从郯庐断裂带两侧的“盆”“山”耦合演化看前白垩纪“郯庐断裂带”的性质

    The nature of the pre-Cretaceous “Tanlu fault zone” viewed in the light of basin-range coupling evolution on its both sides

    • 摘要: 郯庐断裂带的前身是3条重要的边界断裂(古郯庐断裂、辽渤断裂和敦化-密山断裂),因而前白垩纪其两侧的“盆”“山”发育分属不同的造山动力学和成盆动力学系统。其西,扬子微大陆与华北微大陆之间的秦岭-大别造山带是印支期的碰撞造山带,兴-蒙造山带是海西期的阿尔泰型(增生弧型)造山带,燕山运动时两者都成为陆内造山带。“郯庐断裂带”以东,苏鲁造山带是苏皖地块与胶辽微大陆之间的燕山期碰撞造山带,延吉-清津造山带是胶辽微大陆与兴凯地块之间的印支期碰撞造山带;更北则是由一系列外来地体沿敦化-密山断裂拼贴在西伯利亚次大陆之上而形成的斜向汇聚-剪切造山带(属板间造山带)。在此基础上,分为海西—印支期、侏罗纪和白垩纪3个时代,详细剖析了“郯庐断裂带”两侧与上述造山作用耦合的典型的磨拉石盆地和火山岩盆地的演化及其对比,证实前白垩纪“郯庐断裂带”两侧的盆地各有其独立的发育史,不是被郯庐断裂带左行平移错断的同一个盆地。对“郯庐断裂带”两侧古生代—三叠纪陆表海的研究进一步证实其西的扬子微大陆、华北微大陆、布列亚-佳木斯地块与其东的苏皖地块、胶辽微大陆、兴凯地块曾分属独立的构造单元。早白垩世时,随着新特提斯洋的部分闭合,亚洲大陆的雏形出现,上述3条边界断裂连接成郯庐断裂带并成为陆内的左行走滑断层。

       

      Abstract: The Tanlu fault zone is regarded as an intracontinental sinistral strike-slip fault. The predecessor of the fault zone was three important pre-Cretaceous boundary faults, the Paleo-Tanlu fault, Liao-Bo fault and Dunhua-Mishan fault; therefore the ranges and basins on its both sides belonged to different orogenic and basin-making dynamic systems. To the west of the fault zone, the Qinling-Dabie orogen between the Yangtze and the North China craton was an Indosinian collisional one, and the Hinggan-Mongolia (for short, Hing-Meng) orogen was a Hercynian Turkic-type (accretional arc-type) one. Both became intracontinental orogens during the Yanshanian movement. To the east of the fault zone, the Sulu orogen was a Yanshanides formed by collision between the Su-Wan block and Jiao-Liao craton; the Yanji-Chongjin orogen was an Indosinides formed by collision between the Jiao-Liao craton and Khanka block; and farther northwards, there occurred an oblique convergence-shear orogen (interplate orogen) resulting from amalgamation of a group of allochthonous terranes on the Siberian subcontinent along the Dunhua-Mishan fault. Based on what are mentioned above, three generations (Late Paleozoic-Triassic, Jurassic and Cretaceous) of basins have been distinguished and the evolution of the orogeny-coupled molasse basins and volcanic basins on both sides of the Tanlu fault zone have been analyzed. The comparative study confirms that the basins on both sides of the pre-Cretaceous Tanlu fault zone have their respective unique evolutional histories, rather than belonged to the same basin displaced sinistrally by the Tanlu fault zone. The study of the Paleozoic-Triassic epicontinental sediments on both sides of the fault further demonstrates that the Yangtze and North China cratons and Burean-Jiamusi block to the west of the fault zone had once been independent of the Su-Wan block, Jiao-Liao craton and Khanka block to the east. With the closure of part of the Neo-Tethyan oceanic basins in the Early Cretaceous, the embryonic form of the Asian continent appeared. The above-mentioned three boundary faults linked up each other and became an intracontinental sinistral strike-slip fault (the Tanlu fault zone), and then the regional tectonic evolution on both sides of the fault zone tended to be uniform.

       

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