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Title: Deformation of single-crystal clinopyroxenes: 1. Mechanical twinning in diopside and hedenbergite

Abstract

Laboratory deformation experiments were carried out on two single-crystal clinopyroxenes: chrome diopside and hedenbergite. Tests were made in a Griggs solid medium, triaxial, hot creep tester. A confining pressure up 1000 MPa was applied in all experiments. Crystals were deformed at strain rates from 10/sup -4/ to 10/sup -8/ s/sup -1/ and at temperatures from 400/sup 0/C to 1200/sup 0/C. Two orientations of the crystals with respect to the maximum principal compressive stress were tested. The first orientation subjects the (100), (001) and (001), (100) mechanical twinning systems in clinopyroxene to a high resolved shear stress in the sense appropriate for mechanical twinning to occur. The second orientation subjects these systems to an equal resolved shear stress but in the opposite sense so that mechanical twinning is not possible. Effects of temperature and strain rate on the flow stress are observed for the two clinopyroxene compositions. Mechanical twinning on the system (100), (001) is observed to be the primary deformation mechanism in crystals oriented favorably for twinning. The resolved shear stress required for mechanical twinning on this system is 140 MPa for hedenbergite and 100 MPa for chrome diopside. The smaller twinning stresses for diopside are considered to be duemore » to abundant inclusions in the crystals. The mechanical twinning stress is nearly independent of temperature from 400/sup 0/C to 850/sup 0/C and strain rate from 10/sup -4/ to 10/sup -8/ s/sup -1/. Above 850/sup 0/--1000/sup 0/C for diopside and 1000/sup 0/C for hedenbergite, deformation occurs by dislocation glide and is strongly temperature and strain rate dependent.« less

Authors:
;
Publication Date:
Research Org.:
Flow Industries, Inc., Kent, Washington 98031
OSTI Identifier:
6710394
Resource Type:
Journal Article
Journal Name:
J. Geophys. Res.; (United States)
Additional Journal Information:
Journal Volume: 87:B5
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; DIOPSIDE; TWINNING; HEDENBERGITE; DEFORMATION; HIGH TEMPERATURE; STRAIN RATE; VERY HIGH TEMPERATURE; MINERALS; OXYGEN COMPOUNDS; PYROXENES; SILICATE MINERALS; SILICATES; SILICON COMPOUNDS; 580300* - Mineralogy, Petrology, & Rock Mechanics- (-1989)

Citation Formats

Kolle, J J, and Blacic, J D. Deformation of single-crystal clinopyroxenes: 1. Mechanical twinning in diopside and hedenbergite. United States: N. p., 1982. Web. doi:10.1029/JB087iB05p04019.
Kolle, J J, & Blacic, J D. Deformation of single-crystal clinopyroxenes: 1. Mechanical twinning in diopside and hedenbergite. United States. https://doi.org/10.1029/JB087iB05p04019
Kolle, J J, and Blacic, J D. 1982. "Deformation of single-crystal clinopyroxenes: 1. Mechanical twinning in diopside and hedenbergite". United States. https://doi.org/10.1029/JB087iB05p04019.
@article{osti_6710394,
title = {Deformation of single-crystal clinopyroxenes: 1. Mechanical twinning in diopside and hedenbergite},
author = {Kolle, J J and Blacic, J D},
abstractNote = {Laboratory deformation experiments were carried out on two single-crystal clinopyroxenes: chrome diopside and hedenbergite. Tests were made in a Griggs solid medium, triaxial, hot creep tester. A confining pressure up 1000 MPa was applied in all experiments. Crystals were deformed at strain rates from 10/sup -4/ to 10/sup -8/ s/sup -1/ and at temperatures from 400/sup 0/C to 1200/sup 0/C. Two orientations of the crystals with respect to the maximum principal compressive stress were tested. The first orientation subjects the (100), (001) and (001), (100) mechanical twinning systems in clinopyroxene to a high resolved shear stress in the sense appropriate for mechanical twinning to occur. The second orientation subjects these systems to an equal resolved shear stress but in the opposite sense so that mechanical twinning is not possible. Effects of temperature and strain rate on the flow stress are observed for the two clinopyroxene compositions. Mechanical twinning on the system (100), (001) is observed to be the primary deformation mechanism in crystals oriented favorably for twinning. The resolved shear stress required for mechanical twinning on this system is 140 MPa for hedenbergite and 100 MPa for chrome diopside. The smaller twinning stresses for diopside are considered to be due to abundant inclusions in the crystals. The mechanical twinning stress is nearly independent of temperature from 400/sup 0/C to 850/sup 0/C and strain rate from 10/sup -4/ to 10/sup -8/ s/sup -1/. Above 850/sup 0/--1000/sup 0/C for diopside and 1000/sup 0/C for hedenbergite, deformation occurs by dislocation glide and is strongly temperature and strain rate dependent.},
doi = {10.1029/JB087iB05p04019},
url = {https://www.osti.gov/biblio/6710394}, journal = {J. Geophys. Res.; (United States)},
number = ,
volume = 87:B5,
place = {United States},
year = {Mon May 10 00:00:00 EDT 1982},
month = {Mon May 10 00:00:00 EDT 1982}
}