东天山觉罗塔格地区夹白山一带晚古生代构造格局及演化
Late Paleozoic tectonic framework and evolution in the Jiabaishan area, Qoltag, eastern Tianshan Mountains, Northwest China
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摘要: 研究区早石炭世经历了中天山古陆北缘被动陆缘向活动陆缘沟弧盆体系演化的全过程。阿齐山一雅满苏岛弧带于维宪期发育在广宽陆棚海之上。岛弧为大型背形结构，雅满苏断裂带为火山喷发的主要通道，弧前盆地生成于弧沟间隙部位。晚石炭世早期，弧后区发生扩张作用而塌陷形成向形的边缘盆地。晚石炭世末，北侧康古尔洋区以弧弧对接方式关闭，弧区伴有深成花岗岩浆侵位。早二叠世早期进入松弛阶段，在弧间及弧后南缘产生上叠断陷盆地。晚二叠世右旋走滑变动席卷全区，最后大型造山带与地块之间发生块体右旋滑移错位，由此奠定了现今的盆山构造格局初貌。Abstract: The study area experienced the whole process of evolution from the passive to active continental-margin trencharc-basin systems on the northern margin of the central Tianshan old land in the Early Cretaceous. The Aqishan-Yamansu island-arc belt occurred on a wide continental shelf sea in the Visean Stage. The island arc has a large antiform structure, the Yamansu fault belt is a main conduit for volcanic eruption, and the forearc basin was formed in an arc-trench gap. In the early Late Carboniferous, collapse due to spreading .in the back-arc area led to the formation of a synformal marginal basin. At the end of the Late Carboniferous, the Kanggur Ocean on the northern side closed in the form of arc-arc junction, accompanied by emplacement of granitic magma in the arc area. The early Lower Permian was a relaxation stage, when an overlapped downfaulted basin formed in the interarc area and on the southern margin of the back-arc area. In the Late Pennian, the right-lateral strike-shp motion swept the whole region. Finally, tight-lateral slip displacement took place between the large-scale orogenic belt and the block, thus giving rise to the initial basin-range framework as now.
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