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    滹沱河中游河道带150 ka以来沉积环境演化及其对气候变化的响应

    Sedimentary environment evolution of the paleochannel in the middle reaches of Hutuo River since 150, 000 years and its response of climate change

    • 摘要: 古河道记载了地质历史时期区域水系结构和沉积环境的演变信息,对复原古环境、水系变迁规律等具有重要理论意义。依托滹沱河冲洪积扇扇中古河道带上的一个第四纪钻孔(L2),基于详细的岩性特征、粒度参数和光释光年龄数据,文章深入分析了古河道发育的期次和时段,探讨了滹沱河中游古河道带150 ka以来的沉积环境演变过程及其对气候变化的响应。结果表明:研究区150 ka以来的沉积环境演化主要表现为三期古河道发育期与两期河流稳定期的交替,与深海氧同位素阶段及其指示的气候冷暖变化有很好的对应关系。其中三期古河道发育期分别对应于深海氧同位素第2、4、6阶段及其指示的气候冷期,两期河流稳定期对应于深海氧同位素第3、5阶段及其指示的气候暖期。第三期古河道(118~151 ka)是由距今150 ka的共和运动引起的构造抬升与倒数第二次冰期冷干气候的共同作用形成;第二期古河道(36~76 ka)是区域间歇性构造抬升与气候变化共同作用的结果;而第一期古河道(5~26 ka)则是末次盛冰期气候变化的产物。

       

      Abstract: Palaeochannel records the evolution information of regional drainage system structure and sedimentary environment in geological history, which is of great theoretical significance to the restoration of palaeoenvironment and the evolution law of drainage system. Based on a Quaternary borehole (L2) in the paleochannel of the alluvial and diluvial fan of Hutuo River, detailed lithological characteristics, grain size parameters and optical ages, the development periods and sedimentary environment evolution of the paleochannel in the middle of Hutuo River since 150, 000 years and its response of climate change was discussed. The results show that the sedimentary environment evolution of the study area is mainly composed of three paleochannel development periods and two river stabilization periods since 150, 000 years. It has a good correspondence with the deep-sea oxygen isotope stage and the climate change indicated. The three periods of paleochannel development correspond to the second, fourth and sixth stages of the deep-sea oxygen isotopes, and the cold climate respectively. Two river stabilization periods corresponds to the third and fifth stages of the deep-sea oxygen isotopes, and the warm climate respectively. The third paleochannel (about 151~118 ka) was formed by the combination of tectonic uplift caused by the republican movement 150 thousand years ago and the cold-dry climate during the penultimate glaciation. The second palaeochannel (about 76~36 ka) is the result of intermittent regional tectonic uplift and climate change. And the first palaeochannel (about 26~5 ka) was the result of climate change during the last glacial maximum.

       

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