Detrital-Zircon Geochronology from the Metasedimentary Rocks of the Suizhou Group in the Southern Foot of the Tongbaishan Orogen and Their Geological Significance
详细信息
- 责任者：Xue Huaimin (Institute of Geology ; Chinese Academy of Geological Sciences ; Beijing 100037 ; China) ; Ma Fang
- 刊名：Acta Petrologica Sinica
- 出版年：2013
- 卷期：29(2)
- 关键词：变沉积岩 ; metasedimentary rocks ; 碎屑沉积物 ; clastic sediments ; 桐柏山 ; Tongbai Mountains
- 页码：p.564-580
- 图表：illus., 1 table, 58 refs.
- 分类号：0802
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
The Suizhou-Zaoyang area (northern margin of the Yangtze Craton), the least affected area of the whole Qinling-Tongbaishan-Dabieshan-Sulu orogen and their foreland by the deep subduction of the Yangtze Craton beneath the North China Craton and concomitant HP-UHP metamorphism during Triassic, relatively well preserved Precambrian basement of the northern Yangtze Craton. These low-grade metamorphosed Precambrian rocks not only provide an ideal opportunity to study the palaeo-tectonic setting of the northern Yangtze Craton, but also are rare-references for resuming protolithes of the metamorphic complex in the orogen. The Precambrian rocks exposed here include Neoproterozoic volcanic-sedimentary rock series (Suizhou Group) and voluminous Neoproterozoic ultramafic-mafic sill swarms. In this work, we used LA-ICP-MS zircon U-Pb technique dating detrital zircons from the metasedimentary samples of the Suizhou Group, yielding results as follow: ① The youngest age of detrital-zircon from the metasediments of the Suizhou Group is about 720Ma, which means that the formed age of the Suizhou Group was mainly later than this time; ② Zircon grains with ages from about 700Ma to 1000Ma are maximum detrital zircon group, with peak value at about 800Ma, showing that the magmatic rocks formed in Neoproterozoic era, especially medium to late stage of the Neoproterozoic, were foremost source of the Suizhou Group; ③ There are many zircon grains with ages from 1700Ma to 2100Ma, showing that the magmatic rocks formed in the medium to late stage of the Paleoproterozoic were also one of important sources; ④ Existing of detrital-zircon with ages of early stage of Paleoproterozoic and Archaean imply that this era of stratum may exist in the northern margin of the Yangtze Craton.
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