渭河陇西段第七级阶地年代的确定及其构造意义

Age of the 7th Terrace of Weihe River in Longxi Segment and Its Tectonic Implication

摘要:

昆黄运动是发生在中更新世时期青藏高原及其邻区一次重要的构造抬升事件,河流阶地及地层记录能够较好地反映这次构造事件。渭河陇西段第七级阶地沉积了104.5m厚的黄土,通过对其上覆黄土剖面的古地磁、粒度研究表明,此级阶地形成年代为距今870ka,阶地拔河高度说明自中更新世以来地面至少抬升了205m,其抬升速率约为0.2m/ka。这次构造事件在时间上与昆黄运动相一致,是对青藏高原强烈抬升的响应。

Abstract:

Various evidences of terrace and stratigraphy show that Qinghai-Tibet plateau and its adjacent region experienced an intensive tectonic uplift during the middle Pleistocene,namely the Kunlun-Huanghe Movement.The deepth of 104.5 m loess had been deposited on the 7th terrace of Weihe River in Longxi segment.Through the studing on dating approaches such as palaeomagnetic and grain size,the 7th terrace is estimated to form in about 870 ka before.The height above the river indicates that the uplift amount is at least 205 m from Pleistocene to today,and the move rate is about 0.2 m/ka.The time of this uplift event was same with Kunlun-Huanghe Movement,and was a response to intensive uplift of Qinghai-Tibet plateau.