黄河中游响应气候变化和地表相对抬升发育阶地研究

潘保田,胡振波

The study on the terrace development by the middle reaches of Yellow River as a response to the climate change and relative surface uplift

Baotian PAN,Zhenbo HU

图3 黄河阶地序列及上覆黄土横断面图 注：黄河在吴堡形成的阶地序列横断面图(a)。在该区唐县期夷平面限定了晋陕峡谷的谷肩，之下分布7级黄河阶地，除T2和T1为堆积阶地外其余均为基座阶地。每级阶地面上覆厚层黄土，其底部都为一层古土壤直接覆盖在下伏阶地的沙砾石层上。对唐县期夷平面和黄河阶地上覆红黏土与黄土地层划分和测年结果参见文献[25,35]；黄河在南赵发育的阶地序列横断面图(b)。黄河在该区深切峨眉台地，形成6级堆积阶地，其中T6~T4为堆叠的阶地序列（阶地越年轻拔河越高）而T4~T1为正常的阶梯状阶地序列。每级阶地上覆不同厚度的黄土，其黄土-古土壤地层划分和测年结果参见文献[39]。横断面图3(a)与3(b)在黄河中游的位置参见图1和图2

Fig.3 Schematic cross section of the Yellow River terraces and covering loess deposits Note：The cross section of the fluvial terraces created by the Yellow River at Wubao (a). The Yellow River excavates the Tangxian Planation Surface here leading to the formation of the Jinshaan Gorge. A total of 7 fluvial terraces has been generated by the Yellow River along this gorge， which are all strath terraces except the two accumulation terraces of T2 and T1. Their treads are covered by thick loess depositions whose basal paleosols all overlie directly the fluvial sediments. Pedostratigraphic identification and geochronological results of these Red Clay and loess covers have been given in the reference[25,35]；The cross section of the Yellow River terraces occurring at Nanzhao (b). The Yellow River downcuts the Emei Platform here generating a sequence of 6 aggradational terraces which is characterized by the switch from the unusual stacked sequence of terrace T6~T4 to the terrace staircase of T4~T1. The basal paleosols of the loess covers， accumulated on these terrace treads， also superposes directly the underlying fluvial sediments. Their pedostratigraphic identification and geochronological results have been given in the reference[39]. See Fig.1 and Fig.2 for the locations of the two cross sections［Fig.3(a)，3(b)］ with respect to the middle reaches of Yellow River