珠江三角洲北部晚第四纪孢粉植物群的古环境意义

PALEOENVIRONMENTAL SIGNIFICANCE OF LATE QUATERNARY POLLEN FLORA IN NORTHERN ZHUJIANG RIVER DELTA

采用孢粉分析的方法对珠江三角洲北部地区多个钻孔进行了古植被和古环境的研究。结果表明，该区晚更新世与全新世的孢粉组合存在明显区别，更新世时期以木本植物为主，而全新世表现为蕨类孢子和草本花粉的大幅度增加。该特征反映了更新世本区为河漫滩洼地沉积为主，局部受海侵影响，而全新世为海湾河口相沉积。根据木本植物花粉不同组分的含量变化以及某些气候敏感属种的出现，可以推论晚更新世亚间冰期的年平均气温比现今低2-4℃左右，盛冰期则低6℃以上，到全新世中期以后形成了与现代相似的明显受季风影响的常绿阔叶林。

The investigated area is located in the north of the Zhujiang River Delta,Guangdong Province. The age of the samples collected from 8 boreholes are from theLate Pleistocene to the Holocene. The result shows that the pollen assemblages areaffected strongly by the changes of sedimentary environment. The Pleistocene pollenassemblages, dominated by arboreal pollen (mainly Castanopsis and Quercus), areconcentrated on the valley flat;whereas the Holocene assemblages,rich in fern sporesand sometimes in herb, are indicative of a river mouth or marine environment.According to the pollen results, the annual mean tomperature is inferred to be 2-4℃lower in the Late Pleistocene and above 6℃ lower in the last glacial maximum thanat present.The development of the south subtropical monsoon evergreen forest begansince 8000 yrs B. P.