Molecular Organic Geochemical Record of Paleoenvironmental Changes of Core 17937 in Northern South China Sea Since 40 ka
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摘要: 以分子有机地球化学为手段对南海北部四万年来的古环境古气候研究表明, U37k’-SST表层水温在冰期、间冰期平均范围分别为27℃和24℃, LGM与全新世温差达4.5℃; 以高分子量烷烃所代表的陆源物质输入和长链不饱和酮化合物所代表的海洋初级生产力都呈现冰期高、间冰期低特征, 表明冰期时陆源物质输入的增加和海洋表层生产力的提高; 正构烷烃C31/C27记录了南方大陆的植被由冰期时草本植物占优势向间冰期时木本植物占优势的转变.说明南海在末次冰期以来气候的不稳定性, 和海陆生态系统对气候变化的响应以及分子有机地球化学在古环境古气候研究中的巨大潜力.Abstract: Molecular organic geochemical analysis of Core 17937 in the northern South China Sea has provided useful information on the paleoenvironmental change in the 40 ka and revealed that the average surface temperature of U37k'-SSTs in glacial and interglacial is 27 ℃ and 24 ℃ respectively, resulting in a difference of 4.5 ℃ between Holocene and LGM.The terrestrial input, mainly consisting of high molecular weight alkanes and marine primary productivity, constituting long chain alkenones, both exhibited a high value in glacial and low value in interglacial, which suggests the supply of organic matter from the land is enhanced and the productivity in the ocean during glacial is increased.Alkane ratio of C31/C27 indicated that the predominant plants in South China changed from grass during glacial to tree during interglacial.All the results show the instability of climate since the last glacial in the SCS, and the significant role played by marine and terrestrial ecosystems in climate changes, as well as the potential of molecular organic geochemistry in paleoenvironment and paleoclimate studies.
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Key words:
- biogeochemistry /
- molecular biomarker /
- South China Sea /
- paleoclimate
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图 4 南海北部不同站位的表层水温记录对比(各站位位置见图 1)
Fig. 4. Comparisons of the SST record in northern South China Sea
图 5 17937岩心正构烷烃C31/C27变化曲线与1144站孢粉含量的对比(Sun et al., 2003)
Fig. 5. Comparison of the alkane ratio of C31/C27 in 17937 and pollen percent in 1144
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