陈柏林. 阿尔金山北缘恰什坎萨依地区逆冲推覆构造的发现及其构造意义[J]. 地质通报, 2018, 37(2-3): 337-344.
    引用本文: 陈柏林. 阿尔金山北缘恰什坎萨依地区逆冲推覆构造的发现及其构造意义[J]. 地质通报, 2018, 37(2-3): 337-344.
    CHEN Bailin. The discovery of thrust nappe structure in Qiashikansayi area on the northern margin of Altun Mountains and its tectonic significance[J]. Geological Bulletin of China, 2018, 37(2-3): 337-344.
    Citation: CHEN Bailin. The discovery of thrust nappe structure in Qiashikansayi area on the northern margin of Altun Mountains and its tectonic significance[J]. Geological Bulletin of China, 2018, 37(2-3): 337-344.

    阿尔金山北缘恰什坎萨依地区逆冲推覆构造的发现及其构造意义

    The discovery of thrust nappe structure in Qiashikansayi area on the northern margin of Altun Mountains and its tectonic significance

    • 摘要: 阿尔金山北缘恰什坎萨依地区位于北东向阿尔金走滑断裂北侧与东西向阿尔金北缘断裂夹持的区域,是区域上红柳沟-拉配泉构造带的西段。该区广泛发育火山沉积岩系,前人将其确定为奥陶系拉配泉群,并划分为下岩组(火山岩组)、中岩组(碎屑岩组)和上岩组(碳酸盐岩组)。通过野外地质调查与局部填图,在恰什坎萨依沟、沟口泉铁矿、贝壳滩等地,发现厚层碳酸盐岩以不规则顶盖状出露在较高山顶或山脊上,并与碎屑岩或火山岩呈低角度断层接触关系,构成典型的飞来峰构造。该火山岩组和碎屑岩组已被归为奥陶系,但碳酸盐岩组一直没有精确的生物地层年代依据。综合研究认为,碳酸盐岩应该属中元古界,原来的拉配泉群可能要解体。结合截切推覆构造的冰沟岩体时代,认为推覆构造形成于中-晚奥陶世。该认识与本区在中-晚奥陶世发生裂谷(弧后盆地或有限洋盆)闭合、板块碰撞的区域构造环境和演化历史吻合。

       

      Abstract: The Qiashikansayi area of Altun Mountains is located in the western segment of Hongliugou-Lapeiquan structural belt, which is bounded by the NE-trending Altun strike-slip faults to the north and EW-trending northern Altun fault. There volcanic-sedimentary rocks are well developed, which are assigned to Lapeiquan Group and divided into three formations:the lower formation (volcanic rock formation), medium formation (fragmental rock formation) and upper formation (carbonate rock formation). Based on the field study and mapping in Qiashikansayi gully, Goukouquan iron ore area and Beiketan area, the author discovered a series of thick bedded carbonate rocks as an irregular top cover outcropped at high hills or ridge of hills and contacting with fragmental rock or volcanic rock under them by lower angle fault, which constitute the typical thrust outlier structure. The volcanic rock and fragmental rock are dated as Ordovician, while the thick bedded carbonate rocks are not dated by any accurate biostratigraphic or chronologic evidence. It is very probable that thick bedded carbonate rocks may be of Meso-Proterozoic period and the Lapeiquan Group was broken up into two parts:one was a new Lapeiquan Group (only consisting of volcanic rock formation and fragmental rock formation), and the other was carbonate rocks formation of Meso-Proterozoic period. According to the age of Binggou granite body which cut off the thrust nappe structural zone, the author considers that the thrust nappe formed in Middle to Late Ordovician epoch (about 460Ma). All these features are identical to specious tectonic setting of the closure of the Hongliugou-Lapeiquan rift (or back-arc basin or limited ocean basin) and of the collision belt of convergent plate in Middle to Late Ordovician epoch and their evolution history.

       

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