桑托斯盆地历经早白垩世早期克拉通坳陷盆地、早白垩世早—中期裂谷盆地、早白垩世晚期至全新世大陆边缘盆地3个演化阶段,石油资源主要富集于裂谷盆地的生储盖组合中,目前的盆地构造单元划分方案不能够准确地反映裂谷期的构造格局.根据最新的重磁、地震、钻井、大洋钻探等基础资料,提出了桑托斯盆地盐下构造单元划分的新方案:①以晚断陷期主要断裂和沉积特征作为划分一级构造单元的依据,根据断裂分布结合晚断陷期沉积厚度600m等值线确定隆起与坳陷的边界,②以晚断陷期次级断裂和沉积特征作为划分二级构造单元的依据,根据同沉积拉张断裂、二级走滑断裂及其调节断裂分布,结合晚断陷期和早坳陷期沉积厚度1000m等值线确定凸起和凹陷的边界,③将盆地划分为"二隆三坳"5个一级构造单元,包括西部坳陷、阿鸟隆起、中央坳陷、卢苏隆起和东部坳陷,并进一步划分为38个二级构造单元.以裂谷盆地构造演化特征为主要依据划分的构造单元对未来油气勘探选区和资源评价具有重要意义.

Santos Basin has experienced three evolution stages: Early Cretaceous craton depression basin, early and middle Early Cretaceous rift basin and late Early Cretaceous Albian - Holocene continental margin basin. Oil resources are mainly enriched in the source-reservoir-cap assemblage of rift basin. The current division scheme of basin tectonic units can not accurately reflect the tectonic framework of rift period. According to the latest basic data of gravity and magnetism, seism, drilling and ocean drilling, a new scheme for the division of subsalt tectonic units in Santos basin is put forward: (1) Taking the main faults and sedimentary characteristics in the late fault depression period as the basis for the division of primary tectonic units, the boundary between uplift and depression is determined according to the faults distribution and the isoline of sedimentary thickness of 600 m in the late fault depression period. (2) Taking the secondary faults and sedimentary characteristics in the late fault depression stage as the basis for dividing the secondary tectonic units, the boundaries of bulges and sags are determined according to the distribution of synsedimentary tension faults, secondary strike slip faults and their regulating faults, combined with the 1000 m isoline of sedimentary thickness in the late fault depression stage and early depression stage. (3) The basin is divided into five primary structural units of "two uplifts and three depressions", including western depression, Aram-U uplift, central depression, Lula-Sugar uplift and eastern depression, and further divided into 38 secondary structural units. The tectonic units division based on the evolution characteristics of rift basins are of great significance for future oil and gas exploration and resource evaluation.