High-resolution 3-D multi-component seismics for an improved structural, facial, and process-related characterisation of glacially overdeepened valleys and basins in the Alps

高分辨率 3-D 多分量地震可改善阿尔卑斯山冰川过深的山谷和盆地的结构、面和过程相关特征

• 批准号: 270342880
• 负责人: Dr. Hermann Buness
• 金额: --
• 依托单位: Leibniz-Institut für Angewandte Geophysik (LIAG)
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/270342880?language=en
• 关键词: resolution; multi; component; seismics; improved

The integration of high-resolution three-dimensional (3-D) and multi-component seismics for an improved structural, facial, and process-related characterization of overdeepened valleys and basins defines the principal aim and scientific-technical approach of this project. Overdeepened structures are known from formerly glaciated areas worldwide. They have important impact on both applied and basic aspects of human life and research. Highly topical issues are groundwater exploration, geohazard potential (site effects, mass movements), and geo-engineering (nuclear waste repositories, tunnelling). The sediments in overdeepened structures also provide important information about timing and extent of past glaciations. These aspects require a profound knowledge of the sediment fill and valley genesis, tackled by the ICDP initiative Drilling Overdeepened Alpine Valleys (DOVE) with boreholes to be cored at key locations in the European Alps. To create an exemplary and transferable seismic workflow for geological depth model building, a systematic reflection seismic research study will be performed in the Tannwald (Germany) and Lienz Basins (Austria) which will be representative of overdeepened structures in the Alpine foreland and the inner-Alpine area. The methodological work will especially contribute to an improved mapping of the valley shapes, a more detailed and facies-based interpretation of the sedimentary infill, the interpretation of glaciotectonic features, and the spatial and temporal process understanding of overdeepened valley development and its recent consequences. Advanced survey designs allow to derive comprehensive petrophysical parameter sets to support geological interpretation, and most importantly, not restricted to 1-D information in a borehole but with spatial extent. The limitations of classical P-wave seismics will be overcome by an innovative and combined field-acquisition and processing scheme that makes use of the development of new seismic sources designed for the exploration of near-surface structures, consolidated experience with S-wave reflection seismics, and new opportunities provided by multi-component seismics. Here, we suggest consecutive seismic surveys that use P- and S-wave sources on the one hand, combined with 3-component (3-C) receivers on the other hand. Thereby, so-called 9-C surveying is finally possible, concerted on 2-D profiles and in 3-D. This will satisfy, for the first time, the challenging demands of imaging overdeepened structures in terms of (near-surface) complexity, small rock physical contrasts, and anisotropy. Accompanying seismic modelling will contribute a deeper understanding of the nature of reflections gained and will provide insight into the wavefields characteristics to better understand the geophysical properties of overdeepened structures. A local, target-oriented multi-component 3-D survey focusing on wave-propagation effects in shallow structures will complete this systematic study.

将高分辨率三维(3-D)和多分量地震相结合，以改进过深山谷和盆地的结构、面貌和与过程有关的特征，确定了该项目的主要目标和科学技术方法。世界各地以前的冰川地区都发现了过度加深的构造。它们对人类生活和研究的应用和基本方面都有重要影响。高度热门的问题是地下水勘探、潜在的地质灾害(场地效应、质量移动)和地球工程(核废料储存库、隧道施工)。过深构造中的沉积物也提供了有关过去冰川时间和程度的重要信息。这些方面需要对沉积物充填和山谷成因有深刻的了解，ICDP倡议通过在欧洲阿尔卑斯山的关键位置钻探过深的阿尔卑斯山山谷(DOVE)来解决这一问题。为建立地质深度模型的示范和可移植的地震工作流程，将在Tannwald盆地(德国)和Lienz盆地(奥地利)进行系统的反射地震研究，这将是阿尔卑斯山前陆和阿尔卑斯山内地区过深构造的代表。这项方法学工作将特别有助于改进山谷形状的测绘，更详细和基于相的沉积充填解释，冰川构造特征的解释，以及对过度加深的山谷发育及其近期后果的空间和时间过程的了解。先进的测量设计允许获得全面的岩石物理参数集，以支持地质解释，最重要的是，不限于井筒中的一维信息，而是具有空间范围。一种创新的综合野外采集和处理方案将克服经典P波地震的局限性，该方案利用了为勘探近地表构造而设计的新震源的开发，巩固了S波反射地震的经验，以及多分量地震提供的新机遇。在这里，我们建议进行连续的地震勘探，一方面使用P波源和S波源，另一方面结合三分量(3-C)接收器。因此，所谓的9-C测量最终成为可能，在2-D剖面和3-D剖面上协调一致。这将首次满足成像过深构造在(近地表)复杂性、小岩石物理对比度和各向异性方面的挑战性要求。随之而来的地震模拟将有助于更深入地了解所获得的反射的性质，并将提供对波场特征的洞察，以更好地了解过深构造的地球物理性质。一个局部的、面向目标的多分量三维测量将完成这项系统的研究，重点是浅层结构中的波传播效应。