杭州湾钱塘江两岸全新世以来的古植被及古气候研究

根据杭州市三个钻孔的孢粉资料对杭州市地区全新世以来的植被和古气候演变进行讨论。这三个钻孔分别位于钱塘江两岸的三盈村(HZ1)、新街三星(HZ2)和下沙镇市场(HZ3),笔者对其进行了孢粉样分析和地层年代学研究。研究结果表明,该区自晚更新世晚期以来的植被演化可以划分为4个阶段:第一阶段为针叶林,气候温凉较湿,海平面低于现今海平面;第二阶段为针叶林或针阔叶混交林,气候温和较湿,海平面接近现今海平面;第三阶段为针阔叶混交林,枫香、榆花粉明显增多,气候温暖较湿,出现高海面;第四阶段为针叶林,气候暖和较湿,海平面接近现今位置。其中第一阶段为末次冰期,第二、三、四阶段为全新世。根据第三阶段的孢粉组合特征、岩性特征以及微体化石可知,全新世中期的气候比较适宜,气候温暖湿润。

A study of vegetation and climate evolution since the Holocene near the banks of the Qiangtang River in Hangzhou Bay

Based on the pollen data and dating results obtained from three drill cores in the region of Hangzhou City,we discuss in this paper the vegetation and climate evolution near Hangzhou City since the Holocene.These three cores are located near the banks of the Qiantang River,at Sanying(HZ1),Sanxing of Xinjie town(HZ2)and Xiasha town(HZ3).The results showed that the vegetation evolution in this area since the Holocene could be divided into four stages.The first stage was dominated by conifers;the climate was mild cool and humid;and the sea level was lower than the present sea level.The second stage was dominated by conifers and mixed forest of conifers and board-leaf trees;the climate was mild and humid;and the sea level approached the present sea level.The third stage was dominated by mixed forest of conifers and board-leaf trees;the pollens of Liquidambar and Ulmus increased dramatically;the climate was warm and humid;and the sea level attained the high stand tract.The fourth stage was dominated by conifers;the climate was warm and humid;and the sea level approached the present level.The first stage was in the last glacial period and the second,third and fourth stages were in the period of the Holocene.According to the characteristics of pollen and spore assemblages,lithology and nanofossils,the climate in the middle Holocene was warm and humid.