| 摘要: |
| 第四纪自然环境的变迁,作为地球环境演変过程的最新一幕,对人类的生存和发展有着重要的意义。近年来,我们对中国东部沿海地区第四纪地质和海岸演化进行了研究,通过沉积物中孢粉和微体古生物等资料,对古气候及植被变化、海陆变迁等自然环境演变问题作了初步分析。宁波地区的研究是其中的一部分。
宁波滨海平原,地处东海之滨、杭州湾南岸,三面环山,一面临海,面积仅850平方公里。本区的第四纪地质调查主要是由浙江省地质局等有关单位进行的。我们利用浙江省地质局第六地质大队提供的钻探岩芯祥品,作了孢粉、微体古生物、软体动物化石分析,并委托中国科学院地球化学研究所C14实验室,作了部分样品的测年。本文总结已获得的资料,提出宁波地区第四纪自然环境演变的初步认识。 |
| 关键词: 第四纪 环境变迁 宁波 |
| DOI： |
| 分类号: |
| 基金项目:中国科学院海洋研究所调查研究报告第823号 |
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| ON QUATERNARY ENVIRONMENTAL CHANGES IN THE NINGBO AREA, ZHEJIANG PROVINCE |
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Meng Guanglan, Han Yousong
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Institute of Oceanology, Academia Sinica
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| Abstract: |
| A preliminary attempt was made to reconstruct climatic conditions in the Ningbo Coastal Plain, Zhejiang Province, based on microfossil analysis of a core drilled on the southern coast of Hangzhou Bay, Bast China Sea. Reaults of analysis show that spores and pollens are rich in the middle and upper parts but scarce in the lower part, and nine sporo-pollen zones are distinguishable from the Upper Pleistocene upwards. Changes in the feature of sporo-pollen assemblages indicate Pleistocene climatic fluctuations and suggest three cool periods, the late Middle Pleistocene, the early and late Late Pleistocene (Q23, Q31 and Q33).During the late Late Pleistocene, which was synchronous with the Dali Glacial Age, the temperature was about 10°C lower than that of today and the weather was not very cold in comparison with that of the innerland, suggesting that this area might have had been in the frontal zone of the glacial borderland. In contrast, the early and the middle Late Pleistocene (Q31 and Q32), and the Holocene were three warmer periods. However, the Holocene can be subdivided into four subperiods. The middle Holocene climate was relatively damper and hotter, with the temperature 1-2°C higher than today. The climatic fluctuations brought about changes in the nature of the vegetation. In the cold weather of the Late Pleistocene,cold-tolerant types such as Abies, Picea and Larix flourished in the conifer-broadleaf forest and forest-grassland. In the ajacent mountain region existed a small tract of Abies beshanzuensis, just like that thriving today in Qingyun County, southern Zhejiang. The middle Holocene found many kinds of evergreens and broadleaf species, such as Quercus glauca and Castanopsis, etc, but less in quantity, indicating that the climate then had been comparatively sultry. The three layers of marine sediments recorded the three transgressions on the Ningbo Plain. The whole area was under the influence of the Holocene transgression,which might have been a little earlier (about 7000-8000 yrs BP)than that happening on the northern part of China coast. The sediments deposited during the two upper Pleistocene transgressions, however, were not so typically marine as the Holocene. The latter two transgressions influenced only the northern and middle parts of the plain. The crustal oscillations of the area investigated are different from those of the Shanghai area and of the coastal plain on the west of the Bohai Sea but are comparable to those happening on the southern coast of the Haizhou Bay. The difference might be attributed to changes in the sea level, in the original topography and in the geomorphological movements,etc. |
| Key words: QUATERNARY ENVIRONMENTAL CHANGES NINGBO |
