摘要
通过第四纪沉积物孢粉分析,反映了本区及其周围区域晚第四纪时期的古植被和古气候.晚更新世晚期以松、蒿为主的针阔叶混交林—草原植被,代表第四纪末次冰期盛冰段影响下形成的冷干植物群,气候冷凉干燥,年均气温较现代低6.5—10℃左右,全新世中期为常绿落叶阔叶混交林,气候湿热,年均气温比现代长江下游地区高2—4℃左右.依据气候地层学原则,划分了本区全新世与更新世地层的界线.
This paper studies sporopollen assemblages from 5 cores in the Changjiang River mouth area. In the late Quaternary sedimentary strata, six sporopollen assemblage zones are got, showing the changes of paleovegetation and paleoc-limate in the area and its sitrroundings during late Quaternary. In late period of Late Pleistocene, coniferous and broad-leaf mixed forests-grasslands composed mainly of Pinus and Artemisia represented cold and dry vegetation group which was formed under the influence of the coldest stage in the latest glacial period of Quaternary, although there occur a few Picea and Abies in the sporopollen spectrum, maybe they are scatters from surrounding hills, because there is no virgin forest in the plain region-, at that time, climate in the mouth area was dry and cold, and the mean annual temperature was about 6.5-10 lower than that of today. Evergreen and deciduous and broad-leaf mixed forests and a lot of subtropical fern plants grew flourishingly in middle Holocene, and the climatic environment was a little more preferable to the present's.
Based on the principls of climatic stratigraphy, boundary between Holocene and Pleistocene has been delineated. The Chongming Island, lying on the delta plain, has a Holocene thickness of 55m; in 3lm deep marine region off the ri. ver mouth, the thickness is about 34m. So.it can be calculated that the sedim-entary rate around the Changjiang River delta during Holocene (about 12,000 yrs) is nearly 0.28-0.45 cm/yr.
出处
《海洋地质与第四纪地质》
CAS
CSCD
北大核心
1989年第2期13-26,共14页
Marine Geology & Quaternary Geology
