武威黄羊河剖面始新世湖相沉积物粒度端元组分及其沉积机制  

Grain size end-member components and sedimentary mechanism of Eocene lacustrine sediments in Huangyang River section of Wuwei Basin

作　　者：方艳秋 王子璇 王艺霖 汪卫国 符超峰[3] 戴霜 胡惠 孔雪 FANG Yanqiu;WANG Zixuan;WANG Yilin;WANG Weiguo;FU Chaofeng;DAI Shuang;HU Hui;KONG Xue(School of Earth Sciences,Lanzhou University,Lanzhou 730000,China;Third Institute of Oceanography,Ministry of Natural Resources,Xiamen 361005,China;School of Earth Science and Resources,Chang’an University,Xi’an 710054,China;Northwest Institute of Nuclear Technology,Xi’an 710024,China)

机构地区：[1]兰州大学地质科学与矿产资源学院,兰州730000 [2]自然资源部第三海洋研究所,厦门361005 [3]长安大学地球科学与资源学院,西安710054 [4]西北核技术研究所,西安710024

出　　处：《地球环境学报》2022年第3期296-307,共12页Journal of Earth Environment

基　　金：第二次青藏高原综合科学考察研究(2019QZKK0704);国家自然科学基金项目(41972213)。

摘　　要：为了解武威地区晚始新世湖相沉积粒度分布特征并提取古气候环境演变信息,本文利用一般化的Weibull分布函数的参数化端元分析方法(EMMA),结合沉积相、谢帕德三角分类图以及中值粒径、标准偏差等粒度参数,对武威地区黄羊河剖面湖相沉积物粒度数据进行分析。结果表明:黄羊河剖面沉积物主要以细粉沙、极细沙和细沙为主。剖面沉积物各粒级组分垂向含量变化曲线分为三个阶段,沉积相依次对应氧化浅湖亚相—滨湖亚相—扩张湖亚相。结合各粒级组分含量垂向变化特征,剖面自下至上一定程度上指示气候由湿润转为干旱化的过程。剖面粒度数据反演得到3个端元(EM),其中EM1可能指示风力高空远距离悬移搬运来的黏土以及区域风力搬运的粉沙组分;EM2可能指示地表径流作用下河流水动力搬运入湖的沉积物;EM3可能代表洪水作用沉积的粗颗粒跃移组分或湖泊经二次扰动再沉积的粗颗粒组分。Background,aim,and scope The Wuwei Basin is located in the eastern Hexi Corridor on the northeastern of the Tibetan Plateau,which is situated at the hinterland of Asia’s inland arid region.The relatively few studies on the paleoclimate in this area have primarily focused on climate change and desert evolution since the Quaternary.Monsoon changes are reconstructed using the Gulang loess sequence to infer chemical weathering intensity,and the Shagou loess has revealed the influence mechanism of western desert evolution.However,studies on paleoclimate changes in the Early Cenozoic as well as reconstructions of the climate in this geologic period in this region are limited.To reconstruct climate change patterns since this period in the Wuwei Basin and decipher the drought process of Asia interior,this contribution employed the grain size distribution characteristics of the Late Eocene lacustrine sediments in the Huangyang River section of the Wuwei Basin and compared it with other aeolian sediments.This paper provides basic data for the interpretation of the drought process in the interior of Asia in the Hexi Corridor and the reconstruction of the paleoenvironment in this area.Materials and methods The grain size distributions of the sediments in the studied succession were measured using a Malvern Mastersizer 2000 laser instrument,the grain size data of the Huangyang River profile was imported using AnalySize software running in Matlab,and grain size components were separated using the parametric endmember analysis method to obtain potential paleoclimate information.Results Results show that the sediments in the Huangyang River section are primarily composed of fine silt sands,very fine sands,and fine sands.Sedimentary facies within this profile vary from bottom to top,and three grain size end-members are present,which represent different origins respectively.Discussion The grain size of EM1 primarily ranges from 1.0—40.0μm,and the frequency curve of EM1 is similar to the frequency curve of the collected aeolia

关 键 词：湖相沉积 粒度分布 端元分析 沉积机制 黄羊河剖面 

分 类 号：P512.2[天文地球—地质学] P532