Plastic deformation in two single crystal clinopyroxenes

Technical Report · Sun Jun 01 00:00:00 EDT 1980

DOI:https://doi.org/10.2172/5209300· OSTI ID:5209300

Kolle, J J

Laboratory deformation experiments were carried out on two single crystal clinopyroxenes, chrome diopside, and hedenbergite. The tests were made in a Grigg's solid medium, triaxial, hot creep tester. A confining pressure of 10 kilobars was applied in all the experiments. The crystals were deformed at strain rates from 10/sup -4/ s/sup -1/ to 10/sup -8/ s/sup -1/ and at temperatures from 400/sup 0/C to 1200/sup 0/C. At temperatures above 900/sup 0/C and applied stresses less than 5.2 kilobars flow in hedenbergite occurs by climb controlled dislocation glide. The results for mechanical twinning predict that this is not an important deformation mechanism unless the resolved shear stress on the twinning system exceeds 1.4 kilobars. The lack of dependence of twinning stress on strain rate implies that large rapid strains will occur in this mineral if the twinning stress is reached. This may provide a mechanism for deep focus earthquakes. The independence of twinning stress in clinopyroxenes from temperature, strain rate, or composition allows the use of this mineral as a geopiezometer. At plate margins where stresses are high the presence of mechanically twinned clinopyroxene grains allows the determination of the orientation and magnitude of the stresses responsible for the deformation.

• Research Organization: Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 5209300
• Report Number(s): LA-8387-T
• Resource Relation: Other Information: Thesis
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
DIOPSIDE
DEFORMATION
TWINNING
HEDENBERGITE
BENCH-SCALE EXPERIMENTS
CREEP
CRYSTAL STRUCTURE
EXPERIMENTAL DATA
PLASTICITY
STRAIN RATE
TEMPERATURE DEPENDENCE
DATA
INFORMATION
MECHANICAL PROPERTIES
MINERALS
NUMERICAL DATA
OXYGEN COMPOUNDS
PYROXENES
SILICATES
SILICON COMPOUNDS
580300* - Mineralogy
Petrology
& Rock Mechanics- (-1989)