Abstract. Using 3D reflection-seismic data constrained by wells, we address the kinematic connections between Permian Zechstein evaporites, basin-inversion structures in the sedimentary units above, and reactivated structures in the sub-salt basement in the Danish Central Graben. The Danish Central Graben is part of the failed North Sea rift system. Where present, mobile Zechstein evaporites have played a significant role in its structural development since the Triassic, while tectonic shortening caused mild inversion in the Late Cretaceous and Paleogene. Shortening was accommodated mainly by reverse reactivation of older normal faults (i.e. fault inversion) along with folding and uplift of their hangingwalls. Within the study area, rifting generated two major W-SW-dipping basement faults with several kilometres of normal offset. The larger Coffee Soil Fault delineate the eastern boundary of the rift basins. Within its hangingwall, a broad zone is characterised by inversion-related uplift and deformation. Along the fault, buttressed growth folds in the immediate hangingwall indicate thick-skinned inversion, i.e. coupled deformation between the basement and cover units. The opposite margin of the inverted zones follows the westwards pinch-out of the Zechstein salt. Here, thin-skinned folds and faults sole out into Zechstein units on the half-graben dip slopes. The most pronounced inversion occurred directly above and in extension of salt ridges and –rollers that localized shortening in the cover above. With no apparent links to underlying basement faults, we balance thin-skinned shortening to the sub-salt basement via a triangle-zone concept. This implies that thin Zechstein units on the half-graben dip slopes formed thrust detachments during inversion, and that basement shortening was mainly accommodated by reactivation of the major rift faults further east. Ductile deformation at seismic scales accounts for thin-skinned shortening of the cover units where such a detachment did not develop. We discuss the related mechanisms. The documented structural styles are similar to those found in other inverted basins in the region, and to those produced from physical-model experiments. Our results indicate that Zechstein units imposed a strong control on structural style and kinematics during basin inversion in large parts of the Danish Central Graben. We emphasize that even thin evaporite units may act as detachments during tectonic extension and contraction if favourably orientated. Salt ridges and diapiric structures can localise shortening and generate thin-skinned faults and folds in the cover above. In mildly inverted rifts, extensive mobile salt may mask the effects of basin inversion if shortening is accommodated by salt structures without the formation of clearly defined inversion structures at the surface or significant uplift.

中文翻译：

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北海丹麦中部格拉本中厚薄皮盆地反演-深层蒸发岩和基底运动学的作用

摘要。使用受井约束的3D反射地震数据，我们解决了二叠纪Zechstein蒸发岩，上方沉积单元中的盆地倒置结构以及丹麦中部Graben盐下基底的重新活化结构之间的运动学联系。丹麦中部Graben是北海裂谷系统失效的一部分。自三叠纪以来，流动的Zechstein蒸发岩在其结构发育中起着重要作用，而构造缩短则在白垩纪晚期和古近纪造成了轻度的倒转。缩短主要通过较老的正常断层的逆向激活（即断层反转）以及其上盘的折叠和抬升来解决。在研究区域内，裂谷产生了两个主要的W-SW浸入地下室断层，其正常偏移量为数公里。较大的咖啡土壤断层描绘了裂谷盆地的东部边界。在它的吊壁内，一个宽阔的区域以与反转有关的隆起和变形为特征。沿断层，紧邻的上盘壁中成堆的生长褶皱表明皮肤厚厚的倒置，即地下室和盖层单元之间的耦合变形。反向带的相对边缘跟随Zechstein盐的向西挤压。在这里，稀薄的褶皱和断层在半陡倾斜坡上突出成Zechstein单元。最明显的反演发生在盐脊和滚子的正上方和延伸处，盐分和滚子在上盖中局部缩短。由于没有明显的与地下基底断层的联系，我们通过三角带概念将薄皮起酥油与盐下基底平衡。这意味着，在反演期间，半graben倾角斜坡上的薄Zechstein单元形成了冲断分离，并且基底的缩短主要是通过重新激活了东侧的主要裂谷断层来解决的。地震尺度下的延性变形导致覆盖单元的皮肤变薄，而这种分离并没有发展。我们讨论了相关的机制。记录的结构样式与在该地区其他倒置盆地中发现的样式相似，并且与通过物理模型实验得出的样式相似。我们的结果表明，Zechstein单元在丹麦中部Graben大部分地区的盆地倒置过程中对结构样式和运动学施加了强有力的控制。我们强调，如果方向有利，即使薄的蒸发岩单元也可能在构造伸展和收缩过程中起脱离作用。盐脊和底基结构可以局部缩短并在上面的盖层中产生薄层的断层和褶皱。在轻度倒立的裂谷中，如果盐结构调节了起酥油而没有在表面形成明确定义的倒置结构或明显隆起，大量的流动盐可能掩盖盆地倒置的影响。