渤海现代沉积作用与模式的研究

MODERN SEDIMENTATION MODELS IN THE BOHAI SEA

１９８７－１９９２年，中国科学院海洋研究所与渤海石油公司合作，开展了“渤海石油开发区区域性工程地质调查与评价”的研究。研究区域为水深大于１０ｍ的浅海海域。本文以调查资料为基础，对渤海现代沉积作用与模式进行了全面、深入地探讨，并予以综述。

Analysis of columnar cores and shallow stratigraphic profiles in the Bohai Sea shows that during the low sea level at the end of Pleistocene,the Bohai Sea was in a con-tinental environment and the northeast-southwest part was a 30m deep basin which in-clined gently from northwest to southeast.Sandy and silty clay of fluvial and lacustrine facies and peat and clayey silt of marsh facies were widely distributed in the basin. Exposed regions experienced weathering, ero-sion and eluviation and different-colored or yellowish brown hard clay layers and soil-like layers were formed.With the end of Wurm glaciation,global climate turned warmer and the sea level rose,￣(14)C dating of peat at the lower part of the marine beds gives an age of 8215 ± 300aB,P.-10060±360aB,P.,indicating that sea water began to enter the basin at the time of 8000-10000a B.P.,The Bohai Sea was thus formed. With the coming of the op-timum climate(8000-5000apB.P.),transgression came to its maximum,And then cli-mate turned stable and the sea level slightly dropped, The present situation came into being at about 2000aB.P..Modern sediments in the Bohai Sea belong to terrigenous origin,and the sediment types and distributions are related to compositions of the terrigenous materials and re-ichness,Thickness and sedimentation rates of Holocene marine sediments are large at the Yellow River mouth,but the thickness is also large(up to 6-8m)at the center of the sea due to a huge amount of silt discharge into the sea from the Yellow River,while the less-influenced Liaodong Bay and the east and west coast of the Bohai Sea only have a small thickness(2-3m)。