黄海中部晚更新世以来的环境变迁

通过黄海中部陆架浅海区QC_2孔岩芯的孢粉分析,证明晚更新世以来此区存在暖—冷—暖三个大的气候期,各期中还间有数个气候亚期。这种气候变化模式可与北欧和加勒比海地区进行对比。其中,距今约120 000—70 000年的第一气候期,该地区地处亚热带,气候温暖湿润,沿岸适合阔叶林生长,此时为全球性海侵时期。距今70 000—10 000年,气候变冷,该地区只海退后被草原植被所覆盖,阔叶林植被基本消失。全新世气温回升,该地区又被海水淹没,阔叶林又回到沿岸地区,但在全新世的晚期,可能受人类活动的影响,阔叶林大面积减少,松和芒萁等次生植被大面积生长,而使其孢粉含量在沉积物中迅速增长。

CLIMATIC CHANGES IN CENTRAL YELLOW SEA SINCE LATE PLEISTOCENE

Based on analysis of the pollen from Core--QC_2 on the continental shelf of central Yellow Sea,three major climatic changes have been recognized from warm to cold to warm conditions since thebeginning of the late Pleistocene, accompanied by minor climatic oscillations. This model of climaticchanges is comparable with that of northern Europe and that of the Caribbean Sea. The conditionsduring 120 000--70 000 yrs. BP were slightly more ameliorative than that of the present. Synchronous with the global seawater encroachment, the warm and humid climate during this firstperiod was suitable for the broadleaf trees to flourish on the adjacent coastal area. The climatebecame cold from 70 000 to 10 000 yrs. BP. After the seawater regression, prairie instead ofbrondleaf tree forests eovered this area. The temperature rebounded in Holocene, and the seawaterinundated this area again,with the resurgence of broadleaf ttee forests on the adjacent coast. In thelate Holocene, however, the area of broadleaf tree forests decreased, giving way to the prosperoussecondary vegetation of Pinus and Dicranopteris which account for the increasing abundance of pollenand spores of the two genera, perhaps because of human influence during the last 3 000 years.