东北地区晚古生代区域构造演化
Late Paleozoic tectonic evolution in Northeast China
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摘要: 提要：东北地区主要由东部佳木斯地块、中部兴安—松嫩地块和西部额尔古纳地块构成，各地块之间主要构造带拼合时代的研究表明，晚古生代之前各地块之间已经完成拼合，形成了统一的佳—蒙地块。晚古生代开始东北地区进入统一的盖层演化阶段，在佳—蒙地块南缘发育了晚古生代具有大陆边缘沉积特征的盖层建造。晚古生代早期佳—蒙地块南缘为活动陆缘，在～320 Ma向北的俯冲过程中古亚洲洋板块发生断离，形成火山弧，同时导致其北侧“贺根山”弧后洋的拉开，持续的向北俯冲导致弧-陆碰撞，并于～280 Ma贺根山洋已经完全闭合。佳—蒙地块南缘开始由活动陆缘向被动陆缘环境转化，最后在晚二叠世末期古亚洲洋完全闭合转入内陆环境。Abstract: Abstract：Northeast China area consists of several micro-continental blocks, such as Jiamusi Block in the southeast, Xing’an-Songliao Block in the middle, and Erguna blocks in the northwest. Studies of the suture zones between the blocks indicate that the amalgamation of these blocks ended before Late Paleozoic and formed a big continental block, i.e., Jia-Meng Block. From Late Paleozoic the cover sequences started to develop and formed a Late Paleozoic continental margin cover sequence.The tectonic setting of the southern margin of the Jia-Meng Block was an active continental margin during early Paleozoic. The Paleo-Asian ocean plate broke down during the northward subduction around 320 Ma, and formed a volcanic arc. Meanwhile the Hegenshan back-arc basin ocean was opened. The continuous northward subduction resulted in the arc-continent collision, and the Hegenshan Ocean was closed at 280 Ma. The tectonic setting changed from active margin to passive margin. Finally the Paleo-Asian ocean was closed at the end of Late Permian, and the whole area became an intracontinental terrestrial setting.
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