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基于内蒙古河套盆地山前兵房沟湖相层剖面沉积物的粒度记录,结合~(14)C和光释光年代学测试,对比分析沉积物粒度敏感粒级及频率曲线特征,反演了河套古大湖150ka以来的湖泊水位变化。研究结果表明,河套古大湖水位变化经历了4个阶段:(1)初始形成阶段(150~130ka),河套古大湖处于浅湖环境,沉积物粒度由粗变细,湖泊处于水位上升期;(2)发展阶段(130~54ka),早期湖水面较高,处于深水环境,晚期沉积物粒度逐渐变粗,湖泊水位有所下降;(3)萎缩阶段(54~18ka),湖泊水位快速下降,细粒沉积物含量减少,中粗粒沉积物含量增大,湖泊水位迅速下降;(4)消亡阶段(18ka至今),由于山前活动断裂影响,阴山快速隆升,湖泊急剧萎缩,湖相层顶部被山间冲洪积物覆盖。控制河套古大湖湖泊水位变化的主要因素是构造运动和气候环境突变。
Based on the grain-size records of the sediments in the Bingfanggou-Lacustrine layer of the Piedmont Gully, in the Hetao Basin, Inner Mongolia, combined with ~ (14) C and photoluminescence dating, the characteristics of grain size and frequency curve were compared and analyzed. Changes in lake water level since the 150th century. The results show that the water level of the ancient Great Lake in Hetao experienced four stages: (1) the initial formation stage (150 ~ 130 ka), the ancient lake in Hetao was in a shallow lake environment, the grain size of the sediment changed from coarse to thin and the lake was at the rising stage of water level; 2) In the developmental stage (130-54 ka), the water level in early stage is relatively high, and in deep-water environment, the grain size of late sediment becomes thicker and the water level in lakes decreases. (3) During the shrinking stage (54-18 ka) (4) the extinction phase (18 ka till now), due to the influence of foreland active faults, the Yinshan rapid uplift, the lake shrinks sharply, and the lacustrine layer The top is covered by alluvial sediments in the mountains. The major factors that control the water level changes in the Hetao ancient lakes and lakes are the tectonic movements and the abrupt changes in climate environment.