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本文介绍了中美合作在南海北部陆缘进行的双船地震（合成排列剖面）工作，讨论了新生代沉积之下的中生代沉积之地震反射特征。在今日陆架新生代沉积之下的中生代沉积之地震反射表现杂乱、低振幅和不连续特性，而在今日上陆坡新生代沉积之下的中生代沉积之地震反射呈现连续、较强振幅和可长距离对比的特征。根据地球物理场特征及区域地质资料，我们指出燕山运动时间广东大陆边缘的构造格架：今日东沙群岛—彭湖列岛—带为火山弧，今日陆架区及广东大陆为弧后区，而今日陆坡区则为弧前区。故今日陆架下的中生代沉积为弧背盆地之沉积，表现为陆相沉积；今日陆坡下的中生代沉积为前弧盆地之沉积，表现为海相沉积。
This paper presents the work of Sino-US cooperation on the double-ship earthquake (synthetic alignment profile) conducted at the northern margin of the South China Sea and discusses the seismic reflection characteristics of the Mesozoic sediments under Cenozoic sedimentation. The seismic reflections of the Mesozoic sediments under Cenozoic sediments in the present Cenozoic show clutter, low amplitude and discontinuities. However, the Mesozoic sedimentary seismic reflection under the Cenozoic sediments of the continental slope today shows continuous, strong amplitude and long distance Contrasting features. According to the geophysical field characteristics and regional geological data, we point out the tectonic framework of the Guangdong margin at the time of the Yanshanian movement: the Dongsha archipelago - Penghu archipelago - today is a volcanic arc, the continental shelf area today and the Guangdong mainland are back arc areas, and today the slope Area for the arc area. Therefore, the Mesozoic sediments under the shelf are the sedimentary facies of arc back basins. The Mesozoic sediments below the slope are the sediments of the forearc basins, which are manifested as marine sediments.