舟山群岛峡道底部高程及其冲刷对浙闽沿海泥沙供给的影响

根据舟山群岛峡道地区的钻孔资料，在有孔虫、花粉和沉积特性分析结果的基础上，分析了晚更新世海面变化，探讨了晚更新世末期峡道内的地面高程，进而根据海图量算结果，讨论了舟山群岛峡道底部的泥沙冲淤及其对浙闽沿海泥沙供给的影响。本文认为，晚更新世以来舟山群岛地区发生了三次海进海退，其中晚更新世末期低海面时，舟山群岛峡道高程约位于吴淞基面以下３８ｍ左右，全新世海侵以来，受峡道水动力的作用，除部分峡道内海湾发生淤积外，舟山群岛峡道底部发生了明显的冲刷，其最大冲刷厚度可达８０ｍ左右，为杭州湾乃至整个浙闽沿海提供了大量的泥沙

THE EFFECT OF THE STRAIT CHANNEL BOTTOM ALTITUDE OF ZHOUSHAN ISLANDS AND ITS EROSION ON THE SEDIMENT SUPPLYING IN ZHEJIANG AND FUJIAN COASTAL AREAS

According to analysis of sediment,foraminifera and sporopollen data from the drillings in the channels of Zhoushan Islands area,the sea level changes since Early Pleistocene,the strait channel bottom altitude in Late Pleistocene and the erosion of the channel bottom since Holocene are analyzed,then the effects of the strait channel bottom erosion on the sediment supplying to Zhejiang and Fujian coastal areas are discussed based on measurement and calculation of the modern map.It is pointed out that three transgressions and regressions occurred since Early Pleistocene in Zhoushan Islands area.During the lowest sea level in Late Pleistocene,the bottom altitude of the strait channels in Zhoushan Islands area was about -38m below the Wusong datum.Due to the sea level rise in the Holocene,the strait channel bottom was eroded under the action of the strait channel current except parts of the inner bays in the straits.The mean erosion thickness is about 25m and the largest is nearly 80m in the Jintang Channel,Luotou Channel,Xiashimen Channel and Fodu Channel,which means that the strait bottom erosion has supplied large amount of sediment for the Hangzhou Bay and even for the whole Zhejiang and Fujian coast considering that there be many similar strait channesl along Zhejiang and Fujian coast.