Zircon Geochronology and Lu-Hf Isotope Compositions for Precambrian Rocks of the Dunhuang Complex in Shuixiakou Area, Gansu Province
详细信息
- 责任者：Zhao Yan (State Key Laboratory of Continental Dynamics ; Department of Geology ; Northwest University ; Xi’an 710069 ; China) ; Diwu Chunrong
- 刊名：Acta Petrologica Sinica
- 出版年：2013
- 卷期：29(5)
- 关键词：杂岩 ; complexes ; 片麻岩 ; gneisses ; 铀—铅计时 ; U-Pb dating ; 甘肃 ; Gansu Province
- 页码：p.1698-1712
- 图表：illus., 2 tables, 61 refs.
- 分类号：0802
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
Dunhuang block is located in the southeast of Tarim Craton,and the research of Precambrian Dunhuang complex is of great significance in investigating the formation and evolution of the crust of Dunhuang block,as well as its tectonic relationship with the North China Craton and Yangtze Craton. Dunhuang complex,in Shuixiakou area,Gansu Province,mainly consists of tonalitic-granodioritic gneisses,granitic gneisses and metamorphosed supracrustal rocks. The age of 2561 ± 16Ma and 2510 ± 22Ma respectively for the tonalitic and the granitic gneisses by LA-ICP-MS U-Pb dating of zircons confirm the existence of Archean rocks in Dunhuang complex,LA-ICP-MS U-Pb dating of zircons yielded a metamorphic age of 1806 ± 14Ma for the amphibolite,and its parent magma probably derived from the partial melting of ancient lithospheric mantle. Based on the integration of our study and the available data, we put forward that Dunhuang complex has experienced a metamorphism during the Late Paleoproterozoic ( 1. 80 ～ 1. 85Ga) . The analysis of Hf isotopes of zircons indicates that ～ 2. 5Ga is a major period of crustal growth in Dunhuang block during the Neoarchean, while the ～ 1. 8Ga tectonic-thermal event represent a reworking period of ancient crust. The above data show that the formation and evolution of Dunhuang block is similar with the North China Craton during Early Precambrian,and they are involved in the global collision-orogenic event during Columbia Period.