鄂尔多斯盆地北部晚古生代沉积充填与兴蒙造山带“软碰撞”的耦合

Sedimentary Filling of North Ordos and Their Implications for the Soft Collision Process of Hing Gan Mts.-Mongolia Orogenic Belt in Late Paleozoic

鄂尔多斯盆地上古生界因大面积富砂成藏而越来越受关注。通过研究沉积充填特征、砂岩碎屑组分、火山沉积物与造山带的关系,认为晚古生代鄂尔多斯盆地北部与兴蒙造山带组成了一个不可分割的盆-山系统。6个超层序的沉积体系展布和层序结构反映了陆表海向陆内坳陷盆地的转化,砂岩组分的Dickinson投点图表明盆地充填物来自北缘再旋回造山带,多期次的火山沉积物暗示盆-山耦合过程中幔/壳圈层间的物质循环与调整。分析表明:晚石炭世—二叠纪初充填的小型河流-三角洲系统是拼合过程中古地体缓冲、间歇性裂谷作用和低幅隆升的结果;二叠纪发育的几期大型浅水河流-三角洲系统与造山带的碰撞加强和旋回性隆升相耦合。兴蒙造山带漫长复杂的俯冲碰撞造山过程充分体现了我国盆-山系统演化过程中小陆块拼合、软弱碰撞、多旋回缝合和陆内构造活动强烈的特点,是鄂尔多斯上古生界克拉通坳陷盆地大型缓坡地貌形成和大面积富砂成藏的关键因素。

Neopaleozoic of Ordos basin attracts more and more attention because of its blanket enriching sandstone and reservoir.We had studied the relationship between the sedimentary filling,sandstone component,volcanic sediment and orogenic belt,suggest that north Ordos basin and Hing Gan Mts.-Mongolia orogenic belt formed a indiscerptible orogen-basin system in Late Paleozoic.The sedimentary systems and sequence patterns of the six super sequence reveal the basin evolution from epeiric sea to intracontinental depression basin.Dickinson triplot of sandstone clastic component indicate the sediment come from north recycled-orogenic belt.volcanic sediment matter recorded the circulation and adjusting of crust-mantle matter.We suggest that small-scale river-dalta systems of Late Carboniferous-Earliest Permian owing to the terrain assembly,intermittence rifting and low-amplitude uplift,while big-scale river-dalta systems of Permian couple with collision strengthen and cyclicity uplift of the orogenic belt.The long-term complicated collision process reflected the characteristic of Chinese orogen-basin system,such as microcontinental amalgamation,soft collision,multi-cycle suturing and intensive intracontinental tectonic activities,it is significant for gentle slope forming and sand reservoir widely distribution in Upper Paleozoic ordos intercratonic depression basin.