Applying scattered wave tomography and joint inversion of high-density (SWATH D) geophysical and petrophysical datasets to unravel Eastern Alpine crustal structure

应用散射波层析成像和高密度 (SWATH D) 地球物理和岩石物理数据集的联合反演来揭示东高山地壳结构

• 批准号: 442515866
• 负责人: Professor Dr. Wolfgang Friederich
• 金额: --
• 依托单位: Institut für Geologische Wissenschaften
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2020
• 资助国家: 德国
• 起止时间: 2019-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/442515866?language=en
• 关键词: Applying; scattered; wave; tomography; joint

This project harnesses the high density of seismic stations in the AlpArray complementary experiment SWATH D, conducted during the first phase of the SPP 2017 “Mountain Building Processes in 4D”, and also incorporates the wide transects EASI and the older TRANSALP, in order to understand how the crustal structure of the Alps seen today reflects the dramatic changes in mountain building style and reorganisation of plate boundaries at about 20 Ma. Uniform SE-directed subduction of European lithosphere during the Paleogene gave way to a more complex system involving not only the (partial) continuation of European subduction but the onset of Adriatic subduction below the Carpathians, the Apennines, and possibly the Alps. On the surface this revolution was reflected by laterally migrating subsidence patterns and infill in foreland basins as well as the development of different styles of accommodating shortening across the orogen. Within the crust, these changes must be accommodated by large scale decoupling horizons, but their geometry and relation to the structures seen at the surface, and even whether they are inside the crust or at the Moho, is disputed and probably differs laterally along the strike direction of the orogen. A still unresolved question concerns the existence of a possible polarity flip in the sense of subduction between the Central and Eastern Alps. If part of the continental crust is subducted, a characteristic jump in the Moho is expected, while a detachment at the base of the crust would lead to a kink in Moho topography. With this proposal we are directly addressing Theme 1 "Reorganisations of the lithosphere during mountain building" with a clear focus on mapping the possible reorganisations within the crust and of the topography of the Moho. We address Theme 2 "Surface and crustal responses" indirectly by constraining the different scenarios of crustal evolution that could have led to the current structure, and thereby provide a guide to those groups studying processes directly observable at the surface. By including experts in both seismological analysis as well as Alpine geology and petrophysics of the continental crust, we aim to go beyond merely delivering images of seismic properties by associating lithology. This proposal is part of a group of proposals with complementary goals and approaches devoted to understanding the Neogene Orogenic Revolution of the Alps.The project is structured into two work packages: The first focuses on the waveform inversion of high-frequency scattered and converted waves to image small-scale heterogeneities and discontinuities in the crust. The second employs a joint inversion of receiver functions and surface wave dispersion data using fully probabilistic Bayesian techniques. Constraints from geology and petrology will be used already at the model inference stage, not just at the interpretation stage, to best exploit the seismological data in the light of available prior knowledge.

该项目利用了在SPP 2017“4D造山过程”第一阶段进行的AlpArray补充实验SWATH D中的高密度地震台站，还结合了宽断面EASI和旧的TRANSALP，为了了解今天所看到的阿尔卑斯山的地壳结构如何反映了山脉建筑风格的巨大变化和板块边界的重组，大约20 Ma。在古近纪，欧洲岩石圈的统一SE方向俯冲让位于一个更复杂的系统，不仅涉及欧洲俯冲的（部分）延续，而且还涉及亚得里亚海俯冲到喀尔巴阡山脉、亚平宁山脉和阿尔卑斯山以下的开始。从表面上看，这场革命反映在前陆盆地的侧向迁移沉降模式和充填，以及造山带上不同类型的适应性缩短的发展。在地壳内部，这些变化必须由大尺度的退耦层来适应，但是它们的几何形状以及与地表所见结构的关系，甚至它们是在地壳内部还是在莫霍面，都是有争议的，而且可能沿造山带走向沿着横向不同。一个尚未解决的问题是，在阿尔卑斯山中部和东部之间的俯冲意义上，可能存在极性翻转。如果部分大陆地壳俯冲，莫霍面将出现特征性的跳跃，而地壳底部的拆离将导致莫霍面地形的扭折。有了这个建议，我们直接解决主题1“造山过程中岩石圈的重组”，明确重点是绘制地壳内可能的重组和莫霍面的地形。我们解决主题2“表面和地壳的反应”间接限制可能导致当前结构的地壳演化的不同情景，从而为那些研究直接在表面可观察到的过程的团体提供指导。通过包括地震学分析以及阿尔卑斯山地质学和大陆地壳岩石物理学方面的专家，我们的目标不仅仅是通过关联岩性来提供地震特性的图像。该提案是一组旨在了解阿尔卑斯山新近纪造山运动的互补目标和方法的提案的一部分，该项目分为两个工作包：第一个工作包侧重于高频散射波和转换波的波形反演，以便对地壳中的小尺度不均匀性和不连续性进行成像。第二个采用联合反演的接收器功能和面波频散数据，使用完全概率贝叶斯技术。地质学和岩石学的限制将在模型推断阶段使用，而不仅仅是在解释阶段，以便根据现有的先验知识最好地利用地震数据。