The Brenner base tunnel (BBT) natural laboratory – From cross-section construction over fabric and elastic anisotropy analysis to 4D structural modeling

布伦纳基线隧道 (BBT) 自然实验室 â 从织物横截面构造和弹性各向异性分析到 4D 结构建模

• 批准号: 442591753
• 负责人: Dr. Christian Brandes
• 金额: --
• 依托单位: Institut für Geologie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/442591753?language=en
• 关键词: Brenner; base; tunnel; BBT; natural

The railway tunnel in the Brenner pass area (Brenner Basistunnel, BBT), which is currently under construction and is planned to reach a total length of 64 km, provides a unique geological view into the Eastern Alps. The tunnel transect crosses the western side of the antiformal nappe stack of the Tauern window including Austroalpine, Penninic, and Sub-Penninic units as well as basement of the Southern Alps. Hence, this transect covers most of the major tectonic units of the Eastern Alps, approximately 25 km west of the TRANSALP seismic cross section. To better understand the tectonic architecture and development, and to correlate the upper crustal structure with geophysical imaging results, we plan to combine geological surface information, seismic, petrophysical, microstructural and geochronological data, as well as tectonic modeling, using the software 3D MOVE.The BBT offers the unique possibility to get subsurface information of a very long cross section, including the opportunity to investigate carefully the available drill cores that cover most of the BBT transect. Drill core scanning and description will be combined with microfabric studies that apply neutron diffraction texture analysis and Vp/Vs-anisotropy modeling. The structural data provide information about strain localization as well as fault and shear zone formation in this long crustal section, which cannot be done by surface investigation in any close by resolution. Additional geological mapping and tunnel data compilation allows to construct the geological cross-section in the highest detail. Based on current tectonic models of the exhumation of the Western Tauern window, the activity of related fault zones in the area can be tested using 3D MOVE. A detailed analysis of all the major structures, correlation between the surface and the tunnel, and 2D-, 3D-modeling may help to identify crucial structures that may or may not indicate changing tectonic transport directions due to a subduction polarity change. Microfabrics and petrophysical data and especially the elastic anisotropy results from the drill core scanning and logging as well as from the texture modeling and the triaxial experiments, will be included in the cross section construction and the modeling with 3D MOVE. Based on our modeling and our laboratory data and the available time constraints we finally intend to image the patterns of our structural, microstructural and petrophysical parameters of the upper crustal BBT section in both, space and time. Furthermore, our elastic anisotropy results can be implemented into the processing of the seismic data and other deep sounding imaging techniques collected in the framework of the SPP 4D-MB and the entire AlpArray project. In that we also contribute to the interpretation of the deeper crustal investigation that focus on the anatomy of the lithosphere and any indication of a reversal in subduction polarity in the western Tauern area.

布伦纳山口地区的铁路隧道（Brenner Basistunnel，BBT）目前正在建设中，计划总长64公里，为东阿尔卑斯山脉提供独特的地质景观。隧道横断面穿过Tauern窗口的反形式推覆体堆叠的西侧，包括Austroalpine、Penninic和Sub-Penninic单元以及南阿尔卑斯山的基底。因此，该断面覆盖了东阿尔卑斯山的大部分主要构造单元，位于TRANSALP地震断面以西约25公里处。为了更好地了解构造结构和发展，并将上地壳结构与地球物理成像结果相关联，我们计划使用3D MOVE软件将地质表面信息，地震，岩石物理，显微构造和年代学数据以及构造建模相结合。BBT提供了获得非常长横截面的地下信息的独特可能性，包括有机会仔细调查覆盖大部分BBT样带的可用岩心。岩心扫描和描述将与应用中子衍射纹理分析和Vp/Vs各向异性建模的微组构研究相结合。结构数据提供了关于应变局部化以及断层和剪切带形成的信息，这些信息在这个长的地壳剖面中无法通过任何近距离分辨率的地表调查来完成。额外的地质测绘和隧道数据汇编允许构建最详细的地质横截面。根据目前的构造模型的折返的西部陶尔恩窗口，在该地区的相关断裂带的活动性，可以测试使用3D MOVE。 对所有主要构造的详细分析、地表和隧道之间的相关性以及2D、3D建模可能有助于识别关键构造，这些构造可能或可能不指示由于俯冲极性变化而导致的构造运输方向的变化。显微组构和岩石物理数据，特别是来自岩心扫描和测井以及来自纹理建模和三轴实验的弹性各向异性结果，将被包括在横截面构造和3D MOVE建模中。基于我们的建模和实验室数据以及可用的时间限制，我们最终打算在空间和时间上对上地壳BBT剖面的结构、显微结构和岩石物理参数的模式进行成像。此外，我们的弹性各向异性的结果可以实施到处理的地震数据和其他深探测成像技术中收集的SPP 4D-MB和整个AlpArray项目的框架。在这方面，我们也有助于解释更深层次的地壳调查，重点是岩石圈的解剖和任何迹象的俯冲极性反转在西部陶恩地区。