Inversion tectonics at the northern margin of the North German Basin: Cretaceous to recent reactivation of Triassic normal faults (iTec-NGB)

北德盆地北缘的反转构造：白垩纪到三叠纪正断层的近期重新活动（iTec-NGB）

• 批准号: 465329435
• 负责人: Professor Dr. Christian Hübscher
• 金额: --
• 依托单位: Institut for Geoscience
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2021
• 资助国家: 德国
• 起止时间: 2020-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/465329435?language=en
• 关键词: Inversion; tectonics; northern; margin; North

Near-surface faults within late Pleistocene, possibly Holocene strata are located in the eastern prolongation of a west-east striking graben across Langeland Island (Danish sector of the Baltic Sea) and correlate with deep-rooted faults within Triassic and Cretaceous strata. These faults are located above a prominent basement horst structure of the Ringkøbing-Fyn High, which marks the northern margin of the North German Basin (NGB). This project strives for investigating the tectonic evolution of the northern NGB margin east of Langeland Island and its relation to the post-Permian to recent evolution of the NGB by means of seismic interpretation. The study area allows investigating the early phases of basin formation dominated by extension and corresponding development of basin margin normal faults during the Triassic, their compressional reactivation as reverse faults during Late Cretaceous and Cenozoic basin inversion, and possible recent tectonic movements as well as post-glacial isostatic adjustments. In 2020, 27 high-resolution multi-channel reflection seismic and parametric echosounder profiles have been collected east of Langeland. To reveal the complex multiphase evolution of the northern NGB margin, these data have to be processed, interpreted and discussed within the tectonic framework. A first data example indicates the reactivation of normal faults, bounding tilted Triassic blocks, as reverse faults that uplifted overlying Cretaceous strata and pierce into overlying Pleistocene units. However, the exact outline of the fault system remains unknown. Incorporating more seismic data into the interpretation will improve the understanding of fault system evolution and reveal its exact outline and connection to deep-seated structures of the Ringkøbing-Fyn High. The quantitative analysis of fault displacement requires seismic depth sections obtained by high-quality velocity models. Migration velocity model building will be achieved by using an innovative processing flow based on a diffraction extraction technique. This technique uses diffraction wavefront attributes to calculate lateral variable velocity information even for short-offset seismic data. Additionally, extracted diffractions will help to identify faults and improve the understanding of the fault system and its geometry. Growth faulting visible in the produced depth sections will allow quantification of active phases of tectonic movement, which will be discussed in the context of the known phases of basin subsidence and inversion from other areas of the NGB and adjacent sub-basins of the Central European Basin System.

晚更新世，可能是全新世地层中的近地表断裂位于横跨朗兰岛(波罗的海的丹麦部分)的西向东向地块的东部延伸处，与三叠纪和白垩纪地层中的深层次断裂相关。这些断层位于标志着北德盆地(NGB)北缘的RingkøBing-Fyn High的突出的基底地垒结构之上。本项目致力于通过地震解释手段研究朗兰岛以东NGB北缘的构造演化及其与后二叠世至现代演化的关系。该研究区可以研究三叠纪以盆缘正断层的伸展和相应发育为主导的盆地形成的早期阶段，晚白垩世和新生代盆地反转时的挤压再活动，以及可能的现代构造运动和冰期后的均衡调整。2020年，在朗格兰以东地区共采集到27条高分辨率多道反射地震和参数测深剖面。为了揭示北NGB边缘复杂的多期演化，必须在构造框架内对这些数据进行处理、解释和讨论。第一个数据实例表明，作为反向断层，包围倾斜的三叠纪地块的正常断层重新激活，抬升了上覆的白垩纪地层，并刺入了上覆的更新世单元。然而，断层系统的确切轮廓仍然未知。在解释中加入更多的地震数据将提高对断裂系统演化的理解，并揭示其确切的轮廓及其与RingkøBing-Fyn High的深层结构的联系。断层位移的定量分析需要高质量的速度模型获得地震深度剖面。利用一种基于绕射提取技术的创新处理流程，实现偏移速度模型的建立。该技术利用绕射波阵面属性来计算横向变速信息，即使对于小炮检距的地震资料也是如此。此外，提取的衍射图将有助于识别断层，并提高对断层系统及其几何形状的理解。在生产的深度剖面中可见的生长断层将使构造运动的活跃期得以量化，这将在NGB其他地区和中欧盆地系统相邻子盆地的已知盆地沉降期和反转的背景下讨论。