南美西北部典型含油气盆地构造特征

Structural Characteristics of Typical Oil-Bearing Basins in Northwest of South America

依据盆地处于造山弧的位置不同,将南美西北部盆地群分为弧前盆地、弧内盆地和弧后盆地三类。同一动力学背景下在不同构造部位形成了三类盆地不同的构造特征。弧前盆地具有地垒-地堑式裂陷盆地特点,发育断块油气藏,是安第斯俯冲增生带之上的近东西向张性盆地;弧内盆地位于强烈挤压隆升的造山带之内,是造山带内局部变形相对较弱的地区,发育叠瓦逆冲断层、双重构造和冲起构造;弧后盆地以逆断层反转构造和低幅度背斜构造为主,断裂系统具有走滑性质,是斜向弱挤压环境下的产物,构造平面上具东西向分带的特点,圈闭类型主要是低幅度背斜和岩性圈闭。

Sedimentary basins in northwest of South America are divided into three types： fore-arc basins, innerarc basins and back-arc basins. The three types of basins show different structural characteristics as they lie in different tectonic location, even if they were in the same dynamic setting. Fore-arc basin is one type of tensional rift basins developed along the Andes subduction zone. It developed a series of horst and graben systems and hydrocarbon reservoirs are developed in some fault blocks. Inner-arc basin is developed in the relatively weak deformed area within Andes orogen and is characterized by imbricate thrust, duplex and lifting. Oil fields are found rarely in inner-arc basins for poor preservation. Back-arc basin is generated from oblique weak compression. Its dominat structures are reversed abnormal faults and low-amplitude anticlines and the fault system is strike slip faults. Back-arc basin is characterized by zonation along EW direction, and its traps are low-amplitude anticlines and depositional traps. It is also the best oil-bearing basin of northwest of South America.