Geochronology and Geochemistry of Early Mesozoic Acid Volcanic Rocks from Southwest Guangxi : Constraints on Tectonic Evolution of the Southwestern Segment of Qinzhou-Hangzhou Joint Belt
详细信息
- 责任者：Qin Xiaofeng (Institute of Mineral Resources ; Chinese Academy of Geological Sciences ; Beijing 100037 ; China) ; Wang Zongqi
- 刊名：Acta Petrologica Sinica
- 出版年：2011
- 卷期：27(3)
- 关键词：酸性岩 ; acidic rocks ; 构造演化 ; structural evolution ; 广西 ; Guangxi
- 页码：p.794-808
- 图表：9 illus., 4 tables, 65 refs.
- 分类号：0801
- 出版序号：20120152
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
Early Mesozoic acid volcanic rocks are exposed dominantly in the southwestern segment of Qinzhou-Hangzhou joint belt, and are mainly distributed in both sides of the Shiwandashan Mesozoic-Cenozoic basin. The volcanic rocks of Lower and Middle Triassic Beisi Formation are exposed in northwest side of the basin, which consists of alternating volcanic succession of felsic lavas (basaltic andesite-dacite-rhyolite) interlayered with pyroclastic rocks (dominantly agglomerate lava, breccia lava, tuffolava, breccia ignimbrites, ignimbrites) and a dacite sample yielded a zircon SHRIMP U-Pb concordia age of (246±2) Ma. The volcanic rocks of Triassic Banba Formation are exposed in southeast side of the basin, which composed mainly of rhyolite interlayered perlite, tuffolava, agglomerate lava and rhyolite tuff and a rhyolite sample yielded a zircon SHRIMP U-Pb concordia age of (250±2) Ma. Such signatures display geochemical characteristics of typical subduction-related arc volcanic rocks.
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