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The role of Polymineralic Rocks in the Evolution of Shear Zones

English title The role of Polymineralic Rocks in the Evolution of Shear Zones
Applicant Herwegh-Züger Marco
Number 126560
Funding scheme Project funding (Div. I-III)
Research institution Institut für Geologie Universität Bern
Institution of higher education University of Berne - BE
Main discipline Geology
Start/End 01.12.2009 - 30.11.2013
Approved amount 222'475.00
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Keywords (8)

shear zones; rock deformation; polymineralic microfabrics; quartz; olivine; mylonites; polymineralic; ebsd

Lay Summary (English)

Lead
Lay summary
Deformation in the earth's crust and upper mantle is strongly localized in, rheologically weak, large-scale shear zones, which act as important geodynamic anisotropies in extensional and compressional tectonic regimes. In order to better understand the strain localization behavior in the associated polymineralic fault rocks as a function of variable physico-chemical conditions, we investigate different natural large-scale crustal (Part A: olivine-rich) and mantle (Part B: quartz-rich) shear zones in combination with numerical modeling (Part C). Based on quantitative microstructural analyses (SEM, EBSD, CIP, EMPA), the effect of variations in the mineral content on the deformation of a dominant matrix phase is studied in terms of deformation mechanisms and rheology, as well as their changes in space and time. As an important new innovation, we are capable to transfer recently developed concepts for the mathematical description of microfabric evolution in polymineralic calcite mylonites to the olivine- and quartz-rich systems. Based on the link between micro-, meso- and large-scale structures, inferences on the evolution of the strain localization behavior will be obtained. In combination with geophysical parameters (rheology, seismic anisotropies etc.) the new data will allow improved predictions on the distribution of deformation at depths, which is of great interest in different disciplines of earth sciences such as structural geology, tectonics, petrology, rock mechanics, geophysics and geodynamics.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Mechanical anisotropy control on strain localization in upper mantle shear zones
Herwegh Marco, Mercolli Ivan, Linckens Jolien, Müntener Othmar (2016), Mechanical anisotropy control on strain localization in upper mantle shear zones, in Tectonics, 35, 1177-1204.
Small quantity but large effect — How minor phases control strain localization in upper mantle shear zones
Linckens Jolien, Herwegh Marco, Müntener Othmar (2015), Small quantity but large effect — How minor phases control strain localization in upper mantle shear zones, in Tectonophysics, 643, 26-43.
Microfabric memory of vein quartz for strain localization in detachment faults: A case study on the Simplon fault zone
Haertel Mike, Herwegh Marco (2014), Microfabric memory of vein quartz for strain localization in detachment faults: A case study on the Simplon fault zone, in Journal of Structural Geology, 68, 16-32.
Titanium-in-quartz thermometry on synkinematic quartz veins in a retrograde crustal-scale normal fault zone
Haertel Mike, Herwegh Marco, Pettke Thomas (2013), Titanium-in-quartz thermometry on synkinematic quartz veins in a retrograde crustal-scale normal fault zone, in Tectonophysics, 608, 468-481.
Evolution of a polymineralic mantle shear zone and the role of second phases in the localization of deformation
Linckens J, Herwegh M, Muntener O, Mercolli I (2011), Evolution of a polymineralic mantle shear zone and the role of second phases in the localization of deformation, in JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 116, 1728-1750.
Linking temperature estimates and microstructures in deformed polymineralic mantle rocks
Linckens J, Herwegh M, Muntener O (2011), Linking temperature estimates and microstructures in deformed polymineralic mantle rocks, in GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS, 12(8), 1-19.
The role of second phases for controlling microstructural evolution in polymineralic rocks: A review
Herwegh Marco, Linckens J., Ebert A., Berger A., Brodhag S.H. (2011), The role of second phases for controlling microstructural evolution in polymineralic rocks: A review, in Journal of Structural Geology, 33, 1728-1750.
From transient to steady state deformation and grain size: A thermodynamic approach using elasto-visco-plastic numerical modeling
Herwegh Marco, Poulet Thomas, Karrech Ali, Regenauer-Lieb Klaus, From transient to steady state deformation and grain size: A thermodynamic approach using elasto-visco-plastic numerical modeling, in Journal of Geophysical Research.

