Late Cretaceous to recent tectonic evolution of the North German Basin and the transition zone to the Baltic Shield/southwest Baltic Sea
Late Cretaceous to recent tectonic evolution of the North German Basin and the transition zone to the Baltic Shield/southwest Baltic Sea
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DOI：
10.1016/j.tecto.2017.04.021
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发表时间：
2017-06
期刊：
影响因子：
2.9
通讯作者：
M. A. Hseinat;Christian Hübscher
中科院分区：
文献类型：
--
作者：
M. A. Hseinat;Christian Hübscher
本研究以密集的地震反射剖面网格为基础，研究了波罗的海西南部晚白垩世至近代的构造演化。该区域包括受盐影响的北德意志盆地的波罗的海部分及其跨越Tornquist带向无盐波罗的海地盾的过渡。通过单独的地震剖面和得到的主要层位（即上白垩世、第三纪和更新世）的高分辨率时间结构图，讨论了上白垩世到最近的构造演化。上白垩统和第三系在整个研究区内发现了许多重要的断层。其中一些断层向上延伸，穿过未固结的更新世沉积层，偶尔穿透地表。盐作用下的北德意志盆地呈现出NW-SE、N-S和NNE-SSW三大断裂走向。其中一些断层位于基底（盐下）断层和盐枕的正上方。这些断裂大部分走向北南-北北-南西，与gl<s:1> ckstadt地堑断裂方向平行。在无盐的Tornquist带，我们确定了两个主要的浅层断裂走向，即NW-SE和NE-SW。这些断层大部分位于基底断层之上，沿Tornquist带方向发育。基底构造控制着浅层断裂的活动和走向。如果盐存在，韧性盐层会引起盐下断层和盐上断层之间的横向移动。与非洲-伊比利亚-欧洲融合和随后的高山造山运动有关的主要板块重组导致了晚白垩世原有断层的重新激活和垂直盐运动。新近纪应力方向由NE-SW向NW-SE转变，引起了另一阶段的断盐构造再活化。我们解释说，冰盖负荷和/或今天的应力场可能是共同作用的，导致了最近的构造和断层的向上延伸。
In this study we investigate the Late Cretaceous to recent tectonic evolution of the southwestern Baltic Sea based on a dense grid of seismic reflection profiles. This area covers the Baltic Sea sector of the salt influenced North German Basin and its transition to the salt free Baltic Shield across the Tornquist Zone. The Upper Cretaceous to recent structural evolution is discussed by means of individual seismic sections and derived high-resolution time-structure maps of the main horizons, i.e., the Upper Cretaceous, Tertiary and Pleistocene. The Upper Cretaceous and Tertiary layers reveal numerous significant faults throughout the study area. Several of these faults propagate upwards across the unconsolidated Pleistocene sediments and occasionally penetrate the surface. The salt influenced North German Basin reveals three major fault trends: NW-SE, N-S and NNE-SSW. Several of these faults are located directly above basement (sub-salt) faults and salt pillows. The majority of these faults are trending N-S to NNE-SSW and parallel the direction of the Glückstadt Graben faults. In the salt free Tornquist Zone, we identify two major shallow fault trends, which are NW-SE and NE-SW. The majority of these faults are located above basement faults, following the direction of the Tornquist Zone. We conclude that generally basement tectonics controls activation and trends of shallow faults. If salt is present, the ductile salt layer causes a lateral shift between the sub- and supra-salt faults. Major plate reorganisation related to the Africa-Iberia-Europe convergence and the subsequent Alpine Orogeny caused reactivation of pre-existing faults and vertical salt movement in the Late Cretaceous. The change of stress orientation from NE-SW to a NW-SE during Neogene caused another phase of fault and salt tectonic reactivation. We explain that the ice-sheet loading and/or present-day stress field may have acted in combination, causing the recent tectonics and upward extension of the faults.