Revelation of the Meso-Neoproterozoic Crust on the Southern Margin of the Central Asian Orogenic Belt: Chronology and Hf Isotope Tracer from Drilling-intersected Alkaline Granites, Northern Beishan-Alxa [中亚造山带南缘中-新元古代地壳的揭示-来自北山-阿拉善北部钻遇碱性花岗岩的年代学和Hf同位素示踪研究]

作者：Song B.; Zhang H.-Y.; Wei D.-T.; Li W.; Zhao F.; Li W.-M.

来源：Acta Geoscientica Sinica, 2021, 42(1): 9-20.

DOI：10.3975/cagsb.2020.071901

• Alkaline granite
• Alxa
• Beishan
• LA-ICP-MS
• Late Carboniferous
• Lu-Hf
• Microcontinent
• Zircon U-Pb

The Precambrian microcontinent is an important component of the northern Beishan-Alxa accretionary orogenic belt. Much controversy exists regarding the Precambrian basement of the Hanshan, Yagan and Zhusileng-Hangwula. Juyanhai is located between the northern part of the Beishan Orogenic Belt and the northern margin of the Alxa block. It is restricted by the Badain Jaran Desert and has very few rock outcrops. The authors drilled a set of Late Carboniferous alkaline granites. The zircon LA-ICP-MS U-Pb chronology and Hf isotope characteristics reveal that the granitic magma has zircon crystallization ages of (312 ± 1) Ma and (315 ± 2) Ma, and has positive εHf(t) values between + 0.8 and + 4.4, +2.2 on average, corresponding to the two-stage model age (TDM2) of 1048 ~ 1267 Ma, with average value being 1183 Ma. The ancient crust contributed the granitic magma. Based on comparing the Late Carboniferous granitoids with the Hanshan tectonic Belt, Queershan tectonic Belt, Yagan tectonic Belt, and Zhusleng-Hangwula tectonic Belt, the authors analyzed the Meso-Neoproterozoic crust in northern Beishan-Alxa. Additionally, based on the outcrops of 0.9 Ga granitic rocks and the regional interpretation of gravity and magnetic data, the authors infer that the Hanshan, Yagan and Zhusileng-Hangwula tectonic belts assembled together, and further conjunction can be carried out.

• 单位
  中国科学院大学