LAYERED MYLONITE FROM BEARTOOTH MOUNTAINS, MONTANA

Abstract

Research Article| August 01, 1964 LAYERED MYLONITE FROM BEARTOOTH MOUNTAINS, MONTANA MARTIN PRINZ; MARTIN PRINZ DEPT. GEOLOGY, TUFTS UNIVERSITY, MEDFORD, MASS.; DEPT. GEOLOGY, COLUMBIA UNIVERSITY, NEW YORK, N.Y. Search for other works by this author on: GSW Google Scholar ARIE POLDERVAART ARIE POLDERVAART DEPT. GEOLOGY, TUFTS UNIVERSITY, MEDFORD, MASS.; DEPT. GEOLOGY, COLUMBIA UNIVERSITY, NEW YORK, N.Y. Search for other works by this author on: GSW Google Scholar Author and Article Information MARTIN PRINZ DEPT. GEOLOGY, TUFTS UNIVERSITY, MEDFORD, MASS.; DEPT. GEOLOGY, COLUMBIA UNIVERSITY, NEW YORK, N.Y. ARIE POLDERVAART DEPT. GEOLOGY, TUFTS UNIVERSITY, MEDFORD, MASS.; DEPT. GEOLOGY, COLUMBIA UNIVERSITY, NEW YORK, N.Y. Publisher: Geological Society of America Received: 20 Feb 1964 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1964, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1964) 75 (8): 741–744. https://doi.org/10.1130/0016-7606(1964)75[741:LMFBMM]2.0.CO;2 Article history Received: 20 Feb 1964 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation MARTIN PRINZ, ARIE POLDERVAART; LAYERED MYLONITE FROM BEARTOOTH MOUNTAINS, MONTANA. GSA Bulletin 1964;; 75 (8): 741–744. doi: https://doi.org/10.1130/0016-7606(1964)75[741:LMFBMM]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 Localized, intense shearing of a metadolerite dike has produced a distinctly layered mylonite from originally homogeneous rock. Observations indicate that during mylonitization pyroxenes were more ductile than plagioclase, and that layering resulted from the different behavior of these minerals under shearing stress. The normal metadolerite has 58 per cent salic, and 42 per cent femic minerals. An analyzed dark layer of the mylonite has 60 per cent femic minerals, whereas an analyzed light layer shows 86 per cent salic minerals. Pneumatolytic alteration accompanied mylonitization but did not produce the layering. The layered mylonite illustrates that metamorphic differentiation may result from mechanical deformation only, but this probably occurs rarely. However, shearing and partial mylonitization may be more widespread and may produce privileged directions, planes, and layers for mimetic recrystallization and growth during subsequent metamorphism. Thus lineated, striped, and layered ortho-amphibolites may be formed from originally homogeneous rocks of basaltic composition. 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.