Collaboration

Group / person Country
Types of collaboration
University of Lausanne Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
University of Western Australia Australia (Oceania)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure
University Frankfurt Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Australian Ressources and Research Centre Australia (Oceania)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Alpine Workshop (Emile Argand Conference) Talk given at a conference Strain localization history of the Simplon Fault Zone: How far can we look back? 10.09.2013 Schladmin, Austria Herwegh-Züger Marco; Härtel Mike;
Physical Properties and Dating of Fault Rocks Individual talk Strain localization in large-scale shear zones and related microstructures 03.10.2012 ETHZ, Switzerland Linckens Jolien; Herwegh-Züger Marco;
EGU 2012 Talk given at a conference The role of second phases for controlling microstructural evolution in polymineralic rocks 23.04.2012 Vienna, Austria Linckens Jolien; Herwegh-Züger Marco;
TSK workshop Individual talk Workshop on deformation of polymineralic rocks in nature and experiment 26.03.2012 Kiel, Germany Herwegh-Züger Marco;
Swiss Geoscience Meeting Talk given at a conference Ti in quartz geothermometry in mylonites of the Simplon fault zone. What can we learn? 19.11.2011 ETHZ, Switzerland Herwegh-Züger Marco; Härtel Mike;
Deformation, Rheology and Tectonics (visited by Mike Härtel) Talk given at a conference Linking titanium-in-quartz thermometry and quartz microstructures: strong evidence of continued vein formation during strain localization 01.09.2011 Oviedo, Spain, Spain Herwegh-Züger Marco; Härtel Mike;
EGU 2010 Talk given at a conference Generalization of the microstructural evolution in polymineralic mantle shear zones: an attempt of a grain size evolution map 02.04.2010 Vienna, Austria, Austria Herwegh-Züger Marco; Linckens Jolien; Müntener Othmar;


Self-organised

Title Date Place
Swiss Tectonics Studies Group Excursion 19.08.2011 Engelberg, Grimsel, Switzerland

Awards

Title Year
Fachpreis Geowissenschaften 2011

Associated projects

Number Title Start Funding scheme
109369 Rasterelektronenmikroskop Geologie Bern 01.02.2006 Project funding (Div. I-III)
66889 Grain growth in polyphase rocks under static and deformational conditions in nature and experiment 01.04.2002 Project funding (Div. I-III)
132196 Structure and evolution of an antiformal nappe stack (Aar massif, Central Alps): Formation of mechanical anisotropies and their bearing on natural risks 01.10.2010 Project funding (Div. I-III)
113563 Die Rolle polymineralischer Mylonite bei der Ausbildung von Scherzonen 01.12.2006 Project funding (Div. I-III)
113563 Die Rolle polymineralischer Mylonite bei der Ausbildung von Scherzonen 01.12.2006 Project funding (Div. I-III)
149385 Structure and evolution of an antiformal nappe stack (Aar massif, Central Alps): Formation of mechanical anisotropies and their bearing on natural risks 01.10.2013 Project funding (Div. I-III)
169055 Structure and evolution of an antiformal nappe stack (Aar massif, Central Alps): Formation of mechanical anisotropies and their bearing on natural risks 01.10.2016 Project funding (Div. I-III)

Abstract

With this proposal we ask for a three years prolongation of the currently running SNF project 'the role of polymineralic rocks in the evolution of shear zones' (200021-113563). Deformation in the earth's crust and upper mantle is strongly localized in, rheologically weak, large-scale shear zones, which act as important geodynamic anisotropies in extensional and compressional tectonic regimes. In order to better understand the strain localization behavior in the associated polymineralic fault rocks as a function of variable physico-chemical conditions, we investigate different natural large-scale crustal (Part A: olivine-rich) and mantle (Part B: quartz-rich) shear zones in combination with numerical modeling (Part C). Based on quantitative microstructural analyses (SEM, EBSD, CIP, EMPA), the effect of variations in the mineral content on the deformation of a dominant matrix phase is studied in terms of deformation mechanisms and rheology, as well as their changes in space and time. As an important new innovation, we are capable to transfer recently developed concepts for the mathematical description of microfabric evolution in polymineralic calcite mylonites to the olivine- and quartz-rich systems. Based on the link between micro-, meso- and large-scale structures, inferences on the evolution of the strain localization behavior will be obtained. In combination with geophysical parameters (rheology, seismic anisotropies etc.) the new data will allow improved predictions on the distribution of deformation at depths, which is of great interest in different disciplines of earth sciences such as structural geology, tectonics, petrology, rock mechanics, geophysics and geodynamics.The project benefits from national (ETHZ, Uni Lausanne, Uni Basel) and international collaborations with leading scientists from Australia, Germany and the US.
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