王首良,李元昊,马婷钰,等. 滨里海盆地早二叠世孔谷期盐构造特征及其形成机制[J]. 海洋地质前沿,2024,40(1):65-78. DOI: 10.16028/j.1009-2722.2022.298
    引用本文: 王首良,李元昊,马婷钰,等. 滨里海盆地早二叠世孔谷期盐构造特征及其形成机制[J]. 海洋地质前沿,2024,40(1):65-78. DOI: 10.16028/j.1009-2722.2022.298
    WANG Shouliang, LI Yuanhao, MA Tingyu, et al. The salt structure characteristics and formation mechanism of Early Permian Kungurian in Pre-Caspian Basin[J]. Marine Geology Frontiers, 2024, 40(1): 65-78. DOI: 10.16028/j.1009-2722.2022.298
    Citation: WANG Shouliang, LI Yuanhao, MA Tingyu, et al. The salt structure characteristics and formation mechanism of Early Permian Kungurian in Pre-Caspian Basin[J]. Marine Geology Frontiers, 2024, 40(1): 65-78. DOI: 10.16028/j.1009-2722.2022.298

    滨里海盆地早二叠世孔谷期盐构造特征及其形成机制

    The salt structure characteristics and formation mechanism of Early Permian Kungurian in Pre-Caspian Basin

    • 摘要: 滨里海盆地为自寒武系以来多期沉降的大型叠合含盐盆地,也是世界上油气资源最丰富的大型沉积盆地之一。下二叠统孔谷阶含盐层系在全盆皆有分布,岩盐层具有厚度大、分布广、后期变形构造样式多等特征,但厚层岩盐形成机制尚有争议,盐构造变形类型、空间组合分布规律、变形主控因素等尚不明确。为了研究盆地巨厚盐构造的形成机制及分布规律,在深入了解区域地质背景基础上,利用二维地震剖面资料,采用平衡剖面恢复方法,从全盆地的角度分析盆地演化过程与盐构造变形样式及分布规律,并探讨了盆地盐构造形成演化过程及触发机制。结果表明,盐岩变形程度由盆地中央向盆地边缘减小,由盆缘盐滚、盐背斜构造向盆地中心盐墙构造变化,呈现分带特征。盐岩层的变形对盐下地层影响较小,地层连续性较好;对盐上地层穿插切割较强,导致盐上地层连续性差,形变剧烈。先存斜坡和盆缘的挤压作用是盐岩层最初开始形变的因素,而上覆地层的差异负载作用是盐岩层发生构造变形的主导因素。滨里海盆地连续且巨厚的致密盐岩层是一个天然盖层,阻止了油气向上运移,盐下地层应是未来油气勘探的重点目标,同时,局部岩盐变形消失后使上下地层连接,利于油气向上运移成藏,形成盐上油气勘探目标区。

       

      Abstract: The Pre-Caspian Basin is a large superimposed salt-bearing basin, which is also one of the largest sedimentary basins with the richest oil and gas resources in the world. The Kungurian Stage salt-bearing strata are distributed throughout the basin. The salt beds are very thick and widely developed in salt structural units. There are many structural types and different influencing factors. Due to the nature of salt rock itself and the particularity of deformation, the factors affecting structural deformation are diverse and complex. To study the influencing factors on the deformation of the huge thick salt structures in the basin, we scrutinized the evolution process of the basin from the perspective of the whole basin and analyzed the characteristics of the salt structure in the whole basin by using 2D seismic profile data and regional geological data. The formation and evolution of salt structure in the basin and its triggering mechanism are discussed through the restoration of balanced profile. Results show that the deformation degree of salt rock decreases from the center of the basin to the edge of the basin, showing zoning characteristics. The compressional action of preexisting slope and basin margin is the factor of initial deformation of salt rock, and the differential loading of overlying strata is the dominant factor of structural deformation of salt rock. The strata beneath salt beds have good continuity and weak deformation duo to the existence of salt rock, while the upper salt layer is poorly continuous and severely deformed. Therefore, the continuous and extremely thick salt bed in the Pre-Caspian Basin is a natural cap rock, and the reservoir under the salt is good, which should be the focus of oil and gas exploration in the future.

       

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