南海中北部深地震剖面综合地球物理解译及其构造意义

INTEGRATED GEOPHYSICAL RESEARCH IN THE MIDDLE-NORTHERN CONTINENTAL MARGIN OF THE SOUTH CHINA SEA BASED ON WIDE-ANGLE SEISMIC PROFILE OBS2006-3

利用2006年南海进行的深地震剖面和重磁数据,对南海中北部陆缘横跨东沙隆起和潮汕坳陷,延伸至海盆边缘的OBS2006-3地震剖面进行了反演。结合地质地球物理资料,对该剖面进行了地球物理综合解译,探讨了中生代古俯冲带、潮汕坳陷属性等科学问题,结果显示现今的东沙断裂很可能是中生代古俯冲带的遗存;潮汕坳陷为一个中生代残留的弧前盆地,沉积层厚达9km,具有较大的油气潜力,后期的岩浆活动和变质作用对其有一定改造影响。

The OBS2006-3 profile located in the northeastern South China Sea （SCS）, as an integrated en- deavor of geophysical research, passes through the Dongsha Islands and the Chaoshan Depression, and ends at the margin of the ocean basin. Density modeling remains the pivotal part of the research. Based on the model, combined with the geological and geophysical data available, it is revealed that： （1） A Mesozoic subduction zone might occur in the sea area around the Dongsha Islands, which might be the same as the East Asia subduction system. The Dongsha fault is probably the paleo-suture zone, and the Chaoshan de- pression might be the Mesozoic fore-arc basin, and the Dongsha-Peikang uplift might be a paleo-volcanic arc. （2） The thickest Mesozoic in the Chaoshan depression is around -9 km with oil and gas potential. There may be magmatic intrusions and/or metamorphism to certain extent.