Abstract. The Bohemian Massif exposes structures and metamorphic rocks remnant from the Variscan Orogeny in Central Europe and is bordered by the Franconian Fault System (FFS) to the west. Across the FFS, possible presence of Variscan units and structures are buried by Permo-Mesozoic sedimentary rocks. We integrate existing DEKORP 2D seismic reflection, well and surface geological data with the newly acquired FRANKEN 2D seismic survey to investigate the possible westward continuation of Variscan tectonostratigraphic units and structures, and their influence on latest to post-Variscan basin development. Subsurface Permo-Mesozoic stratigraphy is obtained from available wells and are tied to seismic reflection profiles using a synthetic seismogram calculated from density and velocity logs. Below the sedimentary cover, three main basement units are identified using seismic facies descriptions that are compared with seismic reflection characteristics of exposed Variscan units east of the FFS. Our results show that Upper Paleozoic low-grade metasedimentary rocks and possible Variscan nappes are bounded and transported by Variscan shear zones to ca. 65 km west of the FFS. Basement seismic facies in the footwall of the Variscan shear zones are interpreted as Saxothuringian basement. We show that the location of normal fault-bounded latest to post-Variscan Upper Carboniferous-Permian basins are controlled by the geometry of underlying Variscan shear zones. Some of these Upper Carboniferous-Permian normal faults reactivated as steep reverse faults during the regional Upper Cretaceous inversion. Our results also highlight that reverse reactivation of normal faults gradually decreases west of the FFS.

中文翻译：

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Variscan 结构及其对最新到后 Variscan 盆地结构的控制；来自最西端的波西米亚地块和德国东南部的见解

摘要。波西米亚地块暴露了中欧瓦利斯坎造山带的结构和变质岩残余，西部与法兰克断层系统 (FFS) 接壤。在整个 FFS 中，可能存在 Variscan 单元和结构被二叠纪-中生代沉积岩掩埋。我们将现有的 DEKORP 2D 地震反射、井和地表地质数据与新获得的 FRANKEN 2D 地震勘测相结合，以研究瓦里斯坎构造地层单元和结构可能向西延续的可能性，以及它们对瓦里斯坎后盆地最新发展的影响。地下二中生代地层是从可用井中获得的，并使用根据密度和速度测井计算的合成地震图与地震反射剖面相关联。在沉积盖层之下，使用地震相描述确定了三个主要基底单元，这些描述与 FFS 以东暴露的 Variscan 单元的地震反射特征进行了比较。我们的研究结果表明，上古生界低品位变质沉积岩和可能的 Variscan 推覆岩被 Variscan 剪切带包围并输送到约 FFS 以西 65 公里。Variscan 剪切带下盘的基底地震相被解释为 Saxothuringian 基底。我们表明，最晚到后瓦里斯坎上石炭纪-二叠纪盆地的正断层边界的位置受下伏瓦里斯坎剪切带的几何形状控制。这些上石炭纪-二叠纪正断层中的一些在区域上白垩统反转期间重新激活为陡峭的反向断层。