巴西东北部海域盆地重力滑脱构造体系特征

GRAVITY DCOLLEMENT STRUCTURAL SYSTEM IN OFFSHORE BASINS OF NORTHEAST BRAZIL

重力滑脱构造是被动大陆边缘盆地广泛发育的一种构造样式。从重力滑脱构造的形成机制出发,分析并指出巴西东北部海域盆地重力滑脱构造主要分布区域有:福斯杜—亚马逊、帕拉—马拉尼郝和巴雷里尼亚斯盆地深水区;进而对这3个盆地的重力滑脱构造特征进行分析,明确了重力滑脱伸展区、平移区、冲断区的构造样式及圈闭发育类型。其中,福斯杜—亚马逊盆地重力滑脱构造最为发育且圈闭类型多样,受漂移晚期重力滑脱作用影响形成的伸展和冲断构造是盆地的主要圈闭类型。最后,论述了福斯杜—亚马逊盆地重力滑脱构造对油气的控制作用及其勘探潜力。

The gravity décollement structure is a typical structural style in passive continental margin basins.This paper,based on mechanism analysis of gravity décollement structures,suggests that the gravity décollement structures in Northeast Brazil are mainly distributed in the deepwater area of the Foz do Amazon,Para-maranihao and Barreirinhas Basins.Then,the characteristics of gravity décollement structure were studied to find out the structural and trap types in stretch zone,transition zone and thrust zone.Among the basins in offshore Northeast Brazil,the Foz do Amazon basin has the most typical gravity décollement structure and various trap types.The stretching and thrust structures,which are controlled by gravity gliding since late drift period,are the main trap types.Finally,this paper discussed the roles of gravity décollement structure in hydrocarbon accumulation in the Foz do Amazon basin,and further analyzed the exploration potential of gravity décollement zone in this basin.