Provenance and Tectonic Setting of Sandstone-Type Uranium Deposit in Dongsheng Area, Ordos Basin: Evidence from U-Pb Age and Hf Isotopes of Detrital Zircons
详细信息
- 责任者：Wang Meng (State Key Laboratory of Continental Dynamics ; Department of Geology ; Northwest University ; Xi’an 710069 ; China) ; Luo Jinglan
- 刊名：Acta Petrologica Sinica
- 出版年：2013
- 卷期：29(8)
- 关键词：铀矿 ; uranium ores ; 鄂尔多斯盆地 ; Ordos Basin
- 页码：p.2746-2758
- 图表：8 illus., 2 tables, 83 refs.
- 分类号：1001
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
Research result of provenance tracing and tectonic setting for sandstone-type uranium deposit in Zhiluo Formation of the Middle Jurassic in Dongsheng area,Ordos basin,using LA-(MC) ICP-MS in situ U-Pb dating and Hf isotope analysis of the detrital zircons from the sandstones indicates that zircon ages from four samples yield consistent characteristics,with three major age peaks at 2500 ～ 2300Ma,2000 ～ 1750Ma and 450 ～ 250Ma,and two subordinate age peaks at 2300 ～ 2000Ma and 1750 ～ 1400Ma. By comparative study of isotopic chronology with the potential parent rocks,it can be concluded that the provenance of the sandstone-type uranium deposit in Dongsheng area mainly came from the TTG genesis,granulite,khondalite and the Hercynian igneous bodies from Yinshan terrain in western block,and the northern part of the Trans-North Chian Orogen. The ε Hf(t) values of the detrital zircons vary in a wide range,from positive to negative,indicating a recycling of the old continent curst. Some Hf data points of the zircons with ages of ～ 1. 9Ga and ～ 2. 5Ga lie around the depleted mantle reference line in the εHf(t)-age figure,implying new crust formation from the mantle. The t DM2 values of the zircons vary from 3. 8Ga to 0. 7Ga,but cluster around 3. 0 ～ 2. 3Ga,with a peak at 2. 8 ～ 2. 6Ga, illustrating that crust of the North China Craton was formed mainly from Mesoarchean to Neoarchean. The research also shows that Hf isotopic model ages of the detrital zircons from the study area consistent with the published Hf and Nd isotopic model ages from the Western Block,but different from that of the Eastern Block,which is also an important direct evidence that the two blocks of the North China Craton developed independently from each other until they finally combined into one in the Late Paleoproterozoic.
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