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| 海南三亚鹿回头半岛珊瑚礁和连岛坝的发育 | |
| 引用本文： | 赵希涛,陈欣树,郑范,孙绍先,陈俊仁.海南三亚鹿回头半岛珊瑚礁和连岛坝的发育[J].第四纪研究,1996,16(1):48-58. |
| 作者姓名： | 赵希涛 陈欣树 郑范 孙绍先 陈俊仁 |
| 作者单位： | 中国科学院地质研究所，中国科学院南海海洋研究所，地质矿产部广州海洋地质调查局地质研究所 |
| 摘 要： | 海南岛南端三亚市鹿回头半岛由鹿回头岭陆连岛、椰庄连岛坝和南边岭－火岭三部分组成。该地珊瑚岸礁发育良好。为揭示珊瑚礁发育历史，作者在椰庄连岛坝上打了一口深达２６．５ｍ穿透第四纪松散沉积物的钻孔，并对钻孔岩芯进行了微体古生物和孢粉分析以及１４Ｃ和热释光年龄测定，从而区分出晚更新世和全新世两套海相地层，其间隔以晚更新世末期的陆相沉积。研究表明，本区的珊瑚礁主要建造于标高－１３—－９ｍ左右的松散沉积物基底上，开始出现于８５００—８０００ａＢ．Ｐ，繁盛于６３００—４８００ａＢ．Ｐ．的全新世最高海面时期，当时海面高于现今２—３ｍ或更多。近五千年来，随海面波动和下降，珊瑚礁发育渐趋衰退，连岛坝随之开始形成。 |
| 关 键 词： | 晚第四纪 珊瑚礁 连岛坝 海面变化 |
DEVELOPMENT OF THE CORAL REEFS AND TOMBOLO OF LUHUITOU PENINSULA, SANYA CITY,HAINAN PROVINCE |
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| Institution: | 1. Institute of Geology, Chinese Academy of Sciences; 2. South China Sea Istitute of Oceanology, Chinese Academy of Sciences; 3.Institute of Geology, Guangzhou Marine Geological Servey, Ministry of Geolog and Mineral Resources |
| Abstract: | Luhuitou Peninsula situated at the southern end of Hainan Island is one of the areas where the Holocene fringing reefs are the most developed in China.It consists of three parts: the Luhuitouling tombolo island, the Yezhuang tombolo and the Nanbianling-Huoling hills.Luhuitouling is a precipitous hilly area formed by Yanshanian granite and silicon shale of Cambrian Damao Formation.The Yezhuang tombolo resembles a bee-waist, with a length of 1.2 to 2.6km in the northeast direction, and a width of 1.3 to 2.4km in the northwest di rection.The width of the "bee-waist" is only 1km, 2 to 5m above the sea level.There are 2 to 3 lines of bars or spits formed by coralline and shellish sand and gravels or sandstone and conglomerates (alternatively named secondary reefs). Between the bars or spits on both sides, there are dried lagoon depressions where exist a few coralline and shellish debries and coral reef limestones (alternatively named raised coral reefs) which is 1.8m over the mean high tide level. A relatively broad primary reef flats exist in the intertidal zone on both sides of the YeZhuang tombolo, which connect the raised coral reefs that project from inner tombolo or are covered by sediments.Nanbianling and Huoling are composed of sandstones and conglomerates of Devonian Shanpo Formation and silicone shale of Cambrian Damao Formation, respectively. There are also primary reef flats in the intertidal zones along the northern coasts ot the hills. The fringing reefs along the northwestern coast of Luhuitou Peninsula are the most developed. The maximal breadth is over 500m.The southeastern coast comes next, which covers a breadth of 200 to 300m. The southwestern coast of Xiaodonghai is more developed than the northeastern coast.In order to suggest the stratigraphy, development of the coral reefs, the coastal evolution and the sea level changes in the Quaternary, the authors drilled a hole of 26.5m deep, the Luhuitou L1 hole, which had penetrated the whole Quaternary strata. The L1 hole is located at the southwest part of the dried lagoon in the Yezhuang tombolo (109°28'38' E, 18°12' 32" N ). The surface of the hole mouth is 1. 12m above the sea level. The strata and sediments, 14C and thermoluminescent datings, as well as the foraminiferal and sporo-pollen assemblages of the L1 core are shown in Fig. 1.On the basis of the data from the L1 core and other researches, the following conclusions can be obtained:1. The Yezhuang tmbolo consists of two marine layers, the middle-late Late Pleistocene and the Holocene, and continental layer of the end of Late Pleistocene in between.2. The Holocene coral reefs were mainly constructed on the basement of the Late Pleistocene continental or marine sediments.3. Development of the Holocene coral reefs in Luhuitou Peninsula can be divided into the following stages :The Ximao stage (8500- 8000aB.P.), a developing stage of the coral reefs in this area, when the sea level had raised to -13 to -9m or higher, the sea water had merged the Yezhuang area and seperated Luhuitouling from the mainbody of Hainan Island.The Luhuitou stage (6300-4800aB.P.), a flourishing stage of the coral reefs in this area, when the sea level was 2-3m or more higher than that of the present.The reef corals flourished in the warm sea water along the coasts of Sanya Harbour, Yulin Harbour, Luhuitouling island, Nanbianling and Huoling hills,forming an unified broad reef flat. The length and width of reef flat could be over 2km.Since about 5000aB. P., the sea regressed on the whole. With the general trend of regression, there were still two or more oscillations. At the Yezhuang stage (4400-4000aB.P.) and the Dongmao stage (3800-3600aB.P.),development of the coral reefs in this area entered a degenerative stage, whereas bars and spits started to be deposited, and the Yezhuang lagoon was formed.This lagoon lasted untill to 2500-1300aB. P. After then the Yezhuang lagoon disappeared and the Yezhuang tombolo came out. At the same time, the Luhuitouling tombolo island connected with the mainland of Hainan Island. |
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