根据孢粉资料推论长江三角洲地区1200年以来的环境变迁

根据长江三角洲地区全新世９个具代表性钻孔的孢粉分析结果讨论了本区约自１２０００年以来的环境变迁。孢粉序列表明：本区约在距今１２０００年前就已发育了亚热带性质的落叶常绿阔叶林，约在９０００—５０００ａＢ．Ｐ．常绿阔叶林获得大发展。孢粉序列良好地记录了古季风盛衰的历史，表现在：１２０００—１０８００ａＢ．Ｐ．较温湿，东南季风强度加强；１０８００（或１１０００－１００００（或１０３００）ａＢ．Ｐ．偏闵干，东南季风强度减弱，对应于新仙女木期；约自１００００ａ．Ｐ．起，气候好转，气温明显上升，东南季风强度再次增强，约在９０００—５０００ａＢ．Ｐ．温暖湿润，为东南季风强盛期。此外．还讨论了约在距今１１０００年前的海侵，全新世下限和哥德堡事件的年代问题，并确定哥德堡事件的年限为１１０００—１０００ａＢ。Ｐ。

USES OF POLLEN PROFILES TO SHOW THE LAST 12 000 YEARS OF ENVIRONMENTAL CHANGESIN THE YANGTZE RIVER DELTA

This article uses nine pollen profiles from the Yangtze River Delta to determine themajor climate changes in the last 12 000 years in this region. The profiles of pollen assemblages show that subtropical deciduous and evergreen broad-leaved forest already existedabout 12 000 a B.P. and then evergreen broad-leaved forest greatly developed between9 000-5 000 a B.P.in the Yangtze River Delta. These profiles also reflect the changes insummer monsoon strength. Between 12 000 and 10 800 a B. P.,the climate was warm andwet in the Delta when the summer monsoon is strong during this period. During the periodbetween 10 800 (or 11 000)-10 000(or 10 300)a B. P.,the climate turned cool and dry,asreflected by a weaker summer monsoon corresponding to the Younger Dryas event.Thewarmer temperature returned after 10 000 a B.P.in response to the increasing strength ofthe summer monsoon. Between 9 000-5 000 a B.P.,the climate was warm and wet withstrong southeast Asian summer monsoon.The research reported in this paper also ascertained that the last episode of transgression took place around 11 000 a B.P.,and determined that 11 000-10 000a B. P.was themost likely period for a Gothenburg episode.