摘要
通过对黄河中游进行古洪水沉积学研究和水文学研究,为超长尺度水文学提供数据基础。对黄河中游晋陕峡谷段进行详细的考察,在黄河窟野河口右侧柳林滩附近发现3层全新世古洪水滞流沉积物（SWD）。光释光（OSL）测年结果表明,这一期3次古洪水事件分别发生在11 800~11 000aB.P.,10 800~10 200a B.P.,10 600~9 600aB.P.。通过对样品进行磁化率、烧失量、粒度成分、化学元素和扫描电镜的试验分析,确定其为河流悬移质泥沙在高水位滞流环境下的产物,是典型的古洪水滞流沉积物。其中,古洪水SWD的磁化率和烧失量较古土壤低,说明其是新鲜的滞流沉积物,未受到风化成壤作用的影响。3层古洪水SWD的自然分布频率曲线都呈现单峰,峰态尖锐,为极正偏态,说明其分选性好。扫描电镜的分析表明,3层SWD属于河流沙,偏关县L0属于典型的黄土—风积粉砂。不同层次的沉积物记录了不同期次的古洪水事件,反映出其水动力大小的不同或物质来源的差异。结合粒度分析和化学元素的结果,确定古洪水SWD2、SWD3与现代洪水SWD均为细沙质粉沙,化学成分相同,表明是黄河主流大洪水悬移质沉积形成。古洪水SWD1为中沙,与SWD2、SWD3在常量元素和重金属元素含量上有显著差异,而与前人在毛乌素沙漠地区所进行的粒度和元素分析结果接近,说明本层古洪水SWD是支流窟野河流域暴雨洪水从毛乌素沙漠地区侵蚀搬运而沉积下来的物质。该研究成果为今后准确鉴别古洪水SWD及来源判断提供参考借鉴。
The data generated from palaeoflood hydrology will facilitate an appropriate assessment of these flood events and the regional response of the hydrological system to global climatic change at a long time scale.Palaeoflood slackwater deposit（SWD）is a major evidence used for inference about hydrological parameters of the past flood events.Field investigation was carried out in Shaanxi province along the middle reaches of the Yellow River.A set of 3layers of palaeoflood SWD at the Liulintan（LLT）site was sampled and investigated in detail.According to the OSL dating results,3palaeoflood events respectively were determined to be in 11 800 to 11 000 aB.P.,10 800 to 10 200 aB.P.,and 10 600 to 9 600 aB.P.Analysis of the magnetic susceptibility,ignition loss,grain-size distribution,chemical element and scanning electron microscope results indicated that these SWD were generated through the deposition of suspended sediments under high water level hesitation environment,belonging to the typical palaeoflood slackwater deposit.The magnetic susceptibility and losson-ignition of the slackwater deposits were low because they were newly deposited and unaffected by weathering and pedogenesis.The shapes of particle-size distribution curves of the 3layers of slackwater deposits were high and thin（single peak）,showing the good sorting characteristics of SWD.According to the analysis of the scanning electron microscope,3layers of SWD belonged to river sand and the L0 of Pianguan county belonged to typical loess-aeolian silt sand.Different levels of sediment recorded the different palaeoflood events,which reflected the differences in hydrodynamic size and material sources.The results of grain size and chemical element analysis indicated that 3layers of SWD belonged to fine silt sand and were sourced from the suspended sediment of floodwater of main stream of Yellow River.Among these sediments,SWD1 wasdifferent from others in the contents of major elements and heavy metal elements,but was similar with the sediment matter for
出处
《水土保持学报》
CSCD
北大核心
2016年第2期136-142,共7页
Journal of Soil and Water Conservation
基金
国家自然科学基金项目"黄河晋陕峡谷全新世古洪水事件及其与季风气候变化关系研究"(41471071)
关键词
古洪水
滞流沉积物
全新世
黄河中游
palaeoflood
slackwater deposit
Holocene
middle reaches of the Yellow River
