摘要
为恢复延兴盆地城子河组的古环境,对研究区zk6井钻井岩芯系统取样进行地球化学特征分析,结果显示下部含煤岩段Sr/Ba比值为0.20~0.75,平均值为0.41,上部湖泊泥岩段Sr/Ba比值为0.12~0.36,平均值为0.21,反映城子河组整体以淡水沉积为主,且下部含煤岩段较上部湖泊泥岩段盐度高。城子河组所有样品V/(V+Ni)比值为0.72~0.84,Cu/Zn比值为0.10~0.55,Th/U比值为0.28~3.60,δEu值为0.4~0.84,Ce_(anom)值为-0.04~0.09,表明城子河组沉积时期水体为还原环境;下部含煤岩段Sr/Cu比值为5.87~24.12,平均值为11.21,B元素含量为232.60×10^(-6)~721.00×10^(-6),平均值为425.75×10^(-6)。上部湖泊泥岩段Sr/Cu比值为3.56~10.50,平均值为6.00,B元素含量为23.69×10^(-6)~119.00×10^(-6),平均值为78.36×10^(-6),结合Rb/Sr及孢粉化石分析,表明城子河组下部含煤岩段气候干旱,湖泊泥岩段气候湿润,总体上气候自下而上具有由干旱向湿润变化的规律。
This study presents geochemical characteristic analysis of selected samples of the drillcores from zk6 Well,and aims to reconstruct the paleoenvironment of the Chengzihe Formation in Yanxing Basin.It is indicated that Sr/Ba ratios of the lower part of the coal-bearing sections vary from 0.20 to 0.75,with a mean value of0.41,whereas the Sr/Ba ratios of the upper lacustrine mudstone sections vary from 0.12 to 0.36,with a mean value of 0.21.The above research result indicates that Chengzihe Formation were dominated by freshwater sediment,and the lower coal-bearing section shave higher salinity than the upper lacustrine mudstone sections.Moreover,all of the samples from the Chengzihe Formation display V/（V＋Ni）ratios from 0.72 to 0.84,Cu/Zn ratios from0.10 to 0.55,Th/U ratios from 0.28 to 3.60,δEu ratios from 0.4 to 0.84 and Ce（anom）values from-0.04 to 0.09,suggesting that the Chengzihe Formation was formed in reduction environment.The lower part of the coal-bearing rock sections show Sr/Cu ratios from 5.87 to 24.12,with a mean value of 11.21,and B content from 232.60×10^-6to 721.00×10^-6,with a mean value of 425.75×10^-6.The upper lacustrine mudstone sections have Sr/Cu ratios varying from 3.56 to 10.50,with a mean value of 6.00,and have B content varying form 23.69×10^-6to119.00×10^-6,with a mean value of 78.36×10^-6.Combination of Rb/Sr radios with sporopollen analysis results suggests that the lower coal-bearing sections were formed in arid climate,whereas upper lacustrine mudstone sections were formed in humid climate.In conclusion,during the deposition of the Chengzihe Formation the climate changed from arid to humid.
作者
杨绪海
郭巍
张佳音
李文强
侯筱煜
刘帅
YANG Xu-hai;GUO Wei;ZHANG Jia-yin;LI Wen-qiang;HOU Xiao-yu;LIU Shuai(College of Earth Sciences, Jilin University, Changchun 130061, China;Regional Survey of Geology and Mineral Resources, Heilongjiang Province, Harbin 150080, China)
出处
《世界地质》
CAS
2018年第2期491-499,538,共10页
World Geology
基金
中国地质调查局"松辽盆地深部及外围油气基础地质调查"(12120115001601)资助
关键词
延兴盆地
城子河组
古环境恢复
地球化学特征
Yanxing Basin
Chengzihe Formation
paleoenvironment reconstruction
geochemical characteristic
