【摘要】 运用近3年来高分辨率地震资料,对南海西北海盆晚中新世以来浊积体的地震相组合和内部特征进行了详细分析,结合浊积体不同时期、不同层段发育特征的逐步演化探讨了海平面变化趋势。认为西北海盆晚中新世到上新世时期浊积体以水道相-天然堤相组合为特征,第四纪浊积体以浊积朵叶体相为主,水道相不发育。频繁发生的水道下切作用及水道相由海向陆的逐渐后退是西北海盆晚中新世以来浊积作用的显著特色,浊积体水道相的这种发育演化特征,表明晚中新世以来海平面总体呈现出上升的变化趋势,而地震层序内部浊积体地震相特征的变化揭示出在晚中新世和上新世期间海平面分别经历至少两次升降旋回,第四纪海平面处于急剧下降后的初期上升阶段。西北海盆晚中新世以来海平面变化的这种趋势,同全球海平面变化周期图晚中新世以来的趋势基本一致。更多还原

【Abstract】 Using the recent high-resolution seismic data of three years,the author analysed the seismic facies combination and inner feature of turbidites in detail and discussed the change of sea level combining turbidites’ characteristics evolution of different epochs and different layers since late Miocene in the northwest sub-basin of the South China Sea(SCS).The turbidites exhibit with channel-levee complex during late Miocene to Pliocene and with lobe facies that channel facies is not distinguished during Quaternary.It is the prominent trait of turbidity action in the northwest sub-basin of the SCS since late Miocene that channels incised continually and retreats from abyssal plain towards the slope.The channel evolving process displays an ascending trend as a whole of sea level since late Miocene.The turbidites seismic facies’ change in the inner sequence reveals the sea level went through respectively not less than two ascending-descending cycles during late Miocene and Pliocene and sea level is early ascending stage after descending quickly during Quaternary.The sea level’s changing trend in the northwest sub-basin of SCS is coincident basically with global Eustacy since late Miocene.更多还原