Upper Permian (Zechstein Supergroup) evaporites have a major control on structural styles and prospectivity in the UK Southern North Sea (SNS). They form the regional super-seal for the main Rotliegend Group (Leman Sandstone Formation) reservoir play fairway immediately beneath. The evaporites have highly variable thicknesses due to the syndepositional basin architecture, differential loading and post-depositional deformation through diapirism and salt withdrawal. The halokinetic activity leads to touchdown (welding) of the supra-salt section onto the sub-salt strata and the development of narrow (up to 15 km-wide) graben systems. The interpretation and depth conversion of well-calibrated, high-quality, 3D post-stack time-migrated (PSTM) seismic data along the southwestern margin of the basin show that a NW–SE-striking elongate extensional Dowsing Graben System transects the area. The graben is defined by a series of large, overlapping, en echelon listric growth faults, with oblique secondary planar faults, which sole-out on two main (deep and shallow) decollement levels in the Zechstein Supergroup and the Middle Triassic Rot Halite Member. Whilst its initial formation was related to Mesozoic extension, the graben system also displays a contractional overprint resulting from regional compression and structural inversion during the Cenozoic. Detailed mapping of the Zechstein Supergroup has revealed that the evolution of the extensional system was influenced by the ESE–WNW-striking anhydrite–carbonate Zechstein shelf-margin. The occurrence of variable-thickness, low-velocity sediments within the graben impacts seismic imaging and depth conversion, leading to prospective structures being overlooked; something that has implications for prospectivity in the SNS and other evaporite basins where similar graben occur.

中文翻译：

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道辛地堑系统的演变：对英国南北海石油勘探的影响

上二叠纪（Zechstein 超群）蒸发岩对英国南北海 (SNS) 的构造样式和远景有主要控制。它们形成了位于下方的主要 Rotliegend Group（Leman Sandstone Formation）水库球道的区域超级密封。由于同沉积盆地结构、不同载荷和沉积后变形（通过底辟作用和脱盐作用），蒸发岩的厚度变化很大。盐动力活动导致盐上部分触地（焊接）到盐下地层上，并形成狭窄（宽达 15 公里）地堑系统。校准良好、高质量、沿盆地西南缘的 3D 叠后时间偏移 (PSTM) 地震数据表明，一个 NW-SE 走向的细长伸展探矿地堑系统横切该地区。地堑由一系列大的、重叠的、成梯形的生长断层定义，带有倾斜的次生平面断层，在 Zechstein 超群和中三叠世 Rot Halite 岩段的两个主要（深和浅）滑脱层上唯一出露。虽然其初始形成与中生代伸展有关，但地堑系统也显示出由于新生代区域压缩和构造反转导致的收缩叠印。Zechstein 超群的详细映射表明，伸展系统的演化受到 ESE-WNW 冲击的硬石膏-碳酸盐 Zechstein 货架边缘的影响。地堑内变厚、低速沉积物的出现影响地震成像和深度转换，导致远景构造被忽视；这对 SNS 和其他发生类似地堑的蒸发岩盆地的前景有影响。