| 南海北部新生代盆地断裂系统及构造动力学影响因素 |
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| 引用本文： | 张远泽,漆家福,吴景富.南海北部新生代盆地断裂系统及构造动力学影响因素[J].地球科学,2019,44(2):603-625. |
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| 作者姓名： | 张远泽 漆家福 吴景富 |
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| 作者单位： | 1.中国石油大学油气资源与探测国家重点实验室, 北京 102249 |
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| 基金项目： | 国家自然科学基金委员会面上基金项目41572202 |
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| 摘 要： | 利用地震资料、油气勘探资料分析了南海北部大陆边缘珠江口-琼东南新生代盆地断裂系统的时空差异及动力学成因机制.珠江口-琼东南盆地古近系裂陷构造层以NE向、近EW向基底正断层构成的伸展断裂系统的几何学、运动学沿着盆地走向有明显变化,盆地内部隐伏的区域性和局部的NW向断裂及相关构造变形带构成伸展断裂系统之间的构造变换带.在空间上,区域性的云开、松涛-松南等NW向构造变换带以西为NE-NEE向正断层构成的"非拆离"伸展断层系,以东为NE向正断层、近EW向正断层(走滑正断层)复合而成的拆离伸展断层系.在时间上,古近纪裂陷作用可划分为早(文昌组沉积期)、中(恩平组/崖城组沉积期)、晚(珠海组/陵水组沉积期)3个有明显差异的裂陷期.裂陷早期,盆地西部以平面式正断层控制的简单地堑、半地堑为主,伸展量相对较小,东部则以铲式正断层控制的复式地堑、半地堑为主,伸展量相对大,断层向深部收敛在中地壳韧性层构成拆离的伸展断层系统.裂陷中期,琼东南盆地、珠江口盆地西部断裂具有继承性活动特点,珠江口盆地东部发育NWW-EW向伸展断层,并向深层切割早期浅层拆离断层,形成深层拆离伸展断层系统,而沿着云开构造变换带发育反转构造.裂陷晚期,琼东南盆地、珠江口盆地西部断裂具有活动性减弱特点,琼东南盆地东部发育NWW-EW向伸展断层,形成深层拆离伸展断层系统,而沿着琼中央构造变换带发育反转、走滑构造.珠江口-琼东南盆地不同区段断裂系统及其构造演化的差异性受盆地基底先存构造、地壳及岩石圈结构及伸展量等多方面因素的影响,拆离伸展断层系统与发育NWW向"贯穿"断裂的基底构造薄弱带、现今地壳局部减薄带相关,南海扩展由东而西的迁移诱导北部大陆边缘块体沿着先存NW向深大断裂发生走滑旋转是导致变换构造带两侧差异伸展的动力学原因,应力场及岩石圈热结构变化是引起拆离断层深度变化的重要因素.
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| 关 键 词： | 断裂构造 拆离断层 构造差异性 变换带 构造动力学 南海北部 |
| 收稿时间： | 2018-12-09 |
Cenozoic Faults Systems and Its Geodynamics of the Continental Margin Basins in the Northern of South China Sea |
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| Zhang Yuanze,Qi Jiafu,Wu Jingfu.Cenozoic Faults Systems and Its Geodynamics of the Continental Margin Basins in the Northern of South China Sea[J].Earth Science-Journal of China University of Geosciences,2019,44(2):603-625. |
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| Authors: | Zhang Yuanze Qi Jiafu Wu Jingfu |
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| Affiliation: | (State Key Lab of Petroleum Resources and Prospecting,China Petroleum University,Beijing 102249, China;Department of Earth Sciences,China Petroleum University,Beijing 102249, China;CNCXXJ Research Institute,Beijing 100027, China) |
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| Abstract: | We employ recently updated seismic reflection data to investigate spatial-temporal difference of Cenozoic faults systems and its dynamic mechanism of the Pearl River Mouth Basin and Qiongdongnan Basin in the Northern of South China Sea.It shows geometry, kinematics of extensional faults systems in the Paleogene rift zone of the Pearl River Mouth basin and Qiongdongnan basin change significantly along strike, which is composed of NE-and EW-trending normal basement faults.The concealed regional and local NW-trending faults with associated deformation zone constitute the transfer zones between the extensional faults systems.The "non-detachment" extensional fault system consists of NE-and NEE-trending normal faults to the west of NW-trending Yunkai and Songtao-Songnan transfer zones, and the detachment fault system is composed of NE-and EW-trending normal/strile-slip faults to the east.Paleogene rifting experienced three distinguished stages.In the early period (Wenchang Formation), simple (half) grabens in western basins was controlled by planar normal faults with relatively small extension, and composite (half) grabens in eastern basins are dominated by listric normal faults with large extension, where normal faults converge and terminate at detachment fault within mid-crust.In the middle period (Enping/Yacheng Formation), faults in the west are characterized by inherited activity, whereas NWW-and EW-trending faults in the east of Pearl River Mouth Basin form deep detachment system by cutting antecedent mid-crust detachment fault, with inversion along the Yunkai transfer zone.In the late stage (Zhuhai/Lingshui Formation), the activities of faults decline in the west, whereas NWW-and EW-trending faults form deep detachment system in the east of the Qiongdongnan Basin, with inversion and strike-slip structures along the Songtao-Songnan transfer zone.The influencing factors of differential fault systems and tectonic evolution include pre-existing basement fabrics, rheology of crust and lithosphere, and extension amount.The detachment systems are associated with the NWW-trending throughgoing crustal faults within basement weak belts and present local crustal thinning zone, the geodynamic mechanisms for differential extension on both sides of the transfer zones result from the strike-slip movement along the NWW-trending pre-existing faults induced by the opening of the South China Sea from east to west, and changes of the stress field and lithospheric thermal structure account for the depth variation of the detachment systems. |
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| Keywords: | fault structure detachment fault differential tectonics transfer zone geodynamic Northern South China Sea |
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