| 摘要: |
| 利用热电离质谱方法分析了取自南海不同海域的现代珊瑚和全新世珊瑚样品的Sr、U同位素组成。结果表明，南海珊瑚代表的礁区表层海水87Sr/86Sr比值介于0.708902—0.709401之间，分布相当不均一，而δ234U则主要介于170—180之间，明显高于开放大洋144的结果，反映周边大陆物质输入对南海表层海水组成具有重要影响。 |
| 关键词: Sr-U同位素 造礁珊瑚 南海 |
| DOI：10.11693/hyhz200004014014 |
| 分类号: |
| 基金项目:国家自然科学基金资助项目，49473188号;中国科学院院长基金项目，KJ95-321号;中国科学院南沙综合科学考察项目资助 |
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| STRONTIUM AND URANIUM ISOTOPIC RECORDS FOR THE SURFACE WATER OF THE SOUTH CHINA SEA AND THEIR ENVIRONMENTAL IMPACT |
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WEI Gang-jian1, LI Xian-hua1, NIE Bao-fu2
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1.Guangzhou Institute of Geochemistry, The Chinese Academy of Sciences, Guangzhou510640;2.South China Sea Institute of Oceanology, The Chinese Academy of Sciences, Guangzhou510301
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| Abstract: |
| Coral paleoclimate reconstruction is one of the methods to retain high resolution records of the climatic and environmental change, and it is one of the major subjects of the globe change study. There are a number of successful results in such studies in the ocean, but fewer in the marginal marine environment. However, there are perhaps some differences between the environmental factors, such as the component of the seawater, and those of the ocean. These may probably cause some different response of the coralline records to the climate in the marginal area, compared with that in the ocean. In this case, strontium and uranium isotopic compositions of the seawater are good indicators to mark the special component of the seawater.
In this paper, strontium and uranium isotopic compositions of some modem coral samples and some Holocene corals, which represent the isotopic composition of the seawater when these corals formed, had been analyzed by thermal ionization mass spectrometry method. The results indicate that the Sr and U isotopic compositions of the reef water of the South China differ from those of the ocean at least from 8000a to present. The 87Sr/86Sr ratios of the coral samples from the South China, ranging from 0.708902 to 0.709421 (relative to NBS 987=0.719310), were not as homogeneous as those from the ocean, which range from 0.709200 to 0.709270. δ234U of the modem coral samples and δ234U (T), the initial ratios of the Holocene corals, mostly lie between 170 and 180, which were significantly higher than 144, the homogeneous ratio of the ocean. These observations indicate that the run-off from the continent and nearby islands plays an important role to the isotopic compositions of the surface water of the South China Sea.
The discussion above implied that when reconstructing the paleoclimatic records from the coral of the South China Sea, the special component of the seawater of the South China Sea may not be neglected. |
| Key words: Sr and U isotope, Coral, South China Sea |
