台湾西南海域似海底反射分析

AN ANALYSIS ON BOTTOM SIMULATING REFLECTORS IN SOUTHWEST TAIWAN SEA AREA

台湾西南海域弧陆碰撞及俯冲作用形成增生楔,在增生楔部位地震调查原始炮集数据上可清楚地识别BSR极性及波形特征。通过对该区域地震调查数据处理,获得了常规地震偏移、瞬时振幅及瞬时相位3种属性剖面,三者可清楚地反映BSR特征及分布,瞬时相位剖面还反映了BSR之上弱反射层的结构特征。研究表明,增生楔部位构造沉积明显控制BSR的形成与分布,该区天然气水合物成矿前景良好。

An accretionary sedimentary prism has been formed due to arc-continent collision and plate subduction in the southwest Taiwan sea area. In the accretionary sedimentary prism the waveform and polarity characters of bottom simulating reflectors (BSR) can be seen clearly in the raw seismic survey data of shot gathers. The thickness of the accretionary prism is more than 6000m, with high terrigenous organic debris and high potential for gas hydrate formation. The water depth in this area varies from 900 to 2250m and is suitable for gas hydrate formation considering the temperature and pressure conditions. The conventional migration, instantaneous amplitude and instantaneous phase profiles were obtained through seismic processing. These profiles reflect characters and distributions of BSR clearly. The instantaneous phase profile also exhibits a weak reflection structure above BSR. The results show that BSR is clearly controlled by tectono-sedimentation in the accretionary prism, and this area has bright prospects in gas hydrate.