By integrating structural geology method with stratigraphy analysis, multiple 2D seismic sections are interpreted,the structure is restored and balanced,and the extensional magnitude and rates are calculated. The results reveal the development process of Saihantala sag, and help to understand the general internal architecture and forming mechanism of Erlian Basin. The study indicates that the development of Saihantala sag mainly consists of three stages, that is, early stage of faulting/rifting, middle unbalanced stage with depression and uplift co-existed and late stage of regional depression with overlapping deposits. The early faulting mainly happens when Aershan formation and Tenggeer formation subunit 1 are deposited; while Tenggeer formation subunit 2 is deposited, the basin is undergoing differential depression and uplifting, with local subsidence still controlled by faulting. With the deposition of Tenggeer formation, the basin is characterized by regional depression and development of unconformity due to overlapping,and the basin is close to die out. The whole basin can be divided into three sub tectono-se-quences or basin facies that are controlled by different tectonics, e. G. The lower rifting basin (Aershan formation and Tenggeer formation subunit 1), middle detachment basin (Tenggeer formation subunit 2 and Saihantala formation), and upper basin dominated by thermal decay or tectonic inversion. The result of this study will be beneficial to the hydrocarbon exploration in other sags in Erlian Basin with similar genesis and structure styles.%本文采用构造地质学的研究方法,通过选取多条地震剖面进行二维构造-地层解释和平衡恢复,揭示了赛汉塔拉凹陷的发育过程,了解了二连盆地的总体结构特征和形成机制,结果表明:赛汉塔拉凹陷表现为下部断陷、中部不均衡隆起和拗陷并存、上部超覆拗陷的基本特征;严格受正断层活动控制的沉降主要发生于阿尔善组和腾格尔组一段沉积时期,在腾格尔组二段沉积时期,盆地发生不均衡隆起和拗陷,部分地域的沉降仍受到断裂活动的控制;在赛汉塔拉沉积期主体表现为区域性拗陷沉降和超覆不整合发育,盆地接近消亡;全盆地大体可划分为三个亚构造层序或盆地相,即下部裂陷盆地相(阿尔善组和腾格尔组一段)、中部拆离盆地相(腾格尔组二段和赛汉塔拉组)和上部热衰减或构造反转盆地相,它们分别受控于不同的构造作用过程.研究结果对二连盆地西南部具有相同成因类型和构造样式的其他凹陷的油气勘探具有参考价值.
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