Subdivision and Isotopic Age of Lengjiaxi Group in Hunan Province
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摘要: 依据区域岩石组合特征,参照岩石地层的划分原则,对冷家溪群进行重新划分:下部为海相深水盆地沉积细碎屑岩系,划分出易家桥组、潘家冲组、雷神庙组;上部为盆地斜坡相浊流(扇)沉积粗碎屑岩系,分为黄浒洞组、小木坪组、大药菇组。在冷家溪群各岩组中的凝灰岩夹层内取得一批新的SHRIMP锆石U-Pb测年数据,对其沉积时代归属提供了新的约束。锆石SHRIMP年龄数据表明其沉积时限介于820~〉862 Ma之间,时代属于新元古代早期。Abstract: According to regional rock assemblages and strata subdivision principle,Lengjiaxi Group can be subdivide into upper part of marine deep-water basin deposited fine clastic rocks(including Yijiaqiao Formation,Panjiachong Formation and Leishenmiao Formation) and lower part of basin slope turbidite deposited coarse clastic rocks(including Huangxudong Formation,Xiaomuping Formation and Dayaogu Formation).The zircons from tuff interlayers of every Formation of Lengjiaxi Fromation are tested by SHRIMP U-Pb dating method to constraint the sedimentary ages,which indicated that the sedimentary age of Lengjiaxi Group is between 820 to 862 Ma,and belongs to early Neoproterozoic.
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Key words:
- classification and correlation /
- Lengjiaxi Group /
- isotopic age /
- Neoproterozoic Era /
- Hunan province
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