quartz; natural risk; nappe stack; deformation mechanisms; exhumation history; 3D; rock deformation; strain localization; seismicity
Berger Alfons, Engi Martin, Erne-Schmid Silja, Glotzbach Christoph, Spiegel Cornelia, de Goede Rick, Herwegh Marco (2020), The relation between peak metamorphic temperatures and subsequent cooling during continent–continent collision (western Central Alps, Switzerland), in Swiss Journal of Geosciences
, 113(1), 4-4.
Herwegh M., Berger A., Glotzbach C., Wangenheim C., Mock S., Wehrens P., Baumberger R., Egli D., Kissling E. (2020), Late stages of continent-continent collision: Timing, kinematic evolution, and exhumation of the Northern rim (Aar Massif) of the Alps, in Earth-Science Reviews
, 200, 102959-102959.
Nibourel Lukas, Berger Alfons, Egli Daniel, Luensdorf Nils K., Herwegh Marco (2018), Large vertical displacements of a crystalline massif recorded by Raman thermometry, in Geology
, 46(10), 879-882.
In the current proposal we are asking for the second prolongation for a duration of 27 months. The past three years of the project can be divided in a first part, during which the PhD theses of R. Baumberger (PhD A) and P. Wehrens (PhD B) were terminated in spring 2015 and a second part, the start of a succeeding PhD thesis of L. Nibourel (PhD D). The PhD thesis of T. Buckingham (PhD C) will not be part of this proposal. PhD A and B focused their studies on the Central Aar massif (Haslital). PhD A successfully developed a workflow for (i) the area-wide consistent mapping of lineaments, (ii) unraveled the link between tectonic pre-conditioning and today’s morphological surface incisions and (iii) designed a workflow to use surface information of shear zones for the prediction of their continuation at depth in 3D models incorporating associated uncertainties. PhD B mainly dealt with the structo-mechanical evolution of the Aar massif. In this way, (iv) the kinematic evolution and deformation stages for the Grimsel region were established, (v) the interplay between brittle and ductile processes during mid-crustal deformation was unraveled and (vi) K-Ar dating was applied to obtain age constraints on the timing of the different deformation processes/episodes. Additionally, (vii) E. Kissling, A. Berger and M. Herwegh developed a geodynamic model for the evolution of the Aar massif connecting mantle processes with physical responses in the crust and (viii) A. Berger and M. Herwegh investigated the role of the geometry of the former European passive continental margin on the inversion during Alpine orogeny. Along (i-viii) papers are either in the revision stage or close to submission. PhD student D started early 2015 and carried out extensive fieldwork and sampling campaigns in the Reuss valley region (Eastern Aar massif) and is currently working on data analysis and sample preparation. In the current proposal we are asking for a final extension of the current project for a duration of 27 months (fin de thèse of L. Nibourel). During this project period L. Nibourel will focus on three main tasks: (i) the structural and kinematic evolution of the Eastern Aar massif, (ii) the unraveling of the metamorphic and exhumation history and (iii) the link to recent seismic activity. For this purpose, different geothermometers and thermochronometers will be applied on the collected samples (i.e. Raman spectroscopy, U+Th/He in zircon) and accomplished by literature data (fission track data from zircon and apatite). Moreover, in close collaboration with the Schweizerischer Erdbebendienst (SED; T. Diehl and E. Kissling ETHZ) seismically active domains will be analysed and connected to fault structures explored in the field. Combining information on the spatial distribution of fault structures, their evolution and propagation in time and the sites of today’s seismic activity will provide new information on the deformation behavior in the middle to upper crust. This will be an important prerequisite to link the structural information with seismic hazard analysis. To close the gap, a last field campaign in summer 2017 will be necessary. In light of the Aar massif being the largest external massif of the Swiss Alps, M. Herwegh, A. Berger and E. Kissling will expand their investigations on the link between mantle processes and crustal response towards 3D combining different sections of surface/subsurface tectonics with seismic tomography. A comprehensive 3D model will be generated allowing deep insights into the evolution of the backbone of the Alps.