Pseudotachylyte in muscovite-bearing quartzite: Coseismic friction-induced melting and plastic deformation of quartz

Journal article


Publication Details

Author(s): Bestmann M, Pennacchioni G, Frank G, Göken M, de Wall H
Journal: Journal of Structural Geology
Publication year: 2011
Volume: 33
Journal issue: 2
Pages range: 169-186
ISSN: 0191-8141


Abstract

Thin (0.5--2~mm thick) pseudotachylyte veins occur within muscovite-bearing (~10% volume), amphibolite-facies quartzites of the Schneeberg Normal Fault Zone (Austroalpine, Southern Tyrol, Italy). Pseudotachylytes are associated with precursor localized plastic microshear zones (50--150~\textgreekmm thick) developed sub-parallel to the host-rock foliation and with conjugate sets oriented at a high angle to the foliation. Such microshear zones are characterized by recrystallization to ultrafine-grained (1--2~\textgreekmm grain size) mosaic aggregates of quartz showing a transition from a host-controlled to a random crystallographic preferred orientation towards the shear zone interior. Subsequent coseismic slip mainly exploited these microshear zones. Microstructural analysis provides evidence of extensive friction-induced melting of the muscovite-bearing quartzite, producing a bimodal melt composition. First, the host-rock muscovite was completely melted and subsequently crystallized, mainly as K-feldspar. Then, about 60% volume of the ultrafine-grained quartz underwent melting and crystallized as spherulitic rims (mostly consisting of quartz~$±$~Ti~$±$~Fe) around melt-corroded quartz clasts. The two melts show immiscibility structures in the major injection veins exploiting microshear zones at high angles to the quartzite foliation. In contrast, they were mechanically mixed during flow along the main fault veins.


FAU Authors / FAU Editors

Bestmann, Michel Dr.
Professur für Tektonik
de Wall, Helga Prof. Dr.
Professur für Tektonik
Frank, Gerhard Dr.
Lehrstuhl für Werkstoffwissenschaften (Biomaterialien)
Göken, Mathias Prof. Dr.
Lehrstuhl für Werkstoffwissenschaften (Allgemeine Werkstoffeigenschaften)


Additional Organisation
Exzellenz-Cluster Engineering of Advanced Materials


External institutions with authors

University of Padua / Universita degli Studi di Padova


Research Fields

A2 Nanoanalysis and Microscopy
Exzellenz-Cluster Engineering of Advanced Materials


How to cite

APA:
Bestmann, M., Pennacchioni, G., Frank, G., Göken, M., & de Wall, H. (2011). Pseudotachylyte in muscovite-bearing quartzite: Coseismic friction-induced melting and plastic deformation of quartz. Journal of Structural Geology, 33(2), 169-186. https://dx.doi.org/10.1016/j.jsg.2010.10.009

MLA:
Bestmann, Michel, et al. "Pseudotachylyte in muscovite-bearing quartzite: Coseismic friction-induced melting and plastic deformation of quartz." Journal of Structural Geology 33.2 (2011): 169-186.

BibTeX: 

Last updated on 2019-14-03 at 11:01