南海北部海底微地貌特征与近代变化

MICRO-GEOMORPHIC FEATURES AND THEIR DYNAMIC CHANGE IN NORTHERN SOUTH CHINA SEA

根据大量测深和旁侧声纳资料,对南海北部海底微地貌特征进行了分析,并探讨了近代微地貌动态变化。滨海地貌主要有河口港湾、水下浅滩、水下岸坡、水下三角洲、潮流三角洲海底沙波、潮流沙脊、海釜等;内陆架地貌主要有陆架堆积平原、水下阶地、古海岸线、古河道、小丘和坑洼群等;外陆架地貌主要有陆架平原、古浅滩、古三角洲、浅槽、沙波、沙丘、埋藏古河道海底滑坡等等残留地貌滨海地区水动力作用强,加上人为因素,地貌形态变化较大,内陆架和外陆架水动力作用较弱。

Based on a large amount of bathymetric and side-scan data, the micro-geomorphic features and their recent change were discussed in the present paper. There exist the different geomorphic types including the branching bay, submarine shoal, subfluvial bank, subaquatic delta, tidal current delta, tidal sand ridge, sand wave and caldron in the littoral zone. In the inner shelf, the main geomorphic types have the accumulational plain, shoreface terrace, an- cient costal line, ancient stream channel, mamelon and pit-and-pots. However the main geo- morphic types in the outer shelf include shelf plain, ancient shoal, ancient delta, slack, sand wave, sand dune, buried ancient stream channel and submarine slumping. The geomorphic shapes changed greatly because of the strong hydrodynamic action and the anthropic factor in the littoral zone, whereas the geomorphic shapes are relatively stable because of the weak hy- drodynamic action in the inner and outer shelf.