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Microstructures in Quartz: Indicators for Kinematics and the Conditions for...
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Microstructures in Quartz: Indicators for Kinematics and the Conditions for Ductile Deformation in Tectonites

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Crystallography and Physical Chemistry of Minerals & Nanominerals".

Deadline for manuscript submissions: closed (6 September 2023) | Viewed by 5440

Special Issue Editor

Prof. Dr. Toru Takeshita

E-Mail Website
Guest Editor
Professor Emeritus, The Division of Academic Resources and Specimens, The Hokkaido University Museum, Hokkaido University, Sapporo 060-0810, Japan
Interests: structural geology; tectonics; microstructure; rheology; deformation bands; landslide
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Microstructures in quartz, which are one of the principal constituents of rocks in the continental upper crust, have been extensively studied by structural geologists because they can be good indicators of kinematics and deformation conditions during orogenesis and the formation of ductile shear zones. In particular, because the pattens of quartz crystallographic orientations (CPO) can be readily obtained using electron backscatter diffraction (EBSD) techniques, research on quartz microstructures has become incredibly popular since the advent of EBSD. Further, microtectonic studies, combined with analyses of phase equilibria to infer the pressure and temperature (P–T) conditions and radiometric age dating to infer the formation and cooling ages (t) of metamorphic rocks, have recently become so useful that complete P–T–t–D (deformation) paths in rocks can now be reconstructed. With the amount of research carried out in recent years on P–T–t–D paths, it is time to summarize these achievements and draw conclusions. In particular, there has been significant disagreement in previous research regarding the formation conditions of quartz microstructures. Furthermore, since quartz microstructures are affected by not only external physical conditions such as temperature, strain rate, and water fugacity, but also material properties such as grain size and percentage of non-quartz phases in polyphase rocks, these effects must be more vigorously investigated, comparing similar research in orogenic belts and shear zones in the world.

In this Special Issue of Minerals, any contributions dealing with microstructures in deformed and recrystallized quartz grains in natural orogenic belts and shear zones, and in particular studies focusing on physical conditions for the formation of microstructures in quartz, which can be used to reconstruct P–T–t–D paths, are welcome. Further, experimental and theoretical studies on the ductile deformation and formation of microstructures in quartz, which can advance the study of estimation of physical conditions for deformation in quartz, are also welcome.

Prof. Dr. Toru Takeshita
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Minerals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • quartz
  • dynamic recrystallization
  • microstructures
  • deformation conditions
  • ductile shear zones
  • electron backscatter diffraction (EBSD)

Published Papers (2 papers)

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Research

16 pages, 3854 KiB  
Article
Steady-State Microstructures of Quartz Revisited: Evaluation of Stress States in Deformation Experiments Using a Solid-Medium Apparatus
by Ichiko Shimizu and Katsuyoshi Michibayashi
Minerals 2022, 12(3), 329; https://doi.org/10.3390/min12030329 - 06 Mar 2022
Viewed by 2166
Abstract
Dynamically recrystallizing quartz is believed to approach a steady-state microstructure, which reflects flow stress in dislocation creep. In a classic experimental study performed by Masuda and Fujimura in 1981 using a solid-medium deformation apparatus, two types of steady-state microstructures of quartz, denoted as [...] Read more.
Dynamically recrystallizing quartz is believed to approach a steady-state microstructure, which reflects flow stress in dislocation creep. In a classic experimental study performed by Masuda and Fujimura in 1981 using a solid-medium deformation apparatus, two types of steady-state microstructures of quartz, denoted as S and P, were found under varying temperature and strain rate conditions. However, the differential stresses did not systematically change with the deformation conditions, and unexpectedly high flow stresses (over 700 MPa) were recorded on some experimental runs compared with the applied confining pressure (400 MPa). Internal friction in the sample assembly is a possible cause of reported high differential stresses. Using a pyrophyllite assembly similar to that used in the previous work and setting up paired load cells above and below the sample assembly, we quantified the frictional stress acting on the sample and corrected the axial stress. The internal friction changed in a complicated manner during pressurization, heating, and axial deformation at a constant strain rate. Our results suggest that Masuda and Fujimura overestimated the differential stress by about 200 MPa in their 800 °C runs. Crystallographic fabrics in the previous experimental sample indicated that the development of elongated quartz grains, which are characteristics of Type-S microstructures, was associated with preferential growth of unfavorably oriented grains during dynamic recrystallization. Full article
(This article belongs to the Special Issue Microstructures in Quartz: Indicators for Kinematics and the Conditions for Ductile Deformation in Tectonites)
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23 pages, 4277 KiB  
Article
Quartz Microstructures from the Sambagawa Metamorphic Rocks, Southwest Japan: Indicators of Deformation Conditions during Exhumation
by Toru Takeshita
Minerals 2021, 11(10), 1038; https://doi.org/10.3390/min11101038 - 25 Sep 2021
Cited by 9 | Viewed by 2415
Abstract
The Sambagawa metamorphic rocks in central Shikoku, southwest Japan consist of an inverted metamorphic sequence from the upper chlorite to oligoclase-biotite zones at the lower structural level (LSL), which is overlain by a normal metamorphic sequence consisting of the albite-biotite and garnet zones [...] Read more.
The Sambagawa metamorphic rocks in central Shikoku, southwest Japan consist of an inverted metamorphic sequence from the upper chlorite to oligoclase-biotite zones at the lower structural level (LSL), which is overlain by a normal metamorphic sequence consisting of the albite-biotite and garnet zones at the upper structural level (USL). These sequences form a large-scale recumbent fold called the Besshi nappe. To unravel the mechanism of recrystallization and physical conditions in quartz, and their relation to exhumation tectonics, microstructures of recrystallized quartz grains in quartz schist from the Asemi-Saruta-Dozan River traverse were analyzed. The recrystallized quartz grain size increases with increasing structural level from 40 µm in the upper chlorite zone to 160 µm in the garnet zone of the USL. Further, the mechanism of dynamic recrystallization of quartz changes from subgrain rotation to grain boundary migration with increasing structural level across the uppermost garnet zone of the LSL. From these data, the deformation temperatures in quartz schist are calculated to increase with increasing structural level within the range between 300 and 450 °C using paleopiezometers and experimental flow laws. It could be interpreted that a rapid cooling of the Besshi nappe from above is responsible for the deformation temperatures recorded in quartz schist. Full article
(This article belongs to the Special Issue Microstructures in Quartz: Indicators for Kinematics and the Conditions for Ductile Deformation in Tectonites)
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