北京地区一万三千年来自然环境的演变

作者在泥炭的普查、勘探工作中,依据地层和泥炭产出特征,于1976年对北京山前平原和山间盆地内全新世古地理环境提出了自己的见解,认为:古-中全新世,区内湖沼发育,分布广泛(图1)。这些湖沼的兴衰变化直接控制了地层的沉积和泥炭的形成。按这一认识,实践中找到了较大型的泥炭矿与新的远景区。

ENVIRONMENTAL CHANGES SINCE 13,000 YEARS AGO IN BEIJING REGION

Based upon the geological investigation of Holocene strata and peat exploration as well as a great deal of data on various kinds of samples obtained by different methods such as chemical analysis of core samples,sporo-pollen analysis,microfossil analysis and radiocarbon dating,etc.,a chronological table of Holocene for Beijing region was established.In light of this table we succeeded in reconstracting the natural landscape for the piedmont plain and inter mountainous basin in Beijing region since the last 13,000 years.In this paper the argument that there occurred mankind’s migration from piedmont to plain with the retreat of lakes and swamps.The Holocene strata in Beijing region can be divided into four groups: the Paleoholocene (13,100-10,100 years ago,Fen Zhuang formation),the Early Holocene (10,100-7,700 years ago,Gao Li Zhang formation),Middle Holocene (7,700-2,100 years ago,Tao Shan formation),and the Late Holocene (from 2,100 years ago to present,Shin Lietun formation).Vegetational development indicates that the early stage of Middle Holocene (7,700-5,600 years ago) was an optimal warm time of the past-glacial period,while 5,600-5,000 years ago the climate became colder than the present time.