张天宇, 樊双虎, 陈淑娥, 李荣西. 鄂尔多斯地块西南缘千河水系变迁与新构造运动[J]. 地质通报, 2022, 41(2-3): 282-295. DOI: 10.12097/j.issn.1671-2552.2022.2-3.008
    引用本文: 张天宇, 樊双虎, 陈淑娥, 李荣西. 鄂尔多斯地块西南缘千河水系变迁与新构造运动[J]. 地质通报, 2022, 41(2-3): 282-295. DOI: 10.12097/j.issn.1671-2552.2022.2-3.008
    ZHANG Tianyu, FAN Shuanghu, CHEN Shu'e, LI Rongxi. Evolution of Qian River system and neotectonic movement in the southwest margin of Ordos Block[J]. Geological Bulletin of China, 2022, 41(2-3): 282-295. DOI: 10.12097/j.issn.1671-2552.2022.2-3.008
    Citation: ZHANG Tianyu, FAN Shuanghu, CHEN Shu'e, LI Rongxi. Evolution of Qian River system and neotectonic movement in the southwest margin of Ordos Block[J]. Geological Bulletin of China, 2022, 41(2-3): 282-295. DOI: 10.12097/j.issn.1671-2552.2022.2-3.008

    鄂尔多斯地块西南缘千河水系变迁与新构造运动

    Evolution of Qian River system and neotectonic movement in the southwest margin of Ordos Block

    • 摘要: 鄂尔多斯地块西南缘新构造运动活跃,其河流阶地发育过程和水系演化历史蕴藏了丰富的新构造运动信息。发育于鄂尔多斯西南缘的千河水系两岸不对称分布5级河流阶地,通过野外调查和钻探揭露,厘清了阶地结构和发育特征,利用电子自旋共振(ESR)测年、光释光(OSL)测年和黄土地层对比定年,分析了阶地形成的时代和下切速率,结合区域地质背景,探讨千河阶地发育和水系变迁的动力背景。研究结果表明,千河干流T5~T1阶地分别形成于1.176 Ma、0.766 Ma、0.504 Ma、0.131 Ma和0.04 Ma,各级阶地对应的下切速率分别为76.6 mm/ka、88.3 mm/ka、111.3 mm/ka、149.6 mm/ka和115 mm/ka。通过研究认为,早更新世—晚更新世中期,千河流域区构造运动逐渐加强,晚更新世晚期以后,构造运动逐渐趋缓。河流演化受断裂构造控制,但不同时期构造应力场对千河水系的影响有差别,使千河向不同方向迁移。构造应力场的变化受控于鄂尔多斯地块所处大地构造位置,很可能是青藏高原构造系和西太平洋构造系晚新生代以来在鄂尔多斯西南缘共同作用的结果。

       

      Abstract: The neotectonic movement is active in the southwest margin of Ordos Block, and the development process of river terraces and evolution history of drainage system contain abundant information of neotectonic movement.Five river terraces are asymmetrically distributed on the two banks of Qian River system in the southwest margin of Ordos.Through field investigation and drilling, the terrace structure and development characteristics were clarified.By using electron spin resonance (ESR), optically stimulated luminescence (OSL)and correlation dating of loess strata, the formation age and cutting rate of terrace were analyzed.Combined with regional geological background, the dynamic background of Qian River terrace development and river system changes was also discussed.It is found that T5 to T1 terraces were formed in 1.176 Ma, 0.766 Ma, 0.504 Ma, 0.131 Ma and 0.04 Ma, respectively, with the incision rates of 76.6mm/ka, 88.3mm/ka, 111.3mm/ka, 149.6mm/ka and 115mm/ka, respectively.From the Early Pleistocene to the middle of the Late Pleistocene, the tectonic movement in Qian River basin was gradually strengthened, and after the Late Pleistocene, the tectonic movement was slowly diminished.It is inferred that the incision of the Qian River was driven by different tectonic stress fields, which caused the river to migrate in different directions.The variation of tectonic stress field is probably related to the interaction between the Qinghai-Tibet tectonic system and the western Pacific tectonic system.

       

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