Metamorphism in the Agnew Lake Area, Sudbury District, Ontario, Canada

Abstract

Research Article| October 01, 1964 Metamorphism in the Agnew Lake Area, Sudbury District, Ontario, Canada K. D CARD K. D CARD Box 1030, Dept. Mines, Sudbury, Ontario, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information K. D CARD Box 1030, Dept. Mines, Sudbury, Ontario, Canada Publisher: Geological Society of America Received: 20 Mar 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 (10): 1011–1030. https://doi.org/10.1130/0016-7606(1964)75[1011:MITALA]2.0.CO;2 Article history Received: 20 Mar 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 K. D CARD; Metamorphism in the Agnew Lake Area, Sudbury District, Ontario, Canada. GSA Bulletin 1964;; 75 (10): 1011–1030. doi: https://doi.org/10.1130/0016-7606(1964)75[1011:MITALA]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 Metamorphism occurred in the Agnew Lake area about 1600 m. y. ago during the Penokean orogeny. Mafic igneous, pelitic meta-sedimentary, and quartzofeldspathic rocks were metamorphosed under conditions ranging from the low greenschist (chlorite-grade) to low almandine amphibolite (staurolite-grade) facies. The metamorphic zones have a nodal distribution. The sequence of mineralogic and assemblage changes with advancing metamorphic grade can be portrayed diagrammatically and by equations. There is regular partitioning of some elements, notably Mn, among coexisting biotite, staurolite, and garnet. Study of the interrelationships of metamorphic porphyroblasts and fabric elements provides evidence for a threefold division of events; an early “plastic” phase of deformation accompanied by growth of “low-grade” minerals such as muscovite and chlorite; the major period of metamorphism and the growth of “high-grade” minerals such as staurolite in a static environment; a late “brittle” deformation phase with minor “retrograde” metamorphism. The composition of pyrrhotites which have supposedly equilibrated with pyrite during metamorphism indicate metamorphic temperatures of 400°–570° C in the upper greenschist and almandine amphibolite facies. Calculations based on the pyrrhotite data indicate thermal gradients of 75°–150° C per km. 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.