Paleoproterozoic crust within the Great Falls tectonic zone: Implications for the assembly of southern Laurentia

Abstract

Research Article| February 01, 2002 Paleoproterozoic crust within the Great Falls tectonic zone: Implications for the assembly of southern Laurentia Paul A. Mueller; Paul A. Mueller 1Department of Geological Sciences, University of Florida, Gainesville, Florida 32611, USA Search for other works by this author on: GSW Google Scholar Ann L. Heatherington; Ann L. Heatherington 1Department of Geological Sciences, University of Florida, Gainesville, Florida 32611, USA Search for other works by this author on: GSW Google Scholar Dawn M. Kelly; Dawn M. Kelly 1Department of Geological Sciences, University of Florida, Gainesville, Florida 32611, USA Search for other works by this author on: GSW Google Scholar Joseph L. Wooden; Joseph L. Wooden 2U.S. Geological Survey, Menlo Park, California 94050, USA Search for other works by this author on: GSW Google Scholar David W. Mogk David W. Mogk 3Department of Earth Science, Montana State University, Bozeman, Montana 59717, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Paul A. Mueller 1Department of Geological Sciences, University of Florida, Gainesville, Florida 32611, USA Ann L. Heatherington 1Department of Geological Sciences, University of Florida, Gainesville, Florida 32611, USA Dawn M. Kelly 1Department of Geological Sciences, University of Florida, Gainesville, Florida 32611, USA Joseph L. Wooden 2U.S. Geological Survey, Menlo Park, California 94050, USA David W. Mogk 3Department of Earth Science, Montana State University, Bozeman, Montana 59717, USA Publisher: Geological Society of America Received: 25 May 2001 Revision Received: 26 Sep 2001 Accepted: 17 Oct 2001 First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2002) 30 (2): 127–130. https://doi.org/10.1130/0091-7613(2002)030<0127:PCWTGF>2.0.CO;2 Article history Received: 25 May 2001 Revision Received: 26 Sep 2001 Accepted: 17 Oct 2001 First Online: 02 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 Paul A. Mueller, Ann L. Heatherington, Dawn M. Kelly, Joseph L. Wooden, David W. Mogk; Paleoproterozoic crust within the Great Falls tectonic zone: Implications for the assembly of southern Laurentia. Geology 2002;; 30 (2): 127–130. doi: https://doi.org/10.1130/0091-7613(2002)030<0127:PCWTGF>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 SocietyGeology Search Advanced Search Abstract The Great Falls tectonic zone and the Vulcan structure both have been proposed as the site of a Paleoproterozoic suture between the Archean Hearne and Wyoming provinces. Both hypotheses remain viable because all Precambrian rocks composing the Vulcan structure and much of the Great Falls tectonic zone are buried beneath Phanerozoic cover. The primary exceptions to this are the mafic to felsic igneous and metamorphic rocks of the Little Belt Mountains (Montana), previously considered the northernmost exposures of the Wyoming province. New U-Pb zircon ages from the late kinematic Pinto diorite (207Pb/206Pb age: 1864 ± 5 Ma) and a gneissic unit intruded by the Pinto (207Pb/206Pb age: 1867 ± 6 Ma), however, confirm their Paleoproterozoic age. These rocks exhibit an overall calc-alkaline affinity and the depletion in high field strength elements typical of convergent margin environments. Whole-rock Sm-Nd data (initial epsilon of −1 to +4) and a lack of premagmatic zircons indicate that the magmas were principally derived from a depleted mantle source, not from older crust. These data suggest that at least some rocks within the Great Falls tectonic zone originated at a convergent margin that developed during the closure of an ocean basin along the northwestern margin of the Wyoming craton ca. 1.9 Ga. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.