DEFORMATION AND POLYMORPHISM OF ENSTATITE UNDER SHEAR STRESS

Abstract

Research Article| August 01, 1967 DEFORMATION AND POLYMORPHISM OF ENSTATITE UNDER SHEAR STRESS R. E RIECKER; R. E RIECKER AIR FORCE CAMBRIDGE RESEARCH LABORATORIES, LAURENCE G. HANSCOM FIELD, BEDFORD, MASSACHUSETTS 01730 Search for other works by this author on: GSW Google Scholar T. P ROONEY T. P ROONEY AIR FORCE CAMBRIDGE RESEARCH LABORATORIES, LAURENCE G. HANSCOM FIELD, BEDFORD, MASSACHUSETTS 01730 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1967) 78 (8): 1045–1054. https://doi.org/10.1130/0016-7606(1967)78[1045:DAPOEU]2.0.CO;2 Article history received: 20 Jul 1966 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation R. E RIECKER, T. P ROONEY; DEFORMATION AND POLYMORPHISM OF ENSTATITE UNDER SHEAR STRESS. GSA Bulletin 1967;; 78 (8): 1045–1054. doi: https://doi.org/10.1130/0016-7606(1967)78[1045:DAPOEU]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract An opposed anvil shear press was used to determine the mechanical properties and the polymorphism of MgSiO3 at normal pressures to 50 kb, at temperatures to 920°C, and at strain rates ranging from 10/sec to l0−4/sec. Experiments were made on natural single crystals of enstatite from Bamle, Norway, synthetic MgSiO3, and stoichiometric mixtures of MgO and SiO2. The natural enstatites have a shear strength of 14.9 kb at 50-kb normal pressure and 27°C. They decrease in strength to 5.5 kb at 40-kb normal pressure and 920°C. All specimens yielded clinoenstatite from orthorhombic-starting materials when they were sheared for longer than 1 sec. This suggests that shear stress greatly enlarges the stability field of clinoenstatite. Compression tests held for 24 hours at 80-kb normal pressure and 27°C yielded only orthoenstatite.Specimens deformed at high pressures and temperatures exhibit kink bands with the slip system identified as T = (100), t = [001]. Although the volume change from orthorhombic to monoclinic MgSiO3 is small, it appears that the inversion is sufficiently large to produce seismic energy. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.