兰州大学机构库 >地质科学与矿产资源学院
兰州盆地上新世-更新世过渡期生态环境演变
Alternative TitleEcological Environment Evolution During Pliocene-Pleistocene Transition Period In Lanzhou Basin
陈超勤
Thesis Advisor张成君
2019-05-16
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name学士
Degree Discipline地球化学
Keyword上新世-更新世过渡期 黄土 红黏土 古环境 兰州盆地
Abstract兰州盆地位于黄土高原和西北干旱区过渡带,在新生代晚期发育连续的风成黄土和红粘土序列。对该地区风成黄土和红粘土沉积序列的研究,有助于理解该 地区黄土沉积和红粘土沉积的异同,从而为研究该时期在全球气候背景下对大陆 沉积的控制程度。本文根据野外地层考察(树屏、巉口剖面)、结合实验分析(古 气候替代指标包括:TOC、常量元素、微量元素及常量元素氧化物比值),重建了该地区上新世-更新世过渡期生态环境演变。主要研究结果如下: (1)对树屏和巉口两个剖面进行的TOC含量测定的结果显示,TOC含量在上新世和更新世的变化趋势相同,但是在相同演化阶段,两个地区TOC含量有明显的变化,说明当时这两个剖面所代表的气候变化有小区域性上的差别。(2)巉口剖面的常量元素地球化学分析结果表明,在主要化学元素的组成特征方面上新世红粘土和更新世黄土变现出一致性,但二者在成分含量上有明显 的不同。微量元素分析发现,上新世红粘土、更新世黄土与土壤中的丰度值表现出较大的差异,造成这种差异的原因与载体矿物和本身地球化学行为有关。 (3)对巉口剖面中TOC、CIA、Ki、Na2O/CaO 综合对比分析,巉口剖面上新世晚期处于温暖、湿润的气候条件下中等的化学风化程度,中间存在多次小的气候波动,更新世早期开始出现寒冷、干燥的气候,风化强度较上新世晚期弱, 反映了兰州盆地上新世以来气候逐渐干冷,降水变少的古环境特征。 
Other AbstractLanzhou basin is located in the transition zone between loess plateau and northwest arid region,which developed successional sequence of aeolian loess and red clay in late Cenozoic.The study on the sedimentary sequence of aeolian loess and red clay in this region is helpful to understand the similarities and differences between the sedimentary sequence of loess and red clay in this region, so as to study the degree of control of continental deposition in this period under the global climate background. In this paper, based on the field stratigraphic survey (Shuping, Chankou profile) and combined with the experimental analysis (paleoclimate replacement indexes include: TOC, ratio of major elements, trace elements and oxygen ratio of major elements), the ecological  environment evolution during the transition period from Pliocene to Pleistocene was reconstructed. The main research results are as follows:  (1)The results of determination of TOC contents in Shuping and Chankou profiles show that the contents of TOC have the same trend in Pliocene and Pleistocene, but in the same  evolutionary stage, the TOC contents in the two regions change obviously, indicating that the climate change represented by the two profiles at that time has a small regional difference. (2)The geochemical analysis of major elements in Chankou profile shows that the composition characteristics of major chemical elements are consistent between the Pliocene red clay and the Pleistocene loess. Trace element analysis find that Pliocene red clay, Pleistocene loess and soil abundance values show great differences, which is caused by carrier minerals and their geochemical behavior. (3) Comprehensive comparative analysis of TOC, CIA, Ki and Na2O/CaO in the Chankou profile shows that the chemical weathering degree in the late Pliocene was moderate under warm and humid climatic conditions, with several small climatic fluctuations in the middle. Cold and dry climates began to appear in the early Pleistocene, and the weathering intensity was weaker than that in the late Pliocene. This reflects the palaeoenvironmental characteristics of dry and cold climate 
and less precipitation in Lanzhou Basin since Pliocene. 
Pages40
URL查看原文
Language中文
Document Type学位论文
Identifierhttp://ir.lzu.edu.cn/handle/262010/338440
Collection地质科学与矿产资源学院
Affiliation地质科学与矿产资源学院
First Author AffilicationSchool of Earth Sciences
Recommended Citation
GB/T 7714
陈超勤. 兰州盆地上新世-更新世过渡期生态环境演变[D]. 兰州. 兰州大学,2019.
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