山东青东凹陷西部古近纪孢粉组合特征及意义

通过对山东青东凹陷西部古近纪地层孢粉研究,共建立4个孢粉组合:Ⅰ.Ephedripites-Inaperturopollenites-Ulmipollenites minor,Ⅱ.Pinaceae-Ulmoideipites tricostatus-Taxodiaceaepollenites,Ⅲ.QuercoiditeshenriciTaxodiaceaepollenites hiatus,Ⅳ.Alnipollenites-Juglanspollenites-Polypodiaceaes porites。根据与渤海湾地区的孢粉资料对比,确定4个组合的时代分别为早始新世晚期—中始新世早期、中始新世早—中期、中始新世中—晚期、中始新世晚期—晚始新世。该区古近纪植被类型由落叶、阔叶和灌木混交林逐步转变为落叶、常绿阔叶和针叶混交林,古气候经历了干热的亚热带气候到湿热的亚热带气候再到亚热带型温暖气候的变化。沙四段上部到沙三段下部沉积时期是研究区烃源岩最为发育时期。

PALEOGENE PALYNOLOGICAL ASSEMBLAGES IN THE WESTERN QINGDONG SAG,SHANDONG PROVINCE AND THEIR SIGNIFICANCE

This paper reports the Paleogene palynological assemblages from the west Qingdong Sag,Shandong Pro-vince.Four assemblages have been recognized,including Ⅰ.Ephedripites-Inaperturopollenites-Ulmipollenites minor,Ⅱ.Pinaceae-Ulmoideipites tricostatus-Taxodiaceaepollenites,Ⅲ.Quercoidites henrici-Taxodiaceaepollenites hiatus,and Ⅳ.Alnipollenites-Juglanspollenites-Polypodiaceaesporites.According to the characteristics of palynological assemblages and comparison with other similar palynological data in the geological history,the assemblageⅠ—IV are suggested to be of the late Early Eocene to the early Middle Eocene,the early to middle Middle Eocene,the middle to late Middle Eocene,and the late Middle Eocene to the Late Eocene,respectively.Sporo-pollen from the sedimentary sequence in the western Qingdong Sag indicates a change from shrub-broadleaf mixed forest to needle-broadleaf mixed forest,with the palaeoclimate evolving from arid to a moist warmer sub-typical environment.The upper ES4 and the lower ES3 are considered to be the main source rocks of hydrocarbon.