The neotectonic evolution of the Osning Lineament derived from near-surface reflection seismic data

根据近地表反射地震数据得出的奥斯宁线的新构造演化

• 批准号: 451088796
• 负责人: Dr. Sonja Wadas
• 金额: --
• 依托单位: Sektion 1: Seismik und Potenzialverfahren
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/451088796?language=en
• 关键词: neotectonic; evolution; Osning; Lineament; derived

Neotectonic movements can cause severe hazards and are scientifically and socially relevant, e.g. for seismic hazard assessment, and utilisation of the subsurface for e.g. nuclear waste disposal sites and geothermal exploitation. In northern Germany, a presumed aseismic region, little is known about neotectonics because surface impressions are often missing; many faults are hidden beneath sediments.To improve the knowledge of the deformation related to and the timing of neotectonic activity, investigations of recently active fault zones, like the Osning Lineament (OL), are required. At the OL three historical earthquakes occurred in the past 400 years and the earthquake in 1612 damaged buildings in Bielefeld. The OL is a unique fault system compared to other faults in northern Germany. The faults of the OL reach the basement, whereas in the north of the Lower Saxony Basin most faults are decoupled from the basement by salt. Furthermore, the OL dips to the northeast and therefore the vector of the fault plane points towards the former iceload. Additionally, the OL had already been reactivated in the past, which might enhance further fault movement.An important step towards a comprehensive understanding of neotectonics at the OL, especially due to the limited availability of outcrops, is by using near-surface geophysical investigations, which have not been carried out at the OL as yet. It consists of a combined approach using high-resolution 2D P- and SH-wave reflection seismics. P-wave seismic alone can often not properly image near-surface impressions of faults due to poor shallow resolution, but this gap can be closed using SH-wave reflection seismics, which offers very high resolution, even at shallow depth. This will be combined with other geophysical methods, such as GPR, to investigate deformation features on sub-seismic scale, and sediment dating to derive the timing of fault movement.To be more precise, it needs to be determined how additional information on deformation features at depth complement the understanding of the interaction between glaciers and the pre-existing faults of the OL. This also includes the evaluation of the transferability of observations from sub-surface investigations to the surface, and if GPR provides additional benefit by closing the imaging gap between P-wave seismic, S-wave seismic, and outcrop scale. Furthermore, the local effect of fault geometry on stress distribution and fault reactivation, especially in the context of GIA needs to be investigated by, e.g. comparing the timing of fault reactivation and the known regional stress field with glacial events.The principal aims of this project are to reconstruct the neotectonic evolution of the OL (topics to covered: structural and physical analysis, historical- and paleo-earthquakes, and interaction of GIA and tectonic), and to evaluate how near-surface geophysics can contribute to neotectonic research.

新构造运动可能造成严重的危害，并具有科学和社会相关性，例如地震灾害评估，以及核废料处置场和地热开采等地下利用。在北方德国，一个假定的非活动区，对新构造运动知之甚少，因为地表印象常常缺失;许多断层隐藏在沉积物之下。为了提高对与新构造活动有关的变形和时间的认识，需要对最近活动的断层带（如Osning Lineament（OL））进行调查。在过去的400年里，OL发生了三次历史性地震，1612年的地震破坏了比勒费尔德的建筑物。与德国北方的其他断层相比，OL断层是一个独特的断层系统。OL断层到达基底，而在下萨克森盆地北部，大多数断层通过盐与基底分离。此外，OL倾向于东北，因此断层面的矢量指向前冰载。此外，OL在过去已经被重新激活，这可能会增强进一步的断层运动。一个重要的一步，全面了解新构造在OL，特别是由于有限的可用性露头，是通过使用近地表地球物理调查，尚未在OL进行。它包括一种使用高分辨率二维P波和SH波反射地震的综合方法。由于浅层分辨率差，单独的P波地震往往不能正确地对断层的近地表印象进行成像，但可以使用SH波反射地震来弥补这一差距，即使在浅层也能提供非常高的分辨率。这将与其他地球物理方法相结合，如探地雷达，以调查亚地震尺度上的变形特征，以及沉积物测年，以得出断层运动的时间。更准确地说，需要确定如何在深度变形特征的额外信息补充冰川和OL的预先存在的断层之间的相互作用的理解。这还包括评估观测结果从地下调查到地表的可转移性，以及GPR是否通过缩小P波地震、S波地震和露头尺度之间的成像差距而提供额外的好处。此外，断层几何形状对应力分布和断层再活化的局部影响，特别是在GIA的背景下，需要通过比较断层再活化的时间和已知的区域应力场与冰川事件来研究。（主题包括：结构和物理分析，历史和古地震，GIA和构造的相互作用），并评估近地表地球物理学如何有助于新构造研究。