汶东凹陷古近纪地层特征及沉积环境分析

Analysis on Strata Characteristics and Sedimentary Enviro nment of Paleogene System in Wendong Depression

摘要:

汶东凹陷古近系分为古新世固城组和始新世大汶口组。大汶口组又分上、中、下3段,相应有3个化石组合带。从地震反射看,该凹陷内自下而上呈5组反射波特征。以古近纪地层特征为基础,结合构造演化分析认为:固城组为干旱气候条件下的山麓洪积相沉积,大汶口组下段为干旱条件下浅湖相沉积,大汶口组中段为逐渐湿润条件下的氧化—还原湖相沉积,大汶口组上段为潮湿气候条件下的还原湖相沉积。

Abstract:

Paleogene system in Wendong depression can be divide d into Palaeocene Gucheng formation and Eocene Dawenkou formation. Dawenkou format ion can be divided into upper, middle and lower parts, and has three fossil comb ination belts correspondently. Seeing form earthquake reflection, this depressio n have five groups of reflection wave characteristics from lower to upper part. Regarding Paleogene system strata characteristics as basis and combing with anal ysis of structural evolution, it is regarded that Gucheng formation is torrentia l facies sedimentary under dry condition, lower part of Dawenkou formation is sh allow lake facies sedimentary under dry condition, middle part of Dawenkou forma tion is Oxidition-reduction lake facies sedimentary under slowly wet condition, and upper part of Dawenkou formation is reduction lake facies sedimentary under wet condition.