SHRIMP Zircon U-Pb Age of Late Mesozoic Volcanic Rocks from the Chuzhou Basin, Eastern Anhui Province, and Its Geological Significance
详细信息
- 责任者：Ma Fang (School of Earth and Space Sciences ; Peking University ; Beijing 100871 ; China) ; Xue Huaimin
- 刊名：Acta Petrologica et Mineralogica
- 出版年：2011
- 卷期：30(5)
- 关键词：中生代 ; Mesozoic ; 火山岩 ; volcanic rocks ; 铀—铅计时 ; U-Pb dating ; 安徽 ; Anhui Province
- 页码：p.924-934
- 图表：5 illus., 2 tables, 68 refs.
- 分类号：0801
- 出版序号：202
- issnNo：ISSN1000-6524
- isbnNo：CN11-1966/P
摘要
The Chuzhou basin,one of the several late Mesozoic volcanic basins developed in the middle and lower reaches of the Yangtze River,is the only basin directly superimposed upon the Dabie orogenic belt,with relatively old basement composed of Neoproterozoic-lower Paleozoic strata.The volcanic rocks in the Chuzhou basin are mainly intermediate-acidic trachyandesite and trachydacite,which belong to high-K cal-alkaline series and greatly differ from most late Mesozoic volcanic basins in the middle and lower reaches of the Yangtze River such as Ningwu basin,Luzong basin,Lishui basin and Huaining basin which belong to the shoshonitic series in geochemistry.In this study,the authors used zircon SHRIMP U-Pb technique to perform accurate dating of a trachyandesitic sample from the Huangshiba Formation in the Chuzhou basin,which yielded an emplacement age of 128±1 Ma.This age is similar to the emplacement ages of volcanic/sub-volcanic rocks in other late Mesozoic volcanic basins,suggesting that the whole volcanism in the middle and lower reaches of the Yangtze River were developed in a very short period of time.The volcanic rocks in the Chuzhou basin have remarkably lower εNd(t)values than those in other volcanic basins but are similar to those of the late Mesozoic granitoid intrusive bodies in the Dabie orogen,indicating that their parent magma might have been mainly derived from partial melting of "old" lower crust.
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