Late Ottawan extension in the eastern Adirondack Highlands: Evidence from structural studies and zircon and monazite geochronology

Abstract

Research Article| May 01, 2012 Late Ottawan extension in the eastern Adirondack Highlands: Evidence from structural studies and zircon and monazite geochronology Martin S. Wong; Martin S. Wong † 1Department of Geology, Colgate University, Hamilton, New York 13346, USA †E-mail: mswong@colgate.edu Search for other works by this author on: GSW Google Scholar Michael L. Williams; Michael L. Williams 2Department of Geosciences, University of Massachusetts, Amherst, Massachusetts 01003, USA Search for other works by this author on: GSW Google Scholar James M. McLelland; James M. McLelland 1Department of Geology, Colgate University, Hamilton, New York 13346, USA Search for other works by this author on: GSW Google Scholar Michael J. Jercinovik; Michael J. Jercinovik 2Department of Geosciences, University of Massachusetts, Amherst, Massachusetts 01003, USA Search for other works by this author on: GSW Google Scholar Justin Kowalkoski Justin Kowalkoski 1Department of Geology, Colgate University, Hamilton, New York 13346, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Martin S. Wong † 1Department of Geology, Colgate University, Hamilton, New York 13346, USA Michael L. Williams 2Department of Geosciences, University of Massachusetts, Amherst, Massachusetts 01003, USA James M. McLelland 1Department of Geology, Colgate University, Hamilton, New York 13346, USA Michael J. Jercinovik 2Department of Geosciences, University of Massachusetts, Amherst, Massachusetts 01003, USA Justin Kowalkoski 1Department of Geology, Colgate University, Hamilton, New York 13346, USA †E-mail: mswong@colgate.edu Publisher: Geological Society of America Received: 06 Jan 2011 Revision Received: 15 Jul 2011 Accepted: 20 Jul 