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.

在造山学的时间尺度上，在数百万年的时间范围内，地壳块被沿剪切带的千里尺寸距离抵消。在高高处的瞬态变形，然后在剪切带中的松弛应力是通过在秒的时间尺度上发生的地震滑移事件触发的。 - 地震区底部的地质记录中多个地震事件的签名是什么？ - 如何区分特定岩石中不同的瞬态高应力变形事件？ - 瞬态变形在长期剪切区活动中的作用是什么？解决这些问题，我们在中央阿尔卑斯山中的Silvretta Nappe底部提出了一种基于现场和微型分析方法。在那里，相互交叉的mylonites和伪thy虫的暴露良好。我们将分析这些横切关系记录的变形历史记录，以考虑变形依赖于传播的地震活动断层的尖端。我们将测试它们是否指示（1）特定的加速蠕变序列，然后在短暂的高应力下变形，然后在宽松的应力下变形，或（2）几个高应力变形事件的循环覆盖。我们旨在针对与传播地震活跃断层距离距离距离临时和空间量表依赖性流变学的概念模型。这些发现将根据推力制度中的特定特征，并将其与不同构造制度的特定特征进行讨论。预计这些发现将使人们更好地了解地震滑动和相关变形在地震区底部对长期剪切区活性的基础的作用，从而抵消了在千尺度距离上的地壳块。