| 五千年来南海海平面变化的研究 |
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| 引用本文： | 聂宝符.五千年来南海海平面变化的研究[J].第四纪研究,1996,16(1):80-87. |
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| 作者姓名： | 聂宝符 |
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| 作者单位： | 中国科学院南海海洋研究所 |
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| 基金项目： | 国家自然科学基金,南沙综合考察资助 |
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| 摘 要： | 大型块状滨珊瑚的生长上限充其量只能达到大潮低潮面,礁坪面成为古高海面的极好标志。多数学者认为,５０００ａＢ．Ｐ．以来南海周边曾有３—６ｍ的高海面。但南海曾否有古高海面有着两种截然相反的意见。作者对南沙群岛、西沙群岛、海南岛、雷州半岛和台湾恒春半岛珊瑚礁的考察,实测礁顶面的高程,钻取岩芯样品做(１４)Ｃ测年,并收集大量古高海面礁的资料,进一步证实了南海同它的周边情况一样,确实出现过至少比现今高２—３ｍ的高海面。
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| 关 键 词： | 高海面 珊瑚礁 南海 |
SEA-LEVEL CHANGES OF THE SOUTH CHINA SEA IN THE PAST 5000 YEARS |
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| Institution: | South China Sea Institute of Oceanology, Chinese Academy of Sciences |
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| Abstract: | Many studies of sea-level changes in the littoral area of the South China Sea during the Holocene have been carried out in recent years and it is concluded that the sea-level in the middle Holocene was about 3-6m higher than that today.However, several authors have argued against this opinion. The author holds that the key aspect in sea-level change studies is the selection of reliable indicators. The reef-building corals, especially the large massive of Porttes, grow up and also grow to the surrounding area in a certain water depth and normal condition. The growing top limitation is the low spring tide, to which the top corals will die and the others will grow continuously to the enclosing area under the sea water. The factor controlled test made by the earlier workers indicates that the corals will die in one hour under dry condition. So the top level of the dead coral reef is no doubt to be the initial record for the high sea-level. The time when the top of the coral dies is exactly the time of the high sea-level.Many pieces of evidence for high sea-level have been found in the South China Sea based on the- coral reef investigations in a long period. The reef flats of Banyue, Xiane, Jianzhang, Niuchelun, Men, Huanglu, Nantong, Banlu,Nanping and Yongshu reefs in Nansha Islands are all or partly emerged during the low spring tide. The reef flats in Xisha Islands, Dongsha Islands, Hainan Island and Leizhou Peninsula are also emerged wholly or partly in the low spring tide just as that of the Nansha Islands. Each emerged reef flat is composed of an original reef and a thin upper layer of debris of Acropora and other organism. This combination of deposits is called "Original reef flat deposits". They were the results of sea-level lowering from reef flats and patch reefs in lagoons in many regions of the South China Sea. The height from the surface of the reef flats to the level of the low spring tide was measured. In Nansha islands, the height is in range of 30-40cm in the reef flats of Yongshu reef and other 7 reefs (atolls). The difference is 90 - 130cm in the reef front and 160 - 266 cm in the intermediate and rear of the reef flats in Dengloujiao and Shuiweicun of Leizhou Peninsula.The high sea-level reef during the last several thousand years was all located in the nearby high tide level in the Hengchun Peninsula of Taiwan Island. The above measured data indicate that the height of the surface of the lagoonal patch reefs are 20 - 40cm higher than that of reef flats, which reveals that the erosion in reef flat. must be stronger than that of lagooal patch reef.The periods of high sea-levels, based on the 14C age-measurements, are 200-5000a B.P. in Huayang and Yongshu reefs in Nansha Islands, 4300-3600aB.P.in Xisha Islands, 6000-3000aB.P. in Hainan Island and approximately 7000 aB.P. in Leizhou Peninsula, suggesting that the high sea-level in the South China Sea occurred at about 5000aB.P.The difference from the surface of the coral reef to the growing top limitation of the living coral or the present low spring tide should be the height indicating the sea-level higher than that of the present. However, the South China Sea is a monsoon prevailing region, especially the Southwest monsoon in the summer time and tropical storms with the recorded wave height of 7m in Xisha Islands, of which the high waves carry a lot of sands, gravels, and coral fragments with the strongly erosion activities of rolling friction forward and backward in the surface of the top reef which influence the survival of the corals. Actually the corals will die before reaching the low spring tide when they grow up. Only small living Porttes were found under 1. 5m of the level of the low spring tide and the large normal growing Porttes were discovered under 3-4m of the level of the low spring tide in Wufang reef of Nansha Islands. The large normal growing Porites were found under 4m of the level of the low spring tide in reef front of Yongxing Island of Xisha Islands and Xiaodonghai of Hainan Island. Therefore, the actually growing top limitation of Por |
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