ISSN 1006-3021 CN11-3474/P
Published bimonthly started in 1979
关键词:Alxa Block  Pre-Mesozoic  paleomagnetism  zircon U-Pb age  Hf isotope
基金项目:国家专项“深部探测技术与实验研究”(编号: SinoProbe08-01; 201011074)
杨振宇 中国地质科学院地质力学研究所, 国土资源部古地磁与古构造重建重点实验室 
袁伟 中国石化石油勘探开发研究院无锡石油地质研究所
仝亚博 中国地质科学院地质力学研究所, 国土资源部古地磁与古构造重建重点实验室  
刘静 江苏省有色金属华东地质勘查局  
王艳 中国地质科学院地质力学研究所, 国土资源部古地磁与古构造重建重点实验室  
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Tectonic Affinity Reconnaissance of the Alxa Block in the Pre-Mesozoic
      Tectonic affinity of the Alxa Block has long been a topic of much controversy. In this study, samples of Middle–Late Devonian sedimentary rocks were systematically collected from the Niushou Mountain in southeastern Alxa Block. The detrital zircon U-Pb ages define five age populations: 0.4–0.7 Ga, 1.0–1.3 Ga, 1.5–1.8 Ga, 2.4–2.7 Ga and >3.0 Ga. Zircons with U-Pb age spectra of 2.4–2.7 Ga, >3.0 Ga and their corresponding εHf(t) values are significantly different from data obtained from the North China Block, which implies that the Alxa Block was not part of North China until the Middle–Late Devonian. In addition, paleomagnetic study of the Late Devonian to Middle Triassic strata in the Niushou Mountain and the eastern part of the Alxa Block was carried out and, as a result, the apparent polar wander paths (APWP) were established. These results indicate that the Alxa Block had a close affinity with the Qaidam–Tarim Block, but was separated from the North China Block prior to the Pre-Mesozoic. The Alxa Block suffered from a counterclockwise rotation of 32° with respect to the North China Block during the Indosinian orogeny and finally amalgamated with the North China Block into a unified block before the Early Cretaceous.
YANG Zhen-yu,YUAN Wei,TONG Ya-bo,LIU Jing,WANG Yan.2014.Tectonic Affinity Reconnaissance of the Alxa Block in the Pre-Mesozoic[J].Acta Geoscientica Sinica,35(6):673-681.
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