کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6444614 | 1640488 | 2016 | 16 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Microstructural evidence for the transition from dislocation creep to dislocation-accommodated grain boundary sliding in naturally deformed plagioclase
ترجمه فارسی عنوان
شواهد ریز ساختاری برای گذار از خزش جابجایی به مرز دانه جابجایی در پلاژیوکلاز به طور طبیعی شکل پذیر
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
زمین شناسی
چکیده انگلیسی
We use quantitative microstructural analysis including misorientation analysis based on electron backscatter diffraction (EBSD) data to investigate deformation mechanisms of naturally deformed plagioclase in an amphibolite gabbro mylonite. The sample is from lower oceanic crust exposed near the Southwest Indian Ridge, and it has a high ratio of recrystallized matrix grains to porphyroclasts. Microstructures preserved in porphyroclasts suggest that early deformation was achieved principally by dislocation creep with subgrain rotation recrystallization; recrystallized grain (average diameter â¼8 μm) microstructures indicate that subsequent grain boundary sliding (GBS) was active in the continued deformation of the recrystallized matrix. The recrystallized matrix shows four-grain junctions, randomized misorientation axes, and a shift towards higher angles for neighbor-pair misorientations, all indicative of GBS. The matrix grains also exhibit a shape preferred orientation, a weak lattice preferred orientation consistent with slip on multiple slip systems, and intragrain microstructures indicative of dislocation movement. The combination of these microstructures suggest deformation by dislocation-accommodated GBS (DisGBS). Strain localization within the recrystallized matrix was promoted by a transition from grain size insensitive dislocation creep to grain size sensitive GBS, and sustained by the maintenance of a small grain size during superplasticity.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Structural Geology - Volume 92, November 2016, Pages 30-45
Journal: Journal of Structural Geology - Volume 92, November 2016, Pages 30-45
نویسندگان
Elena A. Miranda, Greg Hirth, Barbara E. John,