Transient deformation and long-term shear zone activity

瞬态变形和长期剪切带活动

• 批准号: 422770303
• 负责人: Professorin Dr. Claudia Trepmann
• 金额: --
• 依托单位: Department für Geo- und Umweltwissenschaften
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/422770303?language=en
• 关键词: Transient; deformation; long; term; shear

During orogeny on the time scale of Millions of years, crustal blocks are offset over kilometre-scale distances along shear zones. Transient deformation at high and then relaxing stresses in shear zones can be triggered by seismic slip events taking place on the time scale of seconds. - What is the signature of multiple seismic events in the geological record from the base of the seismogenic zone? - How can different transient high-stress deformation events in a specific rock be distinguished? - What is the role of transient deformation on the long-term shear zone activity?To address these questions we propose a field-based and micro-analytical approach on the base of the Silvretta nappe in the Central Alps. There, mutually crosscutting mylonites and pseudotachylytes are well exposed. We will analyse the deformation history that is recorded by these crosscutting relations considering deformation in dependence to the tip of a propagating seismic active fault. We will test whether they indicate (1) a specific sequence of accelerated creep followed by deformation at transiently high and then relaxing stresses, or (2) a cyclic overprinting of several high-stress deformation events. We aim at a conceptual model for the temporal and spatial scale–dependent rheology related to the distance to the tip of a propagating seismic active fault. The findings will be discussed in the light of the specific characteristics in thrust regimes and compared to those of different tectonic regimes. The findings are expected to lead to a better understanding on the role of seismic slip and related deformation at the base of the seismogenic zone on the long-term shear zone activity offsetting crustal blocks over kilometre-scale distances.

在数百万年时间尺度的造山运动期间，地壳块体沿着剪切带偏移公里尺度的距离。在数秒的时间尺度上发生的地震滑移事件可能会触发剪切带中高应力下的瞬态变形，然后松弛。 - 地质记录中来自地震带底部的多次地震事件的特征是什么？ - 如何区分特定岩石中不同的瞬态高应力变形事件？ - 瞬态变形对长期剪切带活动的作用是什么？为了解决这些问题，我们在中部阿尔卑斯山的 Silvretta 推覆体的基础上提出了一种基于现场的微观分析方法。在那里，相互交叉的糜棱岩和假速岩充分暴露。我们将分析这些横切关系记录的变形历史，考虑变形与传播的地震活动断层尖端的关系。我们将测试它们是否表明（1）加速蠕变的特定顺序，然后在瞬时高应力下变形，然后松弛，或（2）几个高应力变形事件的循环叠印。我们的目标是建立一个与传播地震活动断层尖端的距离相关的时空尺度相关流变学的概念模型。研究结果将根据逆冲区域的具体特征进行讨论，并与不同构造区域的结果进行比较。预计这些发现将有助于更好地理解地震滑动和孕震带底部的相关变形对在公里级距离上抵消地壳块的长期剪切带活动的作用。