| 渤海古沙漠沉积特征分析 |
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| 引用本文： | 刘振夏,夏东兴.渤海古沙漠沉积特征分析[J].沉积学报,1992,10(2):94-99. |
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| 作者姓名： | 刘振夏 夏东兴 |
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| 作者单位： | 国家海洋局第一海洋研究所, 青岛 |
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| 基金项目： | 国家自然科学基金资助项目 |
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| 摘 要： | 根据世界沙漠的分布特点和沙漠的发育条件,作者认为晚更新世末期渤海气候干冷,雨量稀少,西北风强盛,松散沉积物丰富,具备发育沙漠的条件.文章从以下方面证明渤海古沙漠的存在:(1)渤海约有四分之一区域为残留砂沉积;(2)在全新世盖层下的更新世砂质沉积具有高倾角的前积纹层;(3)渤海东南缘陆地和岛屿有古渤海沙漠衍生黄土分布.综合分析认为末次冰期时,渤海中部和辽东湾古沙漠发育程度好,渤海湾次之,莱州湾未发育沙漠.
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| 关 键 词： | 渤海 古沙漠 |
| 收稿时间： | 1990-07-27 |
Sedimental Characteristics of Ancient Desert in Bohai Sea |
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| Institution: | The First Institute of Oceanography, SOA, Qingdao |
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| Abstract: | During the last glacial stage, the sea level of the world fell down generally with a mean range of about 130 m in East Asia. The continental shelves of Bohai Sea, Yellow Sea and most of East Chian Sea were exposed and turned into land. The influence of southeastern monsoon downhilled, the cold high pressure from Siberia which controlling Asia became stronger and stronger and the area influenced by it was far larger than the present one. When the continental glaciations of mid-high latitude in Europe and America were developed in a large scale, desert and prairie landscapes appeared at the same latitude in Asia because of less precipitation. Bohai Sea was an inland basin located in the centre of Asia during the glacial time and lay about several hundreds of kilometers away from the sea. Because the hills of Liaodong Peninsula, Miao Islands and Shandong Peninsula which are located to the southeast of Bohai Sea resisted the southeastern wind in summer, there was little rainfall there. Under the northwestern blowing it appeared that the topography was reformed and the material was differentiated. Thus, the abundant loose sediments distributed on the sea floor of Bohai Sea supplied enough material for the development of desert. The sandy sediments in Bohai Basin were accumulated to form sand dunes and further to developed into deserts locally. And the silty and clayey materials were blown down to the slope of hills or in the valley located to the southeast of the basin and formed loess there. The 14C dating of the calcareous dolls in the loess suggested that the loess was formed during 12000-25000 B.P. which was the flourish time of the Warm glacial. The dunes consists dominantly of well sorted and rounded medium-fine sand, which is coarse in the northwest and fine in the southeast. At present, the dunes in the central Bohai Sea are covered by the Holocene sediment. The underlying dune sediments have clearly foreset laminae with a high declimation. The dune sediments located in the east and the west of the Bohai Sea are still exposed on the seafloor, and the shape of the dunes was destroyed by the reworking of tidal current and wave. Up to now, about a quarter of Bogai Sea is covered by relict sandy sediments. The lithologic character of the sediments and the subbottom profiler records suggest that the ancient desert mainly distributed in the central Bohai Sea and Liaodong Bay, with relatively less developed in Bohai Bay, and no ancient desert had been formed in Laizhou Bay at the last glaciation. |
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