渭河宝鸡峡全新世古洪水事件研究

Palaeoflood events in the Baojixia Gorges of the Weihe River

通过对渭河流域的调查,在渭河上游宝鸡峡谷发现了含有典型古洪水滞流沉积层的全新世黄土古土壤剖面.对该剖面进行磁化率、烧失量、碳酸钙、粒度等指标的分析测定和论证,明确了古洪水滞流沉积物的基本特点,揭示出全新世古洪水事件的沉积学记录.根据这组古洪水沉积层出现的地层位置和磁化率等气候变化指标,通过与渭河流域诸多剖面的对比,并且结合该剖面所含的龙山文化层和西周文化层考古学断代,确定渭河宝鸡峡谷全新世特大洪水事件发生在3 200~3 000 a B.P..

By field investigation in the upper reaches of the Weihe River,the Holocene loess-soil profile containing the typical palaeoflood slackwater deposit was found in the Baojixia Gorges.Analytical results of magnetic susceptibility,loss-on-ignition,CaCO3 content and grain-size distribution indicated that these palaeoflood deposits are different from the soil and the loess,and consists of fine silt and clay.According to this group of palaeoflood slackwater deposit location and climate change indicators such as magnetic susceptibility,through a number of profile comparison in Weihe River basin,and human remains of the Longshan Culture and the West Zhou dynasty,the palaeoflood events were dated to 3 200～3 000 a B.P..