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    昆仑造山带二叠纪岩相古地理特征及盆山转换探讨

    The Permian lithofacies paleogeographic characteristics and basin-mountain conversion in the Kunlun orogenic belt

    • 摘要: 提要:昆仑造山带基本构造-地层格架主要奠基于古生代,是早古生代和晚古生代多次洋陆转换、碰撞造山的结果。早中二叠世是晚古生代昆仑多岛洋盆(昆南洋)伸展裂陷最为强烈期,海相沉积广布,昆北为活动边缘裂谷,大部分区域为滨浅海相沉积,局部为火山盆地相沉积;昆中洋岛大部分为海水淹没,发育滨浅海相沉积;康西瓦—木孜塔格—阿尼玛卿一线及其以北昆南区为深海-半深海相沉积。早中二叠世总体表现为南深北浅的多岛小洋盆构造-古地理格局。中二叠世晚期昆仑地区发生了一次显著的汇聚作用(华力西运动),洋盆和活动大陆边缘裂谷闭合,隆升遭受剥蚀,完成了一次盆山转换。晚二叠世早期,大部分地区仍为剥蚀区,局部地区形成陆相红色碎屑岩建造,其后东昆仑东部海水从东南进入,西昆仑东部海水从西北进入,在较局限的区域内沉积了滨浅海相碎屑岩和碳酸盐岩沉积,进入了另一个盆山发展时期。笔者通过多年的野外观察、分析测试和综合研究,结合覆盖全区的1∶25万区域地质调查资料及其他前人研究成果,选择昆仑造山带晚古生代盆山转换关键时期——二叠纪,对其地层、岩相特征及构造古地理环境进行研究,并探讨了其构造演化,以期对提高昆仑造山带的研究水平和指导找矿工作有所禆益。

       

      Abstract: Abstract:The Kunlun orogenic belt was basically formed in Paleozoic, resulting from ocean-continent conversion and collision orogenic activity. In the early and middle Permian, the south Kunlun was a multi-island ocean basin, the north Kunlun was an active margin rift and contained mainly shallow sea sediments and partly volcanic basin sediments, the middle part was a seashore-shallow sea, and the Kangxiwa-Muztagh-Animaqing belt contained deep-semi-deep sediments and formed a multi-island ocean basin paleogeographic framework in this period. In the middle and late Permian, convergence took place, ocean basin and active margin rift were closed, uplifting began, and basin-mountain conversion was completed. In the late Permian, the Kunlun orogenic belt entered into another basin-mountain conversion period, sea water came from southeast in the east part and from northwest in the west part, with the deposition of seashore- shallow sea fragmental rocks and carbonate rocks in local areas. Based on field work, analytical tests and integrated studies in association with the 1:250 000 regional geological data and other data available, the authors chose the Permian strata of late Palaeozoic as the study object and discussed the Permian lithofacies characteristics and tectono-paleogeography with the purpose of improving the research level of the Kunlun orogenic belt.

       

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