摘要:
琼东南盆地属于南海北部陆缘拉张盆地,但是由于其不同的发育历史及红河断裂的影响,具有与东部陆缘盆地不同的构造特征。琼东南盆地和珠江口盆地在地壳结构、基底特征等方面存在差异,但是这种差异的原因还不清楚。新生代沉降速率发生多期变化,并存在裂后异常沉降、沉降延迟等现象,其形成机制尚需要进一步研究;平面上,构造具有迁移性,但是对不同地质时期的构造迁移方向仍存在不同的看法。盆地沉降中心和沉积中心经历了由裂陷期和裂后早期的较好重合到裂后晚期的逐步分离,直至完全分离的过程。盆地形成与地幔流的关系,以及红河断裂对盆地裂后沉降迁移的影响,也都是需要进一步确定的工作。鉴于以上各方面存在的问题,对琼东南盆地与南沙的共轭关系、盆地异常沉降、红河断裂及内部构造转换带对构造迁移的影响、以及琼东南盆地与珠江口盆地的比较等方面的研究是下一步工作的重点。
Abstract:
The Qiongdongnan Basin is an extensional one located at the northern margin of the South China Sea. Due to its specific evolutionary history and the impact of the Red River Fault, It has its own structural characteristics quite different from the eastern marginal basins. It is known that the Qiongdongnan Basin is different in crustal structure and basement characteristics with the Pearl River Mouth Basin, but the reasons for the difference remain unclear. Cenozoic sedimentation rate suffered severe changes for several times in the basin, and there existed post-rift anomalous subsidence and subsidence delays. In a plane view, there is horizontal migration of structures, but the direction of migration in different geological periods remains controversial. The subsidence centers fitted well with the depocenters in the rifting period, but became separated since the early stage of post rifting, until the complete separation in the late stage of post rifting. The relationship between Basin formation and mantle flow, and the impact of Red River Fault to post-rift subsidence migration remain in question. According to the data acquired so far, further study is necessary to disclose the relationship between the Qiongdongnan Basin and the Nansha Basin, and to reveal the anomalous subsidence, effects of Red River Fault and the influence of internal structure transition on structural migration. Comparative study of the Qiongdongnan Basin and the Pearl River Mouth Basin is also recommended.
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