High-precision U-Pb geochronology in the Minnesota River Valley subprovince and its bearing on the Neoarchean to Paleoproterozoic evolution of the southern Superior Province

Abstract

Research Article| January 01, 2006 High-precision U-Pb geochronology in the Minnesota River Valley subprovince and its bearing on the Neoarchean to Paleoproterozoic evolution of the southern Superior Province M.D. Schmitz; M.D. Schmitz 1Department of Geosciences, Boise State University, Boise, Idaho 83725, USA Search for other works by this author on: GSW Google Scholar S.A. Bowring; S.A. Bowring 2Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA Search for other works by this author on: GSW Google Scholar D.L. Southwick; D.L. Southwick 3Minnesota Geological Survey, University of Minnesota, St. Paul, Minnesota 55114, USA Search for other works by this author on: GSW Google Scholar T.J. Boerboom; T.J. Boerboom 3Minnesota Geological Survey, University of Minnesota, St. Paul, Minnesota 55114, USA Search for other works by this author on: GSW Google Scholar K.R. Wirth K.R. Wirth 4Department of Geology, Macalester College, St. Paul, Minnesota 55105, USA Search for other works by this author on: GSW Google Scholar Author and Article Information M.D. Schmitz 1Department of Geosciences, Boise State University, Boise, Idaho 83725, USA S.A. Bowring 2Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA D.L. Southwick 3Minnesota Geological Survey, University of Minnesota, St. Paul, Minnesota 55114, USA T.J. Boerboom 3Minnesota Geological Survey, University of Minnesota, St. Paul, Minnesota 55114, USA K.R. Wirth 4Department of Geology, Macalester College, St. Paul, Minnesota 55105, USA Publisher: Geological Society of America Received: 19 Sep 2004 Revision Received: 14 Jun 2005 Accepted: 30 Jun 2005 First Online: 08 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2006) 118 (1-2): 82–93. https://doi.org/10.1130/B25725.1 Article history Received: 19 Sep 2004 Revision Received: 14 Jun 2005 Accepted: 30 Jun 2005 First Online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation M.D. Schmitz, S.A. Bowring, D.L. Southwick, T.J. Boerboom, K.R. Wirth; High-precision U-Pb geochronology in the Minnesota River Valley subprovince and its bearing on the Neoarchean to Paleoproterozoic evolution of the southern Superior Province. GSA Bulletin 2006;; 118 (1-2): 82–93. doi: https://doi.org/10.1130/B25725.1 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 SocietyGSA Bulletin Search Advanced Search Abstract High-precision U-Pb ages have been obtained for high-grade gneisses, late-kinematic to postkinematic granitic plutons, and a crosscutting mafic dike of the Archean Minnesota River Valley tectonic subprovince, at the southern ramparts of the Superior craton of North America. The antiquity of the Minnesota River Valley terranes is confirmed by a high-precision U-Pb zircon age of 3422 ± 2 Ma for a tonalitic phase of the Morton Gneiss. Voluminous, late-kinematic monzogranites of the Benson (Ortonville granite) and Morton (Sacred Heart granite) blocks yield identical crystallization ages of 2603 ± 1 Ma, illustrating the synchrony and rapidity of deep crustal melting and plutonism throughout the Minnesota River Valley terranes. Postkinematic, 2591 ± 2 Ma syenogranites and aplitic dikes in both blocks effectively constrain the final penetrative deformation of the Minnesota River Valley subprovince. Monazite growth from 2609 to 2595 Ma in granulitic paragneisses of the Benson and Montevideo blocks is interpreted to record prograde to peak granulite facies metamorphic conditions associated with crustal thickening and magmatism. Neoarchean metamorphism and plutonism are interpreted to record the timing of collisional accretion and terminal suturing of the Mesoarchean continental Minnesota River Valley terranes to the southern margin of the Superior Province, along the western Great Lakes tectonic zone. Subsequent Paleoproterozoic rifting of this margin is recorded by voluminous basaltic dike intrusion, expressed in the Minnesota River Valley by major WNW-trending tholeiitic diabase dikes dated at 2067 ± 1 Ma, only slightly younger than the structurally and geochemically similar 2077 ± 4 Ma Fort Frances (Kenora-Kabetogama) dike swarm of northern Minnesota and adjoining Canada. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.