长江三角洲东缘晚新近纪沉积的孢粉与古环境研究

作者对长江三角洲东缘地区的南汇鹤鸣孔(Hm)、东海1井、高桥G2孔3口钻井晚新近纪地层的孢粉作了研究和对比,划分出了6个孢粉组合带和3个亚带,恢复了本地区植被演替、气候波动的6个阶段:第1阶段为稀疏的针叶、落叶阔叶混交林,反映气候凉冷稍湿;第2阶段为针叶阔叶混交林草地,反映气候温凉略湿;第3阶段为含常绿阔叶树的针叶阔叶混交林,反映气候温和略干;第4阶段为以常绿栎类、栲属、杨梅等为主的常绿阔叶林,反映气候热暖潮湿;第5阶段是以栎、松、禾本科为主的针叶、阔叶混交林,反映气候温暖略干;第6阶段是以落叶栎类、常绿栎类、松为主的落叶阔叶、常绿阔叶、针叶混交林草地,反映气候温暖湿润。这种气候波动与世界性气候变化相一致,为本地区的地层年代划分和对比提供了新的证据,为晚新近纪古植被、古气候、古环境的重建提供了重要的孢粉学资料。

STUDIES ON PALYNOLOGICAL ASSEMBLAGES AND PALEOENVIRONMENT OF LATE QUATERNARY IN THE EAST MARGIN OF THE CHANGJIANG(YANGTZE) RIVER DELTA

This paper is based on the study of pollen and spores from three cores of Hm, Dh1 and G2 at the east margin of Changjiang(Yangtze) River delta. Six palynological assemblages and three sub-assemblages were distinguished. There are six stages about the evolution of vegetation and climate which were reconstructed for the late Quaternary in this area. The mixed sparse forest of conifers and deciduous broad-leave trees, reflecting the cold and a little moist climate (late stage of late Pleistocene). The mixed forest of conifers and broad-leave trees-grassland, reflecting a temperate and little moist climate(sub-arctic period). The mixed forest of conifers and broad-leave trees with a few evergreen broad-leave trees, reflecting a temperate and slightly dry climate(Boreal period). The evergreen broad-leave forest being mainly composed of Quercus(evergreen) and Castanopsis indicating a hot and wet climate(Atlantic period). The mixed forest of conifers and broad-leave trees, indicated by Quercus, Pinus and Gramineae as main element in palynological assemblages, reflecting a warm and little dry climate (Sub-Boreal period). The mixed forest of deciduous broad-leaves, evergreen broad-leaves and conifers, Quercus(deciduous, evergreen) and pines, being the main components, reflecting a warm and moist climate (Sub-Atlantic period). These fluctuations coincide with the global climatic changes. The study provides reliable evidence for the division and comparation of the age of the sediment at this region, also for the biostratigraphy and reconstructions of paleovegetaton, paleoclimate and paleoenvironment in this area during late Quaternary.