SHRIMP zircon U-Pb dating for volcanic rocks of the Dasi Formation in southeast Hubei Province, middle-lower reaches of the Yangtze River and its implications |
| |
摘 要: | The Jinniu Basin in southeast Hubei,located at the westernmost part of middle-lower val-ley of the Yangtze River,is one of the important vol-canic basins in East China. Volcanic rocks in the Jin-niu Basin are distributed mainly in the Majiashan Formation,the Lingxiang Formation and the Dasi Formation,consisting of rhyolite,basalt and basaltic andesite,(trachy)-basalt and basaltic trachy-andesite and (trachy)-andesite and (trachy)-dacite and rhyolite respectively,in which the Dasi volcanism is volumet-rically dominant and widespread. The Dasi volcanic rocks were selected for SHRIMP zircon U-Pb dating to confirm the timing of volcanism. The results indi-cate that there exist a large amount of magmatic zir-cons characterized by high U and Th contents in the volcanic rocks. The concordia ages for 13 points are 128 ± 1Ma (MSWD = 3.0). On account of the shape of zircons and Th/U ratios,this age is considered to represent the crystallization time of the Dasi volcan-ism. The volcanic rocks in the Dasi,Majiashan and Lingxiang Formations share similar trace elementand REE partition patterns as well as Sr-Nd isotopic compositions. In combination with the regional geol-ogy,it is proposed that the southeast Hubei volcanic rocks were formed mainly during the Early Creta-ceous,just like other volcanic basins in middle-lower Yangtze valley. A lithospheric extension is also sug-gested for tectonic regime in this region in the Cre-taceous Period.
|
关 键 词: | 火山岩 SHRIMP锆石U-Pb测年 湖北东南部 地质构造 年代学 长江中下游地区 |
收稿时间: | 2006-01-04 |
修稿时间: | 2006-04-28 |
SHRIMP zircon U-Pb dating for volcanic rocks of the Dasi Formation in southeast Hubei Province, middle-lower reaches of the Yangtze River and its implications |
| |
Authors: | Guiqing Xie Jingwen Mao Ruiling Li Shaodong Zhou Huishou Ye Quanren Yan Zusong Zhang |
| |
Institution: | (1) State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing, 100083, China;(2) Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing, 100037, China;(3) Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550002, China;(4) No. 4 Geological Party of Hubei Province, Xianning, 437100, China;(5) Institute of Geology, Chinese Academy of Geosciences, Beijing, 100037, China;(6) Southeast Hubei Geological Party of Hubei Province, Daye, 435100, China |
| |
Abstract: | The Jinniu Basin in southeast Hubei, located at the westernmost part of middle-lower valley of the Yangtze River, is one of
the important volcanic basins in East China. Volcanic rocks in the Jinniu Basin are distributed mainly in the Majiashan Formation,
the Lingxiang Formation and the Dasi Formation, consisting of rhyolite, basalt and basaltic andesite, (trachy)-basalt and
basaltic trachy-andesite and (trachy)-andesite and (trachy)-dacite and rhyolite respectively, in which the Dasi volcanism
is volumetrically dominant and widespread. The Dasi volcanic rocks were selected for SHRIMP zircon U-Pb dating to confirm
the timing of volcanism. The results indicate that there exist a large amount of magmatic zircons characterized by high U
and Th contents in the volcanic rocks. The concordia ages for 13 points are 128 ± 1Ma (MSWD = 3.0). On account of the shape
of zircons and Th/U ratios, this age is considered to represent the crystallization time of the Dasi volcanism. The volcanic
rocks in the Dasi, Majiashan and Lingxiang Formations share similar trace element and REE partition patterns as well as Sr-Nd
isotopic compositions. In combination with the regional geology, it is proposed that the southeast Hubei volcanic rocks were
formed mainly during the Early Cretaceous, just like other volcanic basins in middle-lower Yangtze valley. A lithospheric
extension is also suggested for tectonic regime in this region in the Cretaceous Period. |
| |
Keywords: | zircon SHRIMP dating Dasi Formation volcanic rocks Jinniu Basin Yangtze River |
本文献已被 万方数据 SpringerLink 等数据库收录! |
| 点击此处可从《中国科学通报(英文版)》浏览原始摘要信息 |
| 点击此处可从《中国科学通报(英文版)》下载免费的PDF全文 |
|