摘要
榆林西南部靖边地区集中分布的红色砂岩多呈波浪状且层理显著。探究靖边红色砂岩的沉积成因、动力变化,讨论砂岩沉积时期的古气候特征,对于深入了解西北地区红层的沉积环境具有指导意义。从4个“厚层—薄层”剖面中分层采集了120份红色砂岩样品,从粒度组成、粒度参数、端元组分与磁化率等进行分析,得出以下结论:①砂岩中的中砂组分占51.24%,其次为粗砂、细砂与粉砂,厚层砂岩粒径大于薄层;②研究区砂岩非风成沉积物,属淡水河湖相沉积,分离出来的4个端元EM1~EM4指示了总体较强的搬运动力;③砂岩沉积时期气候存在干湿交替变化,但未达到典型干旱气候。剖面中的薄层细粒与磁化率高值指示了相对湿润的气候特征,薄层砂岩沉积时期的降水量高于厚层砂岩。
Red sandstone is widely distributed in the Jingbian region in the southwestern areas of Yulin.The sandstone is predominantly wavy and contains significant sedimentary bedding.It is important to investigate the sedimentary genesis and dynamic changes associated with Jingbian red sandstone and discuss the paleoclimatic characteristics of the sedimentary period of this sandstone formation.In addition,this research has important implications for advancing our understanding of the sedimentary environment of red beds in northwestern China.For stratified sampling,four sections with thick and thin interbeddings were selected,and 120 samples of red sandstone samples were obtained.Based on grain size composition,grain size parameters,end-members,and magnetic susceptibility,the following conclusions were drawn:①The proportion of medium sand in the sandstone was 51.24%,followed by coarse sand,fine sand,and silt.The grain size of the thick sandstone was larger than that of the thin sandstone.②Sandstone in the study area did not constitute aeolian sediment;it belonged to freshwater river lake facies,and the four separated end-members(EM1~EM4)indicated an overall strong transporting force.③During the sedimentary period of the sandstone,the climate alternated between dry and wet conditions,and there was no typical arid climate.The fine grains of the thin layers and high magnetic susceptibility in these sections were indicative of a relatively humid climate,and precipitation during the sedimentary period of the thin-layer sandstone was higher than that of thick-layer sandstone.
作者
王晓宁
岳大鹏
赵景波
WANG Xiaoning;YUE Dapeng;ZHAO Jingbo(School of Geography and Tourism,Shaanxi Normal University,Xi’an 710119,China;State Key Laboratory of Loess and Quaternary Geology,Institute of Earth Environment,Chinese Academy of Sciences,Xi’an 710061,China)
出处
《地球科学进展》
CAS
CSCD
北大核心
2022年第10期1088-1100,共13页
Advances in Earth Science
基金
国家自然科学基金重点项目“第四纪黄土对世界古文明起源的作用研究”(编号:42130507)
黄土与第四纪地质国家重点实验室项目“陕西宜君地区S5古土壤发育时的土壤含水量与水分平衡研究”(编号:SKLLQG2013)资助
关键词
下白垩统砂岩
粒度组成
砂岩成因
沉积环境
靖边县
Lower Cretaceous sandstone
Grain size composition
Sandstone genesis
Sedimentary environment
Jingbian County
作者简介
First author:王晓宁(1996-),女,河南兰考人,博士研究生,主要从事黄土与古气候研究.E-mail:wxn1996@snnu.edu.cn;通信作者:岳大鹏(1964-),男,陕西兴平人,教授,主要从事综合自然地理研究.E-mail:yuedp@snnu.edu.cn
