摘要
通过对岩芯的观察和测井资料的研究将松辽盆地北部四方台组划分为2个三级层序,8个四级层序,并识别出辫状河和曲流河2种沉积相和8种沉积微相。层序1(SQ1)低水位体系域时期为辫状河相,发育辫状河河床和泛滥平原(河漫滩)两种亚相;水进体系域时期发育曲流河河床和泛滥平原(河漫滩和河漫湖泊)亚相;高水位体系域时期和水退体系域时期发育曲流河河床和泛滥平原(河漫滩、河漫湖泊和决口扇)亚相。结合泥岩样品的地球化学特征即样品的Sr/Cu、Th/U、Rb/Sr和SiO2/Al2O3比值的变化趋势可知SQ1时期气候干热,SQ2时期干旱程度减弱。根据δCe、V/Cr、V/(V+Ni)、Ni/Co和U/Th的变化趋势可知四方台组时期古水体处于氧化还原过渡-氧化环境,SQ1时期水体氧化性更强。古气候、古水体氧化还原性和沉积相之间具有较好的耦合关系:气候干热时,蒸发作用加剧,水体变浅,水体氧化性增强,发育大量河床亚相沉积;气候干旱程度降低时,蒸发作用减缓,水体变深,水体氧化性减弱,以泛滥平原亚相为主。
Based on the observation and analysis of core and well log data,the Sifangtai Formation in the northern part of Songliiao Basin is divided into two third-order sequences and eight fourth-order sequences,with two sedimentary facies and eight sedimentary microfacies identified.The Sequence 1(SQ1)is braided fluvial facies,developing river bed and flood plain sub-facies in the lowstand systems tract period.Meandering river bed and flood plain(overbank and river flood lake)sub-facies occur during the transgressive systems tract period.Meandering river bed and flood plain(overbank,river flood lake and crevasse fan)occur during the highstand systems tract period and the regressive systems tract period.According to the geochemical analysis of mudstone samples,i.e.,the variation trend of Sr/Cu,Th/U,Rb/Sr and Si O2/Al2O3,it is indicated that the climate was hot and dry during the SQ1 period,and was weakened during the SQ2 period.The variation trend ofδCe,V/Cr,V/(V+Ni),Ni/Co and U/Th show that the palaeo-water body during the Sifangtai Formation period was in the redox transition-oxidation environment,and was more oxidized during the SQ1 period.It shows a good coupling relationship between the paleoclimate,the paleowater’s oxidation-reduction and sedimentary facies.When the climate is hot and dry,the evaporation intensifies,the water body becomes shallower and the water body is enhanced in oxidation,resulting in the development of a large number of river bed deposits.When the drought decreases,the evaporation slows down,the water body becomes deeper,and the oxidation becomes weaker,so as to be dominated by flood plain sub-facies.
作者
申林
刘招君
胡菲
李建国
赵丁名
万涛
SHEN Lin;LIU Zhao-jun;HU Fei;LI Jian-guo;ZHAO Ding-ming;WAN Tao(College of Earth Sciences,Jilin University,Changchun 130061,China;Key Laboratory of Oil Shale and Coexistent Energy Minerals of Jilin Province,Changchun 130061,China;Tianjin Center of China Geology Survey,Tianjin 300170,China)
出处
《世界地质》
CAS
2019年第4期988-998,共11页
World Geology
基金
中国地质调查局天津地质调查中心地质调查项目(DD2017128-08(9))
关键词
松辽盆地
四方台组
地球化学
古气候
沉积环境
Songliao Basin
Sifangtai Formation
geochemistry
paleoclimate
sedimentary environment
