地学前缘 ›› 2018, Vol. 25 ›› Issue (1): 33-46.DOI: 10.13745/j.esf.yx.2017-5-13

• 华南中、新生代构造作用 • 上一篇    下一篇

八渡复式背斜中—新生代变形序列及其对南盘江盆地形成演化的意义

杨文心,颜丹平,邱亮,陈峰,木红旭,汪新文   

  1. 1. 中国地质大学(北京) 地球科学与资源学院, 北京 100083
    2. 中国地质大学 地质过程与矿产资源国家重点实验室, 北京 100083
  • 收稿日期:2016-12-01 修回日期:2017-02-24 出版日期:2018-01-15 发布日期:2018-01-15
  • 作者简介:杨文心(1993—),女,硕士研究生,构造地质学专业,主要从事区域构造解析等研究。E-mail:verseyang@cugb.edu.cn
  • 基金资助:
    国家重点基础研究发展计划“973”项目(2014CB440903);国家自然科学基金项目(41372212,41672216)

The Mesozoic-Cenozoic deformation sequences of the Badu complex anticline and their significance for the evolution of the Nanpanjiang Basin

YANG Wenxin,YAN Danping,QIU Liang,CHEN Feng   

  • Received:2016-12-01 Revised:2017-02-24 Online:2018-01-15 Published:2018-01-15

摘要: 南盘江盆地处于华南地块与印支地块的结合部位,前人认为其属于印支造山带的前陆盆地。但南盘江盆地在经历了中—新生代多期的叠加改造后,构造样式复杂,其中复式褶皱普遍发育。因此,文中选择南盘江盆地中部的八渡穹隆状复式背斜作为研究对象,将地表构造解析、深部地震剖面解释以及辉绿岩侵位年代限定结合,通过构造样式与构造组合分析,厘定构造变形序列。结果表明,八渡复式背斜是轴迹向北凸出的弧形复式背斜,以泥盆系为核,石炭—三叠系为翼。在深部发育指向NE的双重逆冲构造;中浅部发育指向N的逆冲叠瓦扇及断层褶皱构造。对侵位其中的辉绿岩进行定年,得到样品中最年轻的锆石颗粒年龄约为62 Ma,有可能与区域在这一阶段的缓慢加速隆升相关。综合分析八渡复式背斜不同层次构造样式,将研究区整体的变形序列大致划分为3期:第1期为印支运动早期板块俯冲背景下形成的双重逆冲构造,第2期是印支运动晚期板块碰撞形成的逆冲叠瓦扇等,第3期为燕山晚期伸展背景下辉绿岩的侵位和一系列正断层。八渡复式背斜形成演化过程在南盘江盆地叠加构造中具有典型代表性,体现了印支运动的前陆盆地先后经历了印支期俯冲碰撞、燕山期构造背景由压性向张性的转换,和新生代伸展隆升的过程。

关键词: 南盘江盆地, 复式背斜, 变形序列, 地震剖面解释, 辉绿岩, 锆石U-Pb年龄

Abstract: The Nanpanjiang Basin, located at the junction of the South China and Indochina blocks, is regarded as the foreland basin of Indosinian orogen. Due to the MesozoicCenozoic tectonic superimposition, the structural style of the basin is complex as superposed folds are common. Accordingly, the Badu domelike complex anticline in the middle of the Nanpanjiang Basin was chosen as the study object. Combining surface deformation analysis with deeper seismic profile interpretation and zircon geochronology of diabase, we reconstructed the structural styles and deformation sequences. The Badu complex anticline, which has a Devonian core and limbs of Permian and Triassic, is an arcshaped fold with northward axis. At the deep level, the structure is dominated by a NEdirecting duplex; at the middle and shallow level, there are Ndirected imbricates with faultrelated folds. The magmatic zircon from diabase yielded a youngest age population of 62 Ma, indicating a possible contemporaneous uplifting. Integrating structural styles at different levels, the deformation sequence of the region was divided into three deformations, D1, D2 and D3. D1, the duplex, was caused by Indosinian subduction; D2, the imbricate, was a result of Indosinian compression; and D3, represented by normal faults and diabase dykes, was a result of the Late Yanshanian extension. The formation and evolution of the Badu complex anticline is a typical example of the superimposition of the Nanpanjiang foreland Basin, which shows that the foreland basin of Indosinian underwent subduction, compression, tectonic transition from compression to extension during the Yanshanian, and finally uplifting in the Cenozoic era.

Key words: Nanpanjiang Basin, complex anticline, deformation sequence, seismic profile, diabase, zircon U-Pb age

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