济阳坳陷古近纪页岩形成的孢粉响应特征  

RESPONSE OF SPORE-POLLEN TO THE FORMATION OF PALEOGENE SHALE IN THE JIYANG DEPRESSION

作　　者：贺振建 张存霞 李慧 何青芳 赵慧 

机构地区：[1]中石化股份胜利油田分公司地质科学研究院,东营257015

出　　处：《第四纪研究》2015年第3期660-668,共9页Quaternary Sciences

基　　金：国家重点基础研究发展规划项目（973项目）（批准号：2014CB239102）资助

摘　　要：根据孢粉化石恢复的古气候,济阳坳陷古近系沙河街组沉积时期为亚热带气候,沙河街组四段上亚段、三段下亚段和沙河街组一段沉积时期,气候处于由干旱向潮湿转换时期,藻类勃发,水体仍具一定盐度,是最有利于页岩发育的气候.济阳坳陷沙四上和沙三下页岩中有机质丰度高,有机质类型以腐泥型为主,孢粉化石相对贫乏,孢粉相对密度与有机碳有呈负相关的趋势.区域上,目前钻探页岩厚度较大的井都分布在孢粉相对密度低的地区,且紧邻高值区,据此可确定页岩发育有利区域应该在孢粉相对密度较高的两侧、前方至深湖区.Shales are well developed in the upper part of fourth member（Es4u）, the lower part of third member（Es3l）, and the first member of the Shahejie formation（Es1） of Paleogene age in the Jiyang Depression.Based on the spore-pollen assemblage, the climate was subtropical in the Jiyang Depression when the Shahejie Formation was deposited.In particular, Es4u, Es3l and Es1 were deposited when the climate experienced a transition from dry to wet conditions.So when organic matter began to accumulate in large quantity, the lake still had certain salinity and multiple stratifications that favored shale formation.This suggests that the lake stratification in favor of shale formation in Paleogene was controlled by both temperature and salinity, whereas salinity was also related to climate, pointing at a climate controlling mechanism for the deposition laminated shales.The spore-pollen assemblages were monotonous during the lower part of fourth member of Shahejie Formation.The assemblages were characterized by high content of Ephedripites of drought condition, suggesting an arid climate unfavorable for organic matter accumulation and shale formation.During Es4u-Es3l periods, Ephedripites reduced gradually, while Quercoidites and Taxodiaceaepollenites of wet condition increased, and shales began to develop.During the middle period of the third member of Shahejie Formation, Quercoidites continued to increase and reached its peak during the entire Shahejie Formation sedimentary period, but the lake became fresh and unfavorable for shale formation.Ephedripites showed a small peak during the late period of the second member of Shahejie Formation.The climate gradually turned from dry to wet when entering the Es1 period, Quercoidites dominated the pollen assemblage, and shales began to develop. Because the spores and pollen in lake are mostly derived from terrestrial environment via surface runoff or river transport, abundant pollen are found at places where the lake water is relatively turbulent, a condition unfavorable f

关 键 词：孢粉 相对密度 气候 页岩 古近纪 济阳坳陷 

分 类 号：Q913.84[天文地球—古生物学与地层学] P534.61[生物学—古生物学]