- 责任者：Liu Dongdong (School of Earth and Space Sciences ; Peking University ; Beijing 100871 ; China) ; Guo Zhaojie
- 刊名：Geotectonica et Metallogenia
- 出版年：2013
- 卷期：37(3)
- 关键词：不整合 ; unconformities ; 铀—铅计时 ; U-Pb dating ; 天山 ; Tianshan Mountains
- 页码：p.349-365
- 图表：6 illus., 61 refs.
- 分类号：0300
- issnNo：ISSN1001-1552
- isbnNo：CN44-1595/P
A typical unconformity lies between the Permian Lucaogou Formation and Triassic Xiaoquangou Formation in the Aiweiergou area （Northern Xinjiang）, which suggests an important geological event. Several papers have been published concerning this unconformity with quite different views regarding the causes and significances. Based on previous studies, we have systematically analyzed the structure and sedimentary characteristics of the unconformity. Detrital zircon U-Pb analyses show that the age patterns between the underlying Upper Permian Lucaogou Formation and overlying Middle-Upper Triassic Xiaoquangou Formation are similar, both are near-unimodal. The results indicate that no great change of tectonic setting occurred during Late Permian and Late Triassic in the northern Tian Shan. Thus the prevalence views about the unconformity, such as standing for the closure of the North Tian Shan Ocean or regional compressional event, are incorrect. Based on previous studies and our U-Pb dating of the detrital zircons, we believe that the unconformity is a sedimentary unconformity, which was caused by further depression after asymmetric depression fault process of the basin. Such structural phenomenon was discovered and reported in many other places, like Chinese eastern basins and North Sea basin.