Identifying Main Lithospheric Structures in the Eastern Alpine Domain by Joint Inversion of Receiver Function and Surface Wave Measurements for Seismic Anisotropy

阿尔卑斯山脉的造山活动始于新近纪，当时源自欧亚大陆的地壳单元、过渡性洋盆和微大陆受到接近的亚得里亚海板块的强烈变形和褶皱。东阿尔卑斯山脉非常适合研究包括地壳剥离和变形、推覆体堆积和侧向逃逸在内的完整的造山复杂性。然而，由于东阿尔卑斯地区的地壳和深部岩石圈结构仍然没有得到很好的解决，其潜在的过程，特别是驱动力仍然是一个谜。了解东阿尔卑斯新近纪以来的造山过程的先决条件是确定缝合线以北侧向逸出的内层和解耦层的形状，并澄清深层岩石圈结构。无论是亚德里亚还是欧亚大陆是上板块，还是造山活动是双向俯冲的结果，这仍然是一个悬而未决的问题。此外，地幔岩石圈的性质也需要解决，因为它们是量化导致碰撞和造山的构造力的关键。AlpArray是有史以来同时部署的最密集的区域地震阵列，为详细研究造山带深部岩石圈结构提供了独特的机会。东阿尔卑斯山的完整数据集将于2021年提供。在SPP第一阶段的不同项目中进行的表面波和接收函数测量的基础上，我们将对数据进行联合反演，从而得到岩石圈的高分辨率剪切波速度模型，以解决绝对剪切波速度和主要的地壳和地幔不连续面。我们将扩展随机反演方案，以获得各向同性和各向异性模型及其不确定性。由此产生的高分辨率模型将产生阿尔卑斯东部岩石圈的地震模型。将其与地表地质记录相结合，识别出主要深部构造的构造亲和性。我们将以地震观测为基础，围绕“造山过程中岩石圈的重组”这一研究主题，与合作伙伴共同开发新近纪以来东阿尔卑斯岩石圈构造演化的4D综合模型。这将为造山数值地球动力学模拟提供依据。

Mountain building in the Alps started in the Neogene when crustal units derived from Eurasia, inter-vening oceanic basins and microcontinents got strongly deformed and folded by the approaching Adriatic intender. The eastern Alps are ideally suited to study the full complexity of mountain building including crustal delamination and deformation, nappe stacking and lateral escape. The underlying processes and in particular the driving forces remain enigmatic, however, because the crustal and deep lithospheric structure in the eastern Alpine domain are still poorly resolved. A pre-requisite for the understanding of mountain building processes since the Neogene in the eastern Alps is the identification of the shape of the intender and of the decoupling horizon for the lateral escape north of the suture as well as the clarification of the deep lithospheric structure. It re-mains an open question if Adria or Eurasia are the upper plate or if mountain building is the result of bivergent subduction. Also, properties of the mantle lithosphere need to be resolved as they are key for the quantification of tectonic forces causing collision and mountain building. AlpArray – the densest regional seismic array ever deployed contemporaneously - provides a unique opportunity to study the deep lithospheric structure of the orogen in detail. The complete data set for the eastern Alps will be available in 2021. Building on surface-wave and receiver-function measure-ments carried out in separate projects in the first phase of the SPP, we will perform a joint inver-sion of the data that will result in a high-resolution, shear-wave velocity model of the lithosphere to resolve both the absolute shear-wave velocity and major crust and mantle discontinuities. We will extend stochastic inversion schemes to obtain isotropic and anisotropic models and their uncertain-ties. The resulting high-resolution model will yield a seismic model for the eastern Alpine litho-sphere. Relating it to the geological record at the surface, the tectonic affinity of the main deep structures will be identified. Based on seismological observations, we will develop together with co-operation partners focusing on the research theme “Reorganizations of the lithosphere during moun-tain building” a 4D comprehensive model of the tectonic evolution of the lithosphere in the eastern Alps since the beginning of the Neogene. It will provide the basis for numerical geodynamic modelling of mountain building.