SHRIMP U-Pb geochronology of the zircons from the Precambrian basement of the Qilian Block and its geological significances

• DOI: 10.1007/s11434-007-0356-0
• Publication Date: 2007-10-02T10:19:03Z
• Authors: Kuoan Tung; Huai-Jen Yang; Houng-Yi Yang; DunYi Liu; JianXin Zhang; YuSheng Wan; Chien-Yuan Tseng
• Keywords: 01 natural sciences; 0105 earth and related environmental sciences

Origin and tectonic evolution of the Qilian Precambrian basement on NW China were investigated using zircon U-Pb ages with collaborating stratigraphic and paleontological evidence. Zircon grains were separated from two schists, two granitic gneisses and one mylonized gneiss and dated with SHRIMP. Seventy percent of sixty-one detrital zircon ages from two schists ranges from 0.88 Ga to 3.09 Ga, mostly within 1.0 Ga to 1.8 Ga with a peak at 1.6 Ga to 1.8 Ga, and twenty percent varies from 2.0 Ga to 2.5 Ga. A few falls in the Archean and Neoproterozoic periods. The two granitic gneisses were dated 930±8 Ma and 918±14 Ma, whereas the mylonized granitic gneiss was dated 790±12 Ma. These ages represent two periods of magmatisms, which can be correlated with the early and late stages of magmatisms associated with the Jinningian movement on the Yangtze Blocks.