宜昌市龙潭河阶地的沉积特征及其环境指示  

Sedimentary Characteristics and Environmental Implications of the Terrces along Longtan River in Yichang

作　　者：张晶[1,2] 柴波[3] 邵长生[4] 张傲[4] ZHANG Jing;CHAI Bo;SHAO Changsheng;ZHANG Ao(Yinshanbeilu Grassland Eco-hydrology National Observation and Research Station,China Institute of Water Resources and Hydropower Research,Beijing 100038,China;Institute of Water Resources for Pastoral Area Ministry of Water Resources,Hohhot 010020,Inner Mongolia,China;School of Envronment Studies,China University of Geosciences(Wuhan),Wuhan 430074,Hubei,China;Wuhan Center of China Geological Survey,Wuhan 430205,Hubei,China)

机构地区：[1]中国水利水电科学研究院,内蒙古阴山北麓草原生态水文国家野外科学观测研究站,北京100038 [2]水利部牧区水利科学研究所,内蒙古呼和浩特010020 [3]中国地质大学(武汉)环境学院,湖北武汉430074 [4]中国地质调查局武汉地质调查中心,湖北武汉430205

出　　处：《西北地质》2022年第4期183-193,共11页Northwestern Geology

基　　金：中国地质调查局项目“沿长江重大工程区地质环境综合调查(中游)”(12120115044101);中国水利水电科学研究院基本科研业务费专项“农牧交错带地下水中溶解性有机质特征及其与硝酸盐耦合作用关系研究”(MK2022J05);草原生态安全协同创新中心重大课题“塔布河流域生态水文特征及生态系统服务评估”(MK0143A032021)联合资助。

摘　　要：河流阶地可以记录河流所属流域的气候变化信息。笔者以宜昌市龙潭河两岸阶地作为研究对象,选取4个典型河流断面横剖面,利用沉积学、环境地球化学等研究方法,对龙潭河阶地的沉积特征及其环境指示开展了野外调查研究。运用熔片法-X射线荧光光谱法(XRF)对阶地沉积物进行物质成分特征分析;选取化学蚀变指数、风化淋溶系数、硅铝率和硅铝铁率4个指标来具体分析龙潭河地区的环境演化过程;并且运用多元统计方法对分析结果进行解释。研究结果显示:宜昌市龙潭河普遍发育四级阶地,东岸形成侵蚀阶地,西岸基座阶地广泛分布;通过分析阶地沉积物化学组分之间的相关关系,可以看出沉积物的性质和物质组成相似,具有富铝铁化和较强化学淋蚀的特征,符合龙潭河地区的温暖湿润化学风化环境。测试结果和多元统计方法的结论都反映出龙潭河流域内第四纪以来气候湿热程度趋于减弱,丰富了宜昌地区河流阶地研究的基础数据,在一定程度上反映了流域内沉积物形成时期的自然地理条件和古气候特点。River terraces can record climate change information of river basins.The terraces of Longtan River in Yichang was selected as the research object and there are four typical river cross-sections,using the methods of sedimentology and environmental geochemical to study the sedimentary characteristics and environmental directives.The terrace sediments was tested by X-ray fluorescence spectrometry(XRF)in order to analysis the characteristics of material composition.Four indexes including CIA,ba,SiO_(2)/Al_(2)O_(3) and SiO_(2)/(Al_(2)O_(3)+Fe_(2)O_(3))were selected to analyze the environmental evolution process in Longtan River,and the analysis results were explained by multivariate statistical method.In addition,using multivariable statistics to make further analyze.The results show that there are four level terraces distributing widely along Longtan River in Yichang.East bank developed erosion terraces,however,pedestal terraces are widely distributed in west bank.According to the correlation among chemical composition,it can be seen that the character and composition of the sediment are similar,which are rich in iron,aluminum,and stronger chemical corrosion.It conforms to warm wet chemical weathering environment in Longtan River.The test reasults and the multivariable statistics'conclusions can reflect that the degree of hot and humid environment in Longtan River tend to be weakened since the quaternary period.In addition,it enrichs the basic data of river terraces in Yichang,which reflects the natural geographical conditions and palaeoclimatic characteristics of sediments in Longtan River in a certain degree.

关 键 词：河流阶地 沉积特征 多元统计 环境演变 

分 类 号：P532[天文地球—古生物学与地层学]