渤海湾盆地南堡凹陷始新世—渐新世孢粉、藻类与地层对比

EOCENE—OLIGOCENE PALYNOLOGY AND BIOSTRATIGRAPHIC CORRELATION IN THE NANPU SAG,BOHAI BAY BASIN,N.CHINA

南堡凹陷是位于渤海湾盆地黄骅坳陷北部的小型构造单元。为深入研究南堡凹陷古近纪孢粉组合,采集了Gp1和Np288等七口钻井样品。经传统酸、碱处理法获得孢粉化石,并在研究区古近系地层中划分出六个孢粉亚组合:沙三段4亚段的Ephedripites-Taxodiaceaepollenites-Ulmoideipites tricostatus-Pterisisporites属于始新世鲁特期、沙三段1—3亚段的Quercoidites microhenrici-Ulmipollenites minor属于始新世中晚期、沙二段的Ephedripites-Rutaceoipollis-Meliaceoidites与沙一段的Quercoidites-Meliaceoidites属于渐新世早期、东二段与东三段的Ulmipollenites undulosus-Piceaepollenites-Tsugaepollenites与东一段的Juglandaceae-Celtispollenites属于渐新世中晚期。研究区古近纪孢粉组合与黄骅坳陷中北区及滩海地区的孢粉组合可以形成良好对比,并且研究区局部出现的沙三段4、5亚段与渤海湾盆地普遍出现的沙河街组四段上部为同一时期的产物。

Nanpu Sag is a tectonic unit located in the northern Huanghua Depression, Bohai Bay Basin, N. China. We collected samples from 7 wells to research the palynological assemblages of Eocene--Oligocene in the Nanpu Sag. After traditional acid-base treatment of the samples, six palynological sub-assemblages have been identified as fol- lows ： Ephedripites-Taxodiaceaepollenites-Ulmoideipites tricostatus-Pterisisporites from the forth submember of the Shahejie Formation＇s third member belongs to Lutetian; Quercoidites microhenrici-Ulmipollenites minor from 1st-3rd sub-members of the Shahejie Formation＇s third member belongs to the Middle-Late Eocene; Ephedripites-Rutaceoi- pollis-Meliaceoidites from Shahejie Formation＇s second member and Quercoidites-Meliaceoidites from Shahejie For- mation＇s first member belong to the Early-Middle Oligocene; Ulmipollenites undulosus-Piceaepollenites-Tsugaepol- lenites and Juglandaceae-Celtispollenites from Dongying Formation belong to the Middle-Late Oligocene. Eocene-Oli- gocene palynological assemblages in the research area can he well compared with the north-central part and Tanhai area of the Huanghua Depression. And the 4th and 5th sub-members of the Shahejie Formation＇s third member and the upper forth member of the Shahejie Formation which appear widely in the Bohai Bay Basin are regarded as the products in same period of time.