石晓光. 珠江口盆地恩平凹陷新生代断裂特征与盆地成因[J]. 海洋地质前沿,2021,37(12):1-9. DOI: 10.16028/j.1009-2722.2021.167
    引用本文: 石晓光. 珠江口盆地恩平凹陷新生代断裂特征与盆地成因[J]. 海洋地质前沿,2021,37(12):1-9. DOI: 10.16028/j.1009-2722.2021.167
    SHI Xiaoguang. CENOZOIC FAULT CHARACTERISTICS AND BASIN GENESIS OF THE ENPING SAG, PEARL RIVER MOUTH BASIN[J]. Marine Geology Frontiers, 2021, 37(12): 1-9. DOI: 10.16028/j.1009-2722.2021.167
    Citation: SHI Xiaoguang. CENOZOIC FAULT CHARACTERISTICS AND BASIN GENESIS OF THE ENPING SAG, PEARL RIVER MOUTH BASIN[J]. Marine Geology Frontiers, 2021, 37(12): 1-9. DOI: 10.16028/j.1009-2722.2021.167

    珠江口盆地恩平凹陷新生代断裂特征与盆地成因

    CENOZOIC FAULT CHARACTERISTICS AND BASIN GENESIS OF THE ENPING SAG, PEARL RIVER MOUTH BASIN

    • 摘要: 以恩平凹陷为主要研究对象,在断裂体系及盆地结构的精细刻画的基础上,结合断层活动速率计算和平衡剖面分析,恢复盆地发育演化过程,揭示盆地动力学成因机制。结果表明,盆地的发育演化过程受基底先存构造与区域动力背景联合控制。裂陷早期:太平洋板块俯冲速率降低及俯冲带后撤与印度板块俯冲联合作用下,导致了NW—SE向拉张应力场环境,造成了早期NE向低角度逆断层负反转,形成了NE向断裂控制的拆离半地堑;裂陷晚期:印支地块旋转挤出与古南海向南俯冲联合作用下,导致应力场由NW—SE向拉张转变为近SN向拉张,造成了控盆断裂由NE向向近EW向转变,岩石圈伸展模式由宽裂谷方式向窄裂谷方式转变,造成了盆地格局由孤立半地堑趋于相互连通扩展;裂陷拗陷期:岩石圈减薄中心向南迁移至南海扩张中心,整体处于裂后热沉降阶段;构造活化期:吕宋岛弧NWW向与欧亚板块发生弧-陆碰撞作用下,产生NNE向拉张,派生近EW向和NW向的共轭剪切作用,造成了先存近EW断裂复活及次级走滑断裂带的形成,导致了复杂断块升降运动。

       

      Abstract: Detailed description of fault systems and basin structures is devoted by this paper to the Enping Sag of the Pearl River Mouth Basin, South China Sea. The main basin controlling fault systems formed in different periods are determined and classified by means of fault activity rate calculation and equilibrium profile analysis, upon which the evolution process of the basin is reconstructed, and the dynamic mechanism of basin development and transformation discussed. The results suggest that the evolution of the basin is controlled by both the pre-existing basement structure and the regional dynamic field. During the early rifting stage, the subduction of the Pacific plate retreated as the subduction rate decreased under the joint action of Indian plate, that led to the change in stress into an extension field in NW—SE direction and the negative inversion of the early formed NE trending low angle reverse faults. As the results, a detached half graben was formed under the control of NE trending fault. During the late rifting stage, under the joint action of the rotation and extrusion of Indosinian block and the southward subduction of the paleo-South China Sea, the regional stress field changed from clockwise transformation into nearly NS stretching, and the basin controlling faults changed from NE to nearly EW trending. And the lithospheric extension was changed from a wide rift mode to a narrow rift mode as the basin framework changed from isolated half grabens to connected extensional grabens. During the depression period, the lithospheric thinning center migrated towards the South China Sea spreading center, leading to weak tectonic activity and thermal subsidence. In the tectonic reactivation stage, the NW trending Luzon island arc collided with the Eurasian plate, which caused the NNE stretching, the revival of pre-existing near EW faults and the formation of the secondary strike slip fault zone, in addition to complex uplifting and falling of fault blocks.

       

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