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本次工作对来自南海北部大陆架地区琼东南盆地LS33-1-1井和LS2-1-1井渐新统—上新统的孢粉、藻类进行了系统研究。通过孢粉分析,确定孢粉植物群,恢复古植被,推测古气候,建立了与气候变化趋势相关的孢粉组合序列。结果显示,研究区内渐新统崖城组、陵水组时期的植被类型是热带、亚热带常绿阔叶林及针叶、常绿、落叶阔叶混交林,气候条件较温凉湿润;中新统三亚组时期植被发展为热带、亚热带常绿阔叶林及常绿、落叶阔叶混交林,气候条件暖而湿润;中新统梅山组时期是气候逐渐变化的过渡期;中新统黄流组的植被类型为亚热带针叶阔叶、常绿和落叶阔叶混交林,气候条件温凉略干燥;上新统莺歌海组山地植被中针叶林或针阔叶混交林多有分布,常绿阔叶落叶阔叶林混交林继续扩大,草本植物空前发展,气候趋于凉干。孢粉组合所反映的渐新世—上新世气候变化特征与全球气候变化趋势具有较好的可比性。通过孢粉、藻类资料对沉积环境进行了初步研究,研究区渐新世以近岸浅海的沉积环境为主,为陆架边缘到内陆架区,中新统梅山组及其以上地层应形成于距岸较远海水较深的浅海环境。
This work systematically studied the Oligocene-Pliocene sporopollen and algae in the LS33-1-1 and LS2-1-1 wells in the Qiongdongnan Basin in the northern continental shelf of the South China Sea. The sporopollen assemblages were identified by means of sporopollen analysis, the paleoenvironment was restored and the paleoclimate was estimated. The sequence of sporopollen assemblages related to climate change trend was established. The results show that the vegetation types of the Yacheng Formation and the Lingshui Formation in the study area are tropical and subtropical evergreen broad-leaved forests and coniferous, evergreen and deciduous broad-leaved mixed forests with climatic conditions being cooler and wetter; During the Neogene Sanya Formation, the vegetation developed into a tropical and subtropical evergreen broad-leaved forest and evergreen and deciduous broad-leaved mixed forest with warm and humid climatic conditions. The Miocene Meishan Formation changed gradually during the transitional period. The vegetation types in the flow group are subtropical coniferous and broad-leaved evergreen and deciduous broad-leaved mixed forest with cool and dry climate; the coniferous forest or coniferous-broad-leaved mixed forest in the upper reaches of the Yinggehai Formation , Evergreen broad-leaved deciduous broad-leaved forest mixed forest continues to expand, the unprecedented development of herbs, the climate tends to dry. The Oligocene-Pliocene climate change characteristics reflected by sporopollen assemblages are well comparable with the trend of global climate change. The depositional environment was mainly studied by sporopollen and algae data. The Oligocene in the study area mainly consisted of the sedimentary environment of the coastal shallow sea, which was from the margin of the shelf to the inner shelf. The Meso-Neo-Meishan Formation and its strata should be formed in Far from the shore of the sea water deeper shallow sea environment.