 0F RAPAKIVI GRANITES IN OINLING AND ITS GEOLOGICAL IMPLICATIONS

Lu Xin-xing1;2, Wei Xiang-dong1, Xiao Qing-hui3, Zhang Zhong-qing4, Li Hui-min3, Wang Wei1   

  1. 1. Geological Research Institute of Henan Province, Zhengzhou, 450053; 2. State Key Laboratory for Mineral Deposits Research, Nanjing University, Nanjing, 210093; 3. Chinese Institute of Geology and Mineral Resources Information, Beijing, 100037; 4. Institute of Geology, Chinese Academy of Geological Science, Beijing, l00037; 5. Tianjin Institute of Geology and Mineral Resources, Tianjin, 300170
  • Received:1999-12-20 Revised:1999-12-20 Online:1999-12-20 Published:1999-12-20

Abstract: The Qinling orogenic belt is a famous continental orogenic belt in the world with signature of multistage and multi-system evolution. It underwent all geological evolutionary processes including preorogenic, climacticorogenic and postorogenic phases. But until now, there is still different understanding in the terminal stage of the climactic orogenic phase. Discovery of rapakivi granites distributed in the main suture zone of Qinling orogenic belt (Shangdan tectonic zone) has provided a possibility to solve this important geological problem. It is an indisputable fact that rapakivi granites are regarded as the result of post-orogenic magmatism. Therefore, the terminal time of the climactic orogenic phase of Qinling belt can be estimated by accurate dating of formation age of the Qinling raprkivi granites. Based on the systematic dating of rapakivi granite belt and analysis of U-Pb, Rb-Sr, Ar-Ar and K-Ar age data in Qinling, we regard 210-217Ma as the terminal time of the Qinling climactic orogenic phase. This precise evidence has an important scientific significance in understanding the geological history of th eQinling orogenic belt.