| 摘要: |
| 通过分析冲绳海槽北部DOC024柱状样的孢粉记录,重建了该地区7500a BP以来的植被和气候变化历史。该孔自下而上分为4个孢粉组合带:P1带(7500—6600a BP)气候较寒冷湿润;P2(a)带(6600—4900a BP)亚热带植物花粉含量升高,气候变温暖,P2(b)带(4900—3100a BP)温度变化不明显,湿度降低;P3带(3100—1500a BP)温带植物花粉含量升高,热带-亚热带植物花粉含量降低,气温下降;P4带(1500—200a BP)随着蕨类植物的大量繁盛,气温又回升,但从300a BP起,气候又出现下降趋势。文中还对浮游有孔虫δ18O曲线进行了分析,发现它的变化趋势与孢粉组合之间存在着对应性。 |
| 关键词: 冲绳海槽 全新世 孢粉 δ18O曲线 |
| DOI： |
| 分类号: |
| 基金项目:中国科学院知识创新工程重要方向项目,KZCX3-SW-220号;国家自然科学重点基金项目,90411014号 |
附件 |
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| PALYNOLOGICAL RECORD AND ITS PALEOCLIMATE IMPLICATION IN THE NORTHERN OKINAWA TROUGH SINCE 7500a BP |
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CHEN Jin-Xia1,2, LI Tie-Gang1, CAO Qi-Yuan1, CHANG Feng-Ming1
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1.Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071;2.Graduate School,Chinese Academy of Sciences, Beijing,100039
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| Abstract: |
| Okinawa Trough is an important region for paleoceanography study due to its unique geographic location, nevertheless little palynologic work has been done in this area. A 350cm long piston core (DOC024) was sampled at 29°13.93′N/128°08.53′E in June 1992. Its palynology, geochronology (AMS14C) and oxygen isotopic composition (δ18O) of pelagic foraminifer (Neogloboquadrina dutertrei) shell were investigated in this study.
The spore-pollen curves show out a succession with different time intervals that correspond to every subdivision. From bottom to top, the spore-pollen assemblage indicated four major climatic periods. Period 1(7500–6600a BP) was a flourishing period of extratropical vegetation. The spore-pollen assemblage in this period was rich in extratropic vegetation, but indigent in tropical and semi-tropical vegetations. Compositae and Gramineae were very abundant, demonstrating a cold and humid palaeoclimate type in this period. Coniferous and broadleaf were the main forest members in this period. Period 2(a) (6600–4900a BP) is a flourishing period of semitropical species, while those of extratropical ones decreased, indicating temperature increase and the weather was warm and humid. Evergreen broadleaf dominated in this period while herbaceous chrysanthemum and Gramineae lacked. Period 2(b) (4900–3100a BP) was warm but the humidity was decreased comparing to that of Period 2(a). Evergreen broadleaf forest dominated terrestrial plant species and deciduous broadleaved forest predominated in mountainous region. As a whole, no obvious temperature change was noticed but a humidity drop in Period 2(b). Period 3(3100–1500a BP): the pollen content of extratropical species increased and tropical-semitropical ones decreased, reflecting a temperature drop. The most flourishing species were deciduous forest and laurisilvae trees. Period 4(1500–200a BP) is featured by booming fern, and the pollen contents of herbaceous Artemisia peaked while those of Pinus and Quercus dipped, which suggests that the temperature rose again during this period. The climate in Period 4 was warm and dry; evergreen broadleaf forests dominated land vegetation. In addition, the spore-pollen assemblages show a temperature downtrend after 300a BP.
Between 7500 and 6600a BP the δ18O value kept steadily sliding then stabilized between 6600 and 5200a BP. During 5200 to 1900a BP, it was steadily rising again. After 1900a BP, it decreased rapidly and downed to the bottom between 700 and 300a BP, followed by a quick temperature up term.
The feature of the δ18O curve was strongly correlated to the components of spore-pollen assemblage contained in the core samples. |
| Key words: Okinawa Trough, Holocene, Palynology, δ18O data |
