淮河上游全新世古洪水沉积学特征及古洪水事件气候背景  

Climatic Implications of the Holocene Flood Events Corded by Sediments in the Upper Huaihe River

作　　者：王兆夺 黄春长 李晓刚 周亚利 庞奖励 查小春 WANG Zhao-duo;HUANG Chun-chang;LI Xiao-gang;ZHOU Ya-li;PANG Jiang-li;ZHA Xiao-chun(Department of Geography,Shaanxi Normal University,Xi＇ an 710119,China;College of Urban,Rural Planning and Architecture,Shangluo Uinversity,Shangluo 726000,China)

机构地区：[1]陕西师范大学地理科学与旅游学院,陕西西安710119 [2]商洛学院城乡规划与建筑工程学院,陕西商洛726000

出　　处：《长江流域资源与环境》2018年第9期2122-2131,共10页Resources and Environment in the Yangtze Basin

基　　金：国家自然科学基金项目(41771110;41701090);中央高校基本科研业务费专项基金(GK.201704013)

摘　　要：通过详细的野外调查,在淮河上游的毛集河口发现了夹有一套淮河古洪水滞流沉积物层的黄土-古土壤剖面。对剖面进行详细观察、分层和取样,并对样品做粒度和化学元素分析,通过OSL测年进行控制点断代,进一步对该流域洪水事件与全球厄尔尼诺现象进行对比。结果认为:自8500a以来,在淮干上游至少发生了6次特大洪水,与厄尔尼诺现象有明显的响应关系。通过对沉积物不同粒级的组分含量对比,认为SWD在粗粒级范围为优势组分,而黄土古土壤在细粒级范围为优势组分,据此可以有效地对古洪水沉积物层加以识别。地球化学分析表明,剖面不同沉积单元上化学元素呈现出鲜明差异,表现为在SWD中SiO_2和Th明显贫化,Fe_2O_3、CaO、MgO、P、V、Sr、Nb富集,Al_2O_3、Na_2O、K_2O、Cr、Zn、Rb在剖面各地层单元中没有表现出明显的区别,通过地球化学元素的富集或贫化特征亦可以很好地识别古洪水滞流沉积物层。通过对古洪水沉积物的识别得到了全新世以来淮河上游特大洪水信息,也一定程度上能够从沉积学角度佐证在该流域特大洪水的发生与全球厄尔尼诺现象密切相关。Through detailed field investigation,palaeoflood slackwater deposits（ SWDs） were identified from loess-palaeosol profiles in the upper reach of Huaihe River Basin. Through detailed observations and sampling,the samples were analyzed based on particle sizes and geochemical elements,and dating in optically stimulated luminescence. These data were further compared with global El Nio events recorded since the beginning of the Holocene. The results show that flooding occurred at least six times during the last 8,500 years in the upper reach of Huaihe River Basin,and those occurrences correlate well with El Nio. By comparing the contents of different grain fractions of sediments,SWD is considered as the dominant component in the range of coarse grain size,whereas the loess-palaeosol is the dominant component in fine grain size range. The difference between the SWDs and loess-palaeosols is apparent. Thus,palaeoflood SWDs can be identified effectively based on particle size characteristics. The geochemical analysis shows that the elements in the sedimentary units of this profile have distinct differences; SiO2 and Th contents are significantly lower and Fe2O3,CaO,MgO,P,V,Sr,and Nb contents are more enriched in the SWDs than in the loess-palaeosols,although Al2O3,Na2O,K2O,Cr,Zn,and Rb contents did not show significant differences between profile layers. Palaeoflood SWDs can also be well identified based on geochemical compositions. We identified the palaeoflood SWDs,and get the palaeofloods data in the upper reach of Huaihe River Basin since the early Holocene. The results also show that these floods are closely related to the global El Nio phenomenon.

关 键 词：淮河上游 全新世 古洪水滞流沉积物 粒度 地球化学 

分 类 号：P512.2[天文地球—地质学] P539.6