Dislocation in Minerals

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Mineralogical Crystallography and Biomineralization".

Deadline for manuscript submissions: closed (20 July 2022) | Viewed by 5527

Special Issue Editors


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Guest Editor
Engineering Research Center of Nano-Geo Materials of Ministry of Education, China University of Geosciences, Wuhan 430074, China
Interests: mineral microstructure; mineral exsolution; TEM analysis; rheological experiment

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Guest Editor
Gemmology Institute, China University of Geosciences, Wuhan 430074, China
Interests: gemmology; mineral microstructure; TEM analysis
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Guest Editor
Ocean College, Hebei Agricultural University, Qinhuangdao 066000, China
Interests: mineral microstructure; mineral exsolution

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Guest Editor
Bayerisches Geoinstitut, Universität Bayreuth, Bayreuth, Germany
Interests: mineral rheology; mineral microstructure
Geosciences Department, University of Wisconsin-Parkside, Kenosha, WI 53144, USA
Interests: crystal structure of clay minerals; interactions of crystals with environmental contaminants; environmental remediations using nano materials and Earth materials
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Dislocation is a special microstructure in minerals, representing linear defects including edge, screw, or mixed dislocation types. Dislocation in minerals can act as a record of various geological processes that formed and modified rocks and other geological materials. Therefore, dislocation analysis is a powerful and essential method to study and understand the deformation, evolution, phase transition, and rheological property of minerals. These subjects have great significance in crystallography, mineralogy, microstructural geology, and geodynamics.

At present, transmission electron microscopy (TEM) is still the most effective method for high-resolution observation and precise analysis of dislocations, though it cannot be used to analyze large areas in minerals. With the development of technology, the traditional methods (e.g., oxidation decoration in olivine and etch pitting in quartz) that reveal dislocations on the crystal surface have seen great advances in recent years and now allow for more effective analyses of dislocation. X-ray diffraction topography is a well-established method to record in-situ deformation experiments on minerals by means of a stress sensor. Electron-channeling contrast imaging (ECCI) and electron backscatter diffraction (EBSD) have been successfully used to analyze the lattice-preferred orientation, dislocation slip systems and other dislocation microstructures (e.g., dislocation research on garnet and olivine). Recently, premelting decoration—a new method for revealing dislocations in garnet—has been established.

Both original research papers and review articles related to “Dislocation in minerals” are welcome contributions to this Special Issue. The potential topics include, but are not limited to:

  • Advances in methods of revealing dislocations;
  • The relationship between dislocation slip systems and lattice-preferred orientation (LPO);
  • Plastic deformation mechanisms of natural and synthetic minerals;
  • Numerical modelling of the dislocation dynamics in minerals;
  • The relationship among phase evolution, transition, twinning, exsolution and dislocation;
  • The estimation of differential stress based on dislocation density.

Prof. Dr. Xiangwen Liu
Prof. Dr. Tao Chen
Dr. Zhanjun Xie
Dr. Lin Wang
Dr. Zhaohui Li
Guest Editors

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Keywords

  • crystal defects
  • dislocation microstructures
  • dislocation decoration
  • dislocation slip systems
  • dislocation dynamics
  • lattice-preferred orientation (LPO)
  • rheological experiment
  • dislocation creep regime
  • plastic deformation
  • differential stress piezometer

Published Papers (3 papers)

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Research

14 pages, 8197 KiB  
Article
A TEM Study on a Polycrystalline Olivine Sample Deformed in a D-DIA under Mantle Conditions
by Tao Chen, Nadege Hilairet and Yanbin Wang
Crystals 2022, 12(10), 1396; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12101396 - 02 Oct 2022
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Abstract
We carried out an electron microscopy study on a polycrystalline olivine sample that was deformed with multiple deformation cycles under controlled differential stresses and strain rates at high pressures and high temperatures. Low-angle backscattered electron images thereof showed randomly oriented grains. Most of [...] Read more.
We carried out an electron microscopy study on a polycrystalline olivine sample that was deformed with multiple deformation cycles under controlled differential stresses and strain rates at high pressures and high temperatures. Low-angle backscattered electron images thereof showed randomly oriented grains. Most of the grains were about 10–20 μm wide. The grains were irregular with wavy grain boundaries, indicating high grain boundary mobility during deformation. Transmission electron microscopy (TEM) images showed complex dislocation microstructure characteristics of high temperature, high pressure, and high strain. Free dislocations were predominantly either short and straight screw dislocations or curved dislocations with mixed screw and edge characters. Many of them split into partial dislocations. The differential stress estimated with the free dislocations was ~780 MPa, which was close to the value of differential stress attained in the final deformation cycle. We also observed dense dislocation tangles, which formed dislocation cell substructures under high strain. The existence of dislocation loops and jogs indicated significant climbing activity, providing evidence for high-temperature creep as the dominant deformation mechanism. All of the dislocations observed in this study were exclusively with a [001] Burgers vector. Dislocations with a [100] Burgers vector were absent, suggesting that the activity of the a-slip (i.e., (010)[100] and (001)[100] slip systems) was completely suppressed. These observations support a conclusion that was reported based on an X-ray texture analysis, which considered that a high pressure promotes the activities of the c-slip (i.e., (010)[001] and (100)[001] slip systems). It appears that the transition from the a-slip to the c-slip was complete with multiple deformation cycles at a relatively lower pressure of 5.1 GPa than previously thought, corresponding to a depth of 165 km in the mantle. Full article
(This article belongs to the Special Issue Dislocation in Minerals)
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12 pages, 5323 KiB  
Article
Hematite Exsolutions in Corundum from Cenozoic Basalts in Changle, Shandong Province, China: Crystallographic Orientation Relationships and Interface Characters
by Qianyi Zhao, Shanrong Zhao and Chang Xu
Crystals 2022, 12(7), 905; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12070905 - 24 Jun 2022
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Abstract
Here, we present well-oriented hematite exsolutions in corundum megacrysts from Cenozoic basalt in China. Crystallographic orientation relationships (CORs) and the interface characters between the hematite exsolutions and the corundum host were analyzed by electron backscatter diffraction (EBSD) and high-resolution transmission electron microscope (HRTEM), [...] Read more.
Here, we present well-oriented hematite exsolutions in corundum megacrysts from Cenozoic basalt in China. Crystallographic orientation relationships (CORs) and the interface characters between the hematite exsolutions and the corundum host were analyzed by electron backscatter diffraction (EBSD) and high-resolution transmission electron microscope (HRTEM), respectively. The CORs and the regular interface confirm the exsolution and the exsolution was formed under depressurization based on the crystal chemistry theory. There are three groups of exsolutions intersected with ~60°. Two groups of the exsolutions have the same orientation with the host and the other group is twinned to those two groups. Focused ion beam (FIB) for HRTEM foil preparation was carried out. HRTEM photographs show that there are periodic coherency units at (0001) interface. The measured unit lengths are 6.71–6.72 nm, which are in good agreement with every 17-DCrn011¯2projection or 16-DHem011¯2projection. Based on the results, the possibility is that at the interface, the hematite-corundum phases tend to modulate to achieve the maximum coherency in the geological process during exsolution. This research is helpful to understand the interface characters between the exsolution and host. Full article
(This article belongs to the Special Issue Dislocation in Minerals)
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13 pages, 4604 KiB  
Article
Grossular Exsolution at Pyrope Dislocation: New Evidence for the Ultradeep Origin of Dabie Orogenic Peridotite
by Zhanjun Xie, Xiangwen Liu, Zhenmin Jin and Xiaoqing Liu
Crystals 2022, 12(5), 647; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12050647 - 01 May 2022
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Abstract
Exsolution and dislocation microstructures are an important basis to decipher the conditions of metamorphic deformation and evolution processes of its host minerals and rocks. The grossular-rich exsolution in pyrope-rich garnet grains of Bixiling orogenic crustal cumulative peridotite, Dabie orogen, China, was studied by [...] Read more.
Exsolution and dislocation microstructures are an important basis to decipher the conditions of metamorphic deformation and evolution processes of its host minerals and rocks. The grossular-rich exsolution in pyrope-rich garnet grains of Bixiling orogenic crustal cumulative peridotite, Dabie orogen, China, was studied by electron backscatter diffraction (EBSD), conventional and high-resolution transmission electron microscopy (TEM/HRTEM) and electron-microprobe analysis (EMPA). Our results indicate that the precursor pyrope-rich host grains had undergone plastic deformation and developed numerous dislocation microstructures before the grossular precipitated. When the pressure and/or temperature decreased during the exhumation of subducted slab, the grossular-rich lamellae exsolved and precipitated at the dislocation structures of host and inherited their shapes. EBSD and TEM analyses show that the crystallographic orientation of exsolution is controlled by, and coherent with, the host grain. These exsolution textures and the chemical composition of precursor garnet correspond to a balance pressure–temperature (P–T) condition of >6 GPa and >850 °C based on the previous thermodynamic models, which indicates that the origin depth of the Bixiling garnet peridotite should be more than 200 km. Full article
(This article belongs to the Special Issue Dislocation in Minerals)
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