| 南盘江盆地南缘富宁—那坡地区早—中三叠世火山-沉积组合形成环境 |
| |
| 引用本文： | 向忠金,闫全人,夏磊,夏文静.南盘江盆地南缘富宁—那坡地区早—中三叠世火山-沉积组合形成环境[J].地质通报,2021(1). |
| |
| 作者姓名： | 向忠金 闫全人 夏磊 夏文静 |
| |
| 作者单位： | 中国地质科学院地质研究所;自然资源部深地动力学重点实验室;中国科学院大学地球与行星科学学院;云南大学地球科学学院;北京航空航天大学学生处 |
| |
| 基金项目： | 中国地质调查局项目《钦杭西南段及邻区古特提斯造山区区域地质专项调查》(编号:12120113067500)、《云南省洞波幅和皈朝幅1∶5万区域地质调查》(编号:DD20160201-7);自然资源部深地动力学重点实验室自主研究课题《中越边境上二叠统—下三叠统碎屑岩物源和形成构造环境研究》(编号:J1901-24)。 |
| |
| 摘 要： | 南盘江盆地南缘发育大量早—中三叠世岩浆岩和巨厚三叠系,为研究沿中越边界一带是否发生洋盆俯冲消亡过程提供了重要的岩浆-沉积证据。选取中越边界地区出露面积最大的富宁—那坡地区早—中三叠世火山岩及相关沉积作为研究对象,通过系统的地质填图和剖面测量,查明这套火山-沉积组合具有下部玄武安山岩,上覆碳酸盐岩质砾岩、含砾粗砂岩和钙质砂岩的沉积序列,与岛弧环境火山-沉积序列相似。玄武安山岩SHRIMP锆石U-Pb定年结果为247±1 Ma和246±3 Ma,与野外产于中三叠统碎屑岩之下的地质事实相符。结合前人研究成果,确定这套火山岩形成于早—中三叠世(247~242 M a)。全岩地球化学分析结果显示,玄武安山岩富集大离子亲石元素(LILEs,R b、T h和U)和轻稀土元素(LR EE),其具有明显的Nb、Ta和Ti负异常。火山-沉积序列和火山岩地球化学特征表明,富宁—那坡地区早—中三叠世火山-沉积组合形成于与俯冲相关的弧环境。中越边界地区早—中三叠世弧火山岩与蛇绿混杂岩带的时空展布特征表明,该地区晚古生代洋盆发生了向北的俯冲消减。
|
| 关 键 词： | 玄武安山岩 岛弧 三叠纪 南盘江盆地 华南 |
The tectonic setting of the Early-Middle Triassic volcanic-sedimentary succession in Funing-Napo area,the south margin of Nanpanjiang Basin,South China |
| |
| XIANG Zhongjin,YAN Quanren,XIA Lei,XIA Wenjing.The tectonic setting of the Early-Middle Triassic volcanic-sedimentary succession in Funing-Napo area,the south margin of Nanpanjiang Basin,South China[J].Geologcal Bulletin OF China,2021(1). |
| |
| Authors: | XIANG Zhongjin YAN Quanren XIA Lei XIA Wenjing |
| |
| Institution: | (Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resources,Beijing 100037,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;School of Earth Sciences,Yunnan University,Kunming 650500,Yunnan,China;Department of Student Affairs,Beihang University,Beijing 100191,China) |
| |
| Abstract: | The Late Paleozoic to Early Mesozoic tectonic evolution process along the Sino-Vietnam border,particularly the subduction polarity of the Late Paleozoic ocean basin,is still controversial.Massive Early—Middle Triassic magmatic rocks and thick Triassic siliciclastic system occurred in the south margin of Nanpanjiang Basin provide important magmatic and sedimentary evidences for settling dispute.The Funing-Napo Triassic volcanic rocks,as the largest magmatic outcrop,are the ideal object for studying the tectonic evolution along the Sino-Vietnam border.The systematic profile survey and geological mapping indicates that the volcanic-sedimentary succession that consists of lower basaltic andesites overlain by carbonate conglomerates,pebbly sandstones and calcareous sandstones,which is similar to the volcanic-sedimentary sequence in island arc setting.Zircon SHRIMP U-Pb dating results of basaltic andesites are 247±1 Ma and 246±3 Ma,which are consist with field occurrence that basaltic andesite is overlain by Middle Triassic clastic rocsk.Combined with previous results,it is determined that the volcanic rocks were formed at 247~242 Ma.The geochemical analysis shows that basaltic andesites are enriched in LILEs(Rb,Th and U)and LREE,with a remarkable negative Nb-Ta and Ti anomalies.Both the geochemical characteristics of basaltic andesites and the volcanic-sedimentary sequence suggest that the Early—Middle Triassic volcanic-sedimentary succession was formed in a subduction-related arc setting.The spatial and temporal distribution characteristics of Early-Middle Triassic volcanic arc and ophiolitic mélange,implies that a north-dipping subduction occurred along Sino-Vietnam border. |
| |
| Keywords: | basaltic andesite Island arc Triassic Nanpanjiang Basin South China |
| 本文献已被 维普 等数据库收录！ |
| 点击此处可从《地质通报》浏览原始摘要信息 |
| 点击此处可从《地质通报》下载免费的PDF全文 |
|
