Tectonic origin for Sudbury, Ontario, shatter cones

Abstract

Research Article| December 01, 1979 Tectonic origin for Sudbury, Ontario, shatter cones MICHAEL E. FLEET MICHAEL E. FLEET 1Department of Geology, University of Western Ontario, London, Ontario N6A 5B7, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information MICHAEL E. FLEET 1Department of Geology, University of Western Ontario, London, Ontario N6A 5B7, Canada Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1979) 90 (12): 1177–1182. https://doi.org/10.1130/0016-7606(1979)90<1177:TOFSOS>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation MICHAEL E. FLEET; Tectonic origin for Sudbury, Ontario, shatter cones. GSA Bulletin 1979;; 90 (12): 1177–1182. doi: https://doi.org/10.1130/0016-7606(1979)90<1177:TOFSOS>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 Detailed petrographic examination of Mississagi quartzite from the Sudbury basin in southeastern Ontario, Canada, reveals that the conical fractures previously identified as shatter cones are lined with sheet-silicate minerals characterized by oriented biotite and chlorite. These mineralized conical fractures crosscut the main deformation features in the rocks. Deformation features in hand specimens from the sampled localities — south Kelly Lake and Laurentian University campus — include serrated and interlocked quartz grain boundaries, extensive subgrain boundary development within quartz grains, primary recrystallization of quartz, and plagioclase cataclasis; these features were probably formed during the Penokean orogeny. The conical fracture zones are therefore late Penokean in age. The mineralization associated with the conical fractures developed by syntectonic crystallization under conditions of nonhydrostatic compressive stress and low strain rates. This is indicated by, in particular, en echelon sigmoidal biotite and chlorite aggregates, crosscutting grain relationships, and slickenside surfaces with steps and fibrous striations. The orientation of the sigmoidal biotite and chlorite aggregates is consistent with σ1, parallel to the cone axes. Thus, the conical fractures postdate emplacement of the nickel intrusion, and they do not appear to be a crypto-explosion feature. 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.