Impact of Coseismic Frictional Melting on Particle Size, Shape Distribution and Chemistry of Experimentally-Generated Pseudotachylite

Publikationstyp:
Zeitschriftenaufsatz
Metadaten:
Autoren
  • Leny Montheil
  • Virginia G Toy
  • James M Scott
  • Thomas M Mitchell
  • David P Dobson
Autoren-URL
https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=fis-test-1&SrcAuth=WosAPI&KeyUT=WOS:000603051700001&DestLinkType=FullRecord&DestApp=WOS_CPL
DOI
10.3389/feart.2020.596116
eISSN
2296-6463
Externe Identifier
  • Clarivate Analytics Document Solution ID: PL3UR
Zeitschrift
FRONTIERS IN EARTH SCIENCE
Schlüsselwörter
  • frictional melting
  • experimental pseudotachylite
  • size and shape distribution
  • chemistry
  • tonalite
  • granite
Artikelnummer
ARTN 596116
Datum der Veröffentlichung
2020
Status
Published
Titel
Impact of Coseismic Frictional Melting on Particle Size, Shape Distribution and Chemistry of Experimentally-Generated Pseudotachylite
Sub types
  • Article
Ausgabe der Zeitschrift
8

Datenquelle: Web of Science (Lite)

Andere Metadatenquellen:
Abstract
<jats:p>In natural friction melts, or pseudotachylites, clast textures and glass compositions can influence the frictional behavior of faults hosting pseudotachylites, and are, in turn, sensitive to the processes involved in pseudotachylite formation. Quantification of these parameters in situations where the host rock composition and formation conditions are well-constrained, such as analogue experiments, may yield calibrations that can be employed in analysis of natural pseudotachylites. In this paper, we experimentally-generated pseudotachylites in granitoid rocks (tonalite and Westerly granite) at P<jats:sub>conf</jats:sub>= 40 MPa and slip rates of ∼0.1 m s<jats:sup>−1</jats:sup>, comparable to the conditions under which natural pseudotachylite is known to form in Earth’s upper crust. We find variations in both clast textures and glass compositions that reflect formation processes, and probably influence the frictional behavior of similar natural faults hosting pseudotachylite. Quantification of particle size and shape distribution with a semi-automatic image analysis method, combined with analysis of glass and host-rock composition of these experimentally generated pseudotachylites, reveals that the textures of pseudotachylite material evolved by combinations of 1) comminution, 2) heterogeneous frictional flash melting, and 3) homogeneous (diffusive) clast melting and/or marginal decrepitation. Fractal dimensions of pseudotachylite-hosted clasts (D ∼ 3) that are greater than those of marginal fragmented host rock particles (gouge, D ∼ 2.4), reflect an increase of the intensity of comminution by slip localisation during a pre-melting phase. Chemical analyses demonstrate that these pseudotachylite glasses were generated by frictional flash melting, where host rock phases melt individually. Biotite is the least resistant to melting, feldspar intermediate, and quartz is the most resistant. The peudotachylite glass generated in these experiments has an alkaline composition, is depleted in SiO<jats:sub>2</jats:sub>compared to the bulk host-rock, and shows heterogeneous compositions in a single sample related to proximity to host-rock minerals. The percentage contributions of host rock phases to the melt, calculated by a mixing model, shows that glass compositions are dominated by plagioclase and biotite. Within the melt, margins of clasts were dissolved uniformly by diffusion and/or affected by marginal decrepitation, resulting in convex and round shapes with convexities averaging ∼0.8 and circularities averaging ∼0.65.</jats:p>
Autoren
  • Leny Montheil
  • Virginia G Toy
  • James M Scott
  • Thomas M Mitchell
  • David P Dobson
DOI
10.3389/feart.2020.596116
eISSN
2296-6463
Zeitschrift
Frontiers in Earth Science
Online publication date
2020
Status
Published online
Herausgeber
Frontiers Media SA
Herausgeber URL
http://dx.doi.org/10.3389/feart.2020.596116
Datum der Datenerfassung
2022
Titel
Impact of Coseismic Frictional Melting on Particle Size, Shape Distribution and Chemistry of Experimentally-Generated Pseudotachylite
Ausgabe der Zeitschrift
8

Datenquelle: Crossref

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