桂北地区丹洲群锆石U-Pb年代学及对华南新元古代裂谷作用期次的启示

发布时间：2018-03-16 00:25

本文选题：桂北地区　切入点：丹洲群　出处：《大地构造与成矿学》2016年05期 　论文类型：期刊论文

【摘要】：桂北地区丹洲群是南华裂谷盆地南段的一套连续裂谷充填沉积,厘定各组沉积时限及区域地层关系,对理解华南新元古代裂谷作用期次具有重要意义。本文利用LA-ICP-MS锆石U-Pb同位素测年,获得丹洲群合桐组二段和拱洞组底部凝灰岩夹层形成年龄分别为801±4 Ma和781±5 Ma。研究表明,丹洲群白竹组和合桐组一段与下江群甲路组和乌叶组、板溪群沧水铺组和马底驿组、西乡群孙家河组及陆良组一段相当,沉积时限为820~800 Ma;合桐组二段与下江群番召组相当,沉积时限为800~780 Ma;拱洞组可与下江群清水江组、平略组和隆里组,板溪群五强溪组中上部和牛牯坪组,西乡群大石沟组中上部和三郎铺组,陆良组二段及澄江组、开建桥组、莲沱组、虹赤村组和上墅组的中上部直接对比,沉积时限为780~725 Ma。华南新元古代裂谷盆地系统的典型地层锆石年龄存在5组高峰,峰值年龄分别为818±2 Ma、802±1 Ma、780±4 Ma、756±4 Ma及728±5 Ma。综合华南新元古代岩浆活动特征及盆地沉积演化过程,确定华南新元古代裂谷作用可分为两期:820~800 Ma和800~725 Ma。此外,华南新元古代岩浆活动与裂谷作用之间存在明显的耦合关系,但各期岩浆活动对各裂谷盆地的影响程度存在差异。
[Abstract]:The Danzhou Group in northern Guangxi is a set of continuous rift filling deposits in the southern part of the South China Rift Basin. The time limit of each group and the regional stratigraphic relationship are determined. It is of great significance to understand the Neoproterozoic rifting stages in South China. Using LA-ICP-MS zircon U-Pb isotopic dating, the ages of tuff intercalation in the second member of Hetong formation and Gongdong formation are 801 卤4 Ma and 781 卤5 Ma, respectively. The results show that the age of tuff intercalation is 801 卤4 Ma and 781 卤5 Ma, respectively. The first member of the Baichutong formation of the Danzhou group is equivalent to that of the Lower Jiangqun Group, the Wuye formation, the Cangshuipu and Madiyi formations of the Banxi Group, the first member of the Sunjiahe formation and the Luliang formation of the Xixiang Group, and the sedimentary time is 820 ~ 800 Ma.The second member of the Hetong formation is equivalent to the Panzhao formation of the Lower Yangtze Group. The sedimentary time limit is 800yun780 Ma.The Gongdong formation can be combined with Qingshuijiang formation, Pinglio formation and Longli formation of Xijiang group, middle and upper part of Wuqiangxi formation and Niuguping formation of Banxi group, middle and upper part of Dashigou formation, second member of Luliang formation and Chengjiang formation, Kaijianqiao formation, Dashigou formation, Luliang formation and Chengjiang formation of Xixiang Group. Liantuo formation, Hongchicun formation and Shangshu formation have direct correlation in the upper and middle parts, and the sedimentary time is 780,725 Ma.The zircon ages of the typical strata of the Neoproterozoic rift basin system in South China have 5 sets of peaks. The peak age is 818 卤2 Ma 802 卤1 Ma, 780 卤4 Ma 756 卤4 Ma and 728 卤5 Ma, respectively. According to the characteristics of Neoproterozoic magmatism in South China and the sedimentary evolution of the basin, it is determined that the Neoproterozoic rift in South China can be divided into two stages: 820 ~ 800 Ma and 800 ~ 725 Ma. There is an obvious coupling relationship between Neoproterozoic magmatic activity and rift valley in South China, but the influence of magmatic activity on each rift basin is different in different periods.
【作者单位】：中国地质调查局成都地质调查中心;成都理工大学沉积地质研究院;国土资源部沉积盆地与油气资源重点实验室;中国地质科学院;
【基金】：国家自然科学基金项目(41502114、41402103、41030315) 中国地质调查局项目(121201010000150016-02、121201010000150002-09) 成都地质调查中心青年基金项目(2015-09)联合资助
【分类号】：P597.3;P534.3

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