黄河三角洲滨浅海50m以浅埋藏古河道浅析

Preliminary Analysis of the Ancient Channels Buried Shallower Than 50 Meters in the Coastal and Offshore Areas of the Yellow River Deltaa

黄河三角洲埋藏古河道对工程建设和第四纪环境的研究有重要意义.结合前人的钻孔资料,通过对新老黄河口间近300 km的浅层剖面资料,尤其0～50 m的浅层剖面资料进行分析,发现研究区内古河道属于古黄河水系,断面多呈对称性型,各层位古河道断面在空间上分布具有分区性.河道充填物多为河流溯源堆积,呈发散或上超型反射,工程地质条件差,易造成不均匀沉降、局部塌陷、砂土液化等地质灾害.研究区从约38 kaBP至今共发生3次海退和3次海进,其中1次海退规模较小.

The buried ancient channels in the Yellow River Delta are of great significance for the research of Engineering construction and Quaternary environment. About 300 km shallow stratum profiles are analyzed, particularly those shallower than 50 m. Based on these analyses and combined with the previous drilling data, the buried ancient chan- nels found in the study area belong to the tributaries of the ancient Yellow River sys tern. The sections of the ancient channels are mostly symmetrical and their distributions are divisional in each stratum. Most of the tributaries are filled with retrogressive accu- mulations that have diverging or parallel structures and are poor in engineering geolog ical conditions. These fillings may easily cause geologic hazards such as differential set tlement, carving deformation and liquefaction. Three regressions and three transgres- sions occurred from 38 kaBP to now, of which one regression was small in scale.