| 摘要: |
| 1989年3-5月在海南岛三亚浅钻取心，用岩石地层学和地质年代学方法研究了海南岛周缘珊瑚礁的基本特征和成礁时代，在此岩心的基础上进一步研究珊瑚礁的ESR谱学特征。结果表明，珊瑚礁Mn2+的ESR信号和古气候变化直接相关，在100%文石基础上归一的Mn2+ESR信号是一种新的灵敏的古气候指示物，其指示的古气候变化和前人发表的研究成果相一致。海南岛三亚珊瑚礁Mn2+ESR信号表明，中国全新世大暖期出现在距今8.6-3.5ka，在距今5.6-3.0ka显示气候波动剧烈，在大约距今5.5ka有短暂降温，之后又明显回升，这些气候变化也和中国哺乳动物化石的分布一致。 |
| 关键词: 古气候变化 珊瑚礁 Mn2+ESR信号 矿物组成 |
| DOI： |
| 分类号: |
| 基金项目:地质行业科学技术发展基金资助项目，9507号 |
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| Mn2+ ESR SIGNALS OF CORAL REEFS AND IT’S IMPLICATIONS FOR PALEOCLIMATE |
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YE Yu-guang,ZHOU Shi-guang,LIU Xin-bo
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Institute of Marine Geology, Ministry of Geology and Mieral Ressources, Qingdao, 266071
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| Abstract: |
| The paleoclimatic change since the Tertiary period was recorded in coral reefs in the South China Sea. It had a direct effect on the changes in Mn2+ ESR signals of coral reefs. The mineral composition, content of Mn and Mn2+ ESR signals of coral reefs in Sanya, Hainan Island, suggest that the normalized Mn2+ ESR signal on the basis of 100% aragonite is a new and sensitive paleoclimatic indicator; the paleoclimatic changes indicated by Mn2+ ESR signals show a very similar changing pattern to the Holocene paleoclimatic fluctuations of China revealed elsewhere. For example, the warmest period from 8.5 to 3.0 ka B. P. corresponds to the most intense ESR signals of Mn2+ in the well Sanya-3 drilled on Hainan Island, and the violently fluctuating climate during 5.6 to 3.0 ka B.P. and a remarkable shon-tem1 lowering of temperature around 5.5 ka B. P. and a rapid rising after that time are also demonstrated by the ESR signals. The ESR signals of Mn2+ are positively correlated to the calcite content but inversely to aragonite content in the coral reef. This can be explained by the fact that the radius of Ca2+ ions in aragonite is different from that in calcite. The mechanism that ESR signals of Mn2+ or Mn content in coral reefs record paleoclimatic changes may be tentatively interpreted as climatic control over the input of run off-carried terrigenous materials into the sea. During warm periods, more terrigenous materials were carried into the sea by runoffs, increasing the concentration of Mn2+ in seawater and thus more Mn2+ being incorporated into lattices of coral reefs. But during cold times, the case is reversed. Although ESR signals of Mn2+ and Mn content in coral reefs can both reflect paleoclimatic changes, the former is more sensitive and reliable than the latter. For example, the sh0rt-tem1 lowing of temperature around 5.5ka B.P. is clear in the ?gure of ESR intensity shown by Mn2+ change with the depth but it cannot be seen in the figure for the Mn content. These paleoclimatic changes are also consistent with the distributions of mammal fossils in China. |
| Key words: Paleoclimatic change, Coral reefs, ESR Signals, Mineral composition |
