Comparison of microstructures in superplastically deformed synthetic materials and natural mylonites: Mineral aggregation via grain boundary sliding

Abstract

Research Article| September 01, 2013 Comparison of microstructures in superplastically deformed synthetic materials and natural mylonites: Mineral aggregation via grain boundary sliding Takehiko Hiraga; Takehiko Hiraga 1Earthquake Research Institute, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan Search for other works by this author on: GSW Google Scholar Tomonori Miyazaki; Tomonori Miyazaki 1Earthquake Research Institute, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan Search for other works by this author on: GSW Google Scholar Hidehiro Yoshida; Hidehiro Yoshida 2Advanced Ceramics Group, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan Search for other works by this author on: GSW Google Scholar Mark E. Zimmerman Mark E. Zimmerman 3Department of Geology and Geophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Takehiko Hiraga 1Earthquake Research Institute, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan Tomonori Miyazaki 1Earthquake Research Institute, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan Hidehiro Yoshida 2Advanced Ceramics Group, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan Mark E. Zimmerman 3Department of Geology and Geophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA Publisher: Geological Society of America Received: 22 Jan 2013 Revision Received: 15 Apr 2013 Accepted: 18 Apr 2013 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2013 Geological Society of America Geology (2013) 41 (9): 959–962. https://doi.org/10.1130/G34407.1 Article history Received: 22 Jan 2013 Revision Received: 15 Apr 2013 Accepted: 18 Apr 2013 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Takehiko Hiraga, Tomonori Miyazaki, Hidehiro Yoshida, Mark E. Zimmerman; Comparison of microstructures in superplastically deformed synthetic materials and natural mylonites: Mineral aggregation via grain boundary sliding. Geology 2013;; 41 (9): 959–962. doi: https://doi.org/10.1130/G34407.1 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 SocietyGeology Search Advanced Search Abstract We conducted compressional, tensile, and torsional creep experiments on fine-grained forsterite plus Ca-bearing pyroxene aggregates. A distinct microstructure with aggregation of the same phase in the direction of compression was formed in our samples after all the experiments. The stress–strain rate relationship, grain-size dependent flow strength, and the achievement of large tensile strain all indicate that samples underwent creep due to grain boundary sliding (GBS). As a result of GBS, grain-switching events allow dispersed phases to contact grains of the same phase and orient in the direction of compression. We identify similar aggregated microstructures in previously reported micrographs of polymineralic granite-origin ultramylonites. Mineral phase mixing through GBS, which helps to retain fine grain size in rocks due to grain boundary pinning, has been speculated to occur during formation of mylonites. However, our results contradict this hypothesis because mineral aggregation through GBS promotes demixing rather than mixing of the mineral phases. GBS processes alone will not promote a transformation of well-developed monomineralic bands to polymineralic bands during mylonitization. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.