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珠江口盆地裂后期断裂作用对新近系油气成藏具有重要影响,但人们对其发育特征及动力学演化规律的认识一直不够.利用钻井约束的高精度三维及二维地震资料对珠一坳陷裂后期断裂的几何学与运动学特征进行了分析,结果表明珠一坳陷裂后期存在南海期和东沙期两期断裂作用,从南海期断裂作用到东沙期断裂作用,断裂的几何学、运动学特征以及动力学机制均发生了转换.南海期断裂作用具有从南向北迁移的特征;而东沙期断裂具有由东向西迁移的特征.两期断裂都以伸展为主,其中东沙期断裂具有微弱扭性特征.南海期断裂区域伸展方向为NNE10°~15°,东沙期为NNE20°~25°,区域伸展方向发生了5°~10°的顺时针偏转.南海期断裂作用发生于南海同扩张期,可能与南海扩张期间北部陆缘残留的伸展作用有关.东沙期断裂作用形成于南海后扩张期的东沙运动,该时期区域主应力轴σ_2方向与吕宋岛弧和欧亚大陆的挤压碰撞方向一致.东沙期断裂特征进一步证实了东沙运动是中中新世以来吕宋岛弧与欧亚大陆碰撞的结果.研究结果对整个南海地区裂后期南海运动与东沙运动的进一步认识具有重要意义.
The fracture of the Pearl River Mouth Basin at the late stage of fracture has an important influence on the hydrocarbon accumulation in the Neogene, but people’s understanding of its developmental characteristics and dynamic evolution has not been enough.Using drilling-constrained high-precision 3D and 2D seismic data, The results show that there are two stages of fault fracture in the South China Sea and the East Shashi period in the post-rifting period of the Zhuya depression, from the function of the South China Sea fault to the East Sharu fault, the geometry of the fault, the movement Characteristics and kinetic mechanism have been converted.The South China Sea fault has the characteristics of migrating from south to north, while the East Sharu fault has the characteristics of migrating from east to west.The two faults are mainly extensional, of which the East Sharu fault With weak twisting characteristics.The extensional direction of the South China Sea fault zone is NNE10 ° ~15 °, NNE20 ° ~25 ° in the East SST stage, and clockwise deflection of the zone extends in the range of 5 ° ~10 °. The fracture in the South China Sea occurred in the South China Sea The same period of expansion may be related to the extension of the northern margin of the South China Sea during the expansion of the South China Sea. The Dongsha period was formed during the Dongsha movement after the expansion in the South China Sea. During this period, The direction of stress axis σ_2 coincides with the direction of extrusion collision between Luzon arc and Eurasia continent.The characteristics of Dongsha fault also confirm the collision between Luzon arc and Eurasia since Dongsha movement was the middle Miocene. The South China Sea throughout the South China Sea during the split-stage movement and Dongsha movement to further understand is of great significance.