中文摘要：

11DT02孔位于南黄海辐射沙脊群东北部里磕脚沙脊南坡，通过沉积相分析、粒度统计，结合年代地层数据，重建晚更新世以来里磕脚沙脊的长周期环境演化，分析沙脊成因、厘定沙脊发育年代。研究表明：里磕脚沙脊从下至上由潮滩相、硬黏土相、潮滩相和潮流沙脊相组成。潮流沙脊和潮滩由粉砂、细砂和少量黏土组成，两者均成正偏态分布。潮流沙脊和潮滩在概率累积曲线上分别表现为三段式和四段式分布，以跳跃次总体为主，并呈双跳跃特点。研究区晚更新世经历海平面下降发育潮滩环境，到完全暴露形成标志性的“硬黏土”层；全新世初期经历海侵，研究区复又开始潮滩沉积，随后被海水完全淹没，潮流作用渐强，改造下伏潮滩和“硬黏土”，逐渐堆积成高差最大达30m的脊槽地形。

英文摘要：

The South Yellow Sea is a semi-closed shallow epicontinental sea with an average water depth of 46 m. On offshore area, a characteristic tidal radial sand ridge system （TRSRS）, radiating perpendicularly or high angle oblique to the coastline, has developed under a complex tidal current field along the west coast of South Yellow Sea between the north of Yangtze River Delta and the abandoned south of Yellow River Delta. The study area is located in the eastern part of the TRSRS, where the main sandy ridges and associated channels extend in NS direction in outward part and switch to NNE in inner part and finally converge at the apex of Jianggang on land. Core llDT02, located on the southern slope of the Likejiao sandy ridge in the study area, suggests the long term sedimentary environment evolution since the last Pleistocene based on the sedimentary facies, grain- size, and AMS 14C and OSL datings. The results indicate that there are four types of sedimentary facies in the Core llDT02 from bottom to top： tidal flats （lower part）, terrestrial stiff mud, tidal flats （upper part） and tidal sand ridge. The tidal sand ridges and tidal flats are mainly composed of silt and fine sand, which show bed sorting. On the log-probability curves, they display 3 or 4 subpopulations, among which salutation subpopulation constitutes a high proportion. The double salutation population has been found from tidal sand ridge and tidal flat deposits. The long term evolution of the core has shown that the study area was dominated by a broad tidal flat and followed by a subaerial exposure symbolized by ＂stiff mud＂ deposit, which has indicated a sea level decline. At the beginning of the Holocene transgression, the area received the tidal flat again. The tidal sand ridge-channel system has developed after the area was drowned completely due to high stand. The Holocene increasing tidal currents, which was strongly eroded and reworked underlying strata after 7 ka BP, might result in the formation of sand ridges.