南海南部海域中中新世(T3界面)构造变革界面地震反射特征及构造含义

南海南部海域油气资源丰富,由于盆地沉积厚度大、沉积相横向变化快和构造演化复杂等原因,致使该海域新生代地层的划分方案差异大,地层时代的认识也存在较大分歧,这极大地制约了对盆地油气资源评价的正确认识.本文在总结国内外不同分层方案基础上,通过收集国外在南海南部深水区两口关键钻井的资料,开展曾母和北康两盆地重处理二维地震剖面的构造-地层解译,以及联井剖面的井震对比,重新识别和标定新生代重要构造变革面的地震反射特征.根据海域钻井、地层岩性、沉积环境、构造应力体系和古生物资料的综合对比研究,结合婆罗洲陆地测年结果和区域构造事件,重新厘定中中新世T₃构造变革面的发育时代,年龄为15～17 Ma,分析了该界面的构造含义,认为其是南海海底扩张停止的一个构造响应界面,在南海南部海域对应南沙运动,在北婆罗洲地区表现为沙巴造山运动.

The seismic reflection characteristics and tectonic significance of the tectonic revolutionary surface of mid-Miocene (T3 seismic interface) in the southern South China Sea

Due to the large depositional thickness, quick changes of the strata facies and the complexity of tectonic evolution, it is very difficult and controversial to divide and date Cenozoic stratigraphic system in the southern South China Sea (SCS). In this work, all kinds of stratigraphic systems proposed by domestic and overseas scholars were compared and summarized, and the 2D seismic profiles by seismic reprocessing were interpreted using drilling data of two key wells obtained overseas, and the seismic reflection characteristics about key tectonic revolutionary surfaces were identified and divided. Based on the data of drilling, lithology, depositional environment, tectonic stress system and paleontology, combined with the tectonic events and the results of chronometry from Borneo, the development time about the tectonic surface of mid-Miocene (T₃ seismic interface) was determined. The analysis of this tectonic revolutionary surface showed that the sea-floor spreading of SCS stopped between 15～17 Ma which corresponded with Nansha Movement in the Southern SCS and with Sabah orogenic event in the northern part of Borneo.