Preferred orientation in experimentally deformed stishovite: implications for deformation mechanisms
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Although the crystal structure of the high-pressure SiO2 polymorph stishovite has been studied in detail, little is known about the development of crystallographic preferred orientation (CPO) during deformation in stishovite. Insight into CPO and associated deformation mechanics of stishovite would provide important information for understanding subduction of quartz-bearing crustal rocks into the mantle. To study CPO development, we converted a natural sample of flint to stishovite in a laser-heated diamond anvil cell and compressed the stishovite aggregate up to 38 GPa. We collected diffraction patterns in radial geometry to examine in situ development of crystallographic preferred orientation and find that (001) poles preferentially align with the compression direction. Viscoplastic self-consistent modeling suggests the most likely slip systems at high pressure and ambient temperature are pyramidal and basal slip.
KeywordsStishovite Preferred orientation Diamond anvil cell Slip systems High pressure/stress
This project was supported by grants from CDAC and NSF EAR 1343908. Portions of this work were performed at GeoSoilEnviroCARS (Sector 13) and at HPCAT (Sector 16), Advanced Photon Source (APS), Argonne National Laboratory. GeoSoilEnviroCARS is supported by the National Science Foundation–Earth Sciences (EAR-1128799) and Department of Energy–Geosciences (DE-FG02-94ER14466). HPCAT operations are supported by DOE-NNSA under Award No. DE-NA0001974 and DOE-BES under Award No. DE-FG02-99ER45775, with partial instrumentation funding by NSF. APS is supported by DOE-BES, under Contract No. DE-AC02-06CH11357. P. Kaercher is grateful to Jung-Fu Lin for the use of his diamond anvil cells and to Alastair MacDowell for discussion and advice. Suggestions from reviewers improved the manuscript and are much appreciated.
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