Seismically induced kinking in quartz

Bestmann, Michel, Grasemann, Bernhard, Kilian, Rudiger, Wheeler, John ORCID: 0000-0002-7576-4465, Morales, Luiz FG, Bezold, Andreas and Pennacchioni, Giorgio (2025) Seismically induced kinking in quartz EARTH AND PLANETARY SCIENCE LETTERS, 670. 119546-. ISSN 0012-821X, 1385-013X

Text ms_Bestmann et al_EPSL_revised_inklFig__2025-06-17_final.docx - Author Accepted Manuscript Available under License Creative Commons Attribution. Download (5MB)

Abstract

Deformed quartz veins next (1–1.5 m) to an exhumed pseudotachylyte-bearing (i.e. anciently seismic) fault within the Schobergruppe (Austroalpine Crystalline Complex, Eastern Alps) contain intensely kinked quartz grains. The monoclinic symmetry of kink bands is consistent with the dextral slip sense of the fault. Cathodoluminescence images show a very high density of intragranular, sub-planar, lamellae accompanied by nanometre-scale fluid-related porosity visible in electron backscatter orientation contrast. Based on the oscillating orientation variation across subgrain boundaries (misorientation angle 1–9°) these lamellae (oriented (sub)parallel to a rhomb plane and spaced 4–10 µm apart) are identified as short-wavelength undulatory extinction microstructures (SWUE). Transmission electron microscopy reveals a high degree of recovery (low dislocation density) across the SWUE. Only grains with SWUE oriented parallel to the vein boundary are kinked. Based on detailed microstructural and crystallographic analysis, we infer the following history of kinking evolution related to the seismic cycle: (I) Deformation lamellae formed at high differential stresses preceding, or associated with, seismic rupture propagation. The initial high dislocation density within deformation lamellae provided the mechanical anisotropy in quartz required for (II) the subsequent coseismic initiation of kinking. The lamellae acted as a geometric filter that only allowed r < a> slip of dislocations parallel to the lamellae. These athermal dislocations were able to glide fast over a relatively large distance before piling up and initiating kinking during the coseismic event. Progressive build-up of dislocations resulted in deformation bands which accumulated the final misorientation angle between host domain and kink domain. (III) Residual stress during post-seismic deformation induced dynamic re-arrangement of dislocations into sub-parallel subgrain boundaries which now characterize the kink band boundary region. We suggest that kinking in quartz potentially indicates coseismic deformation and is an important mechanism for incipient strain accommodation during high strain rates.

Item Type:	Article
Uncontrolled Keywords:	Quartz, Kinking, Seismic, Athermal dislocation, Anisotropy, Weighted burgers vector
Divisions:	Faculty of Science & Engineering Faculty of Science & Engineering > School of Environmental Sciences Faculty of Science & Engineering > School of Environmental Sciences > Earth, Ocean and Ecological Sciences
Depositing User:	Symplectic Admin
Date Deposited:	11 Dec 2025 10:46
Last Modified:	16 Jun 2026 20:02
DOI:	10.1016/j.epsl.2025.119546
Related Websites:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3196083
Disclaimer:	The University of Liverpool is not responsible for content contained on other websites from links within repository metadata. Please contact us if you notice anything that appears incorrect or inappropriate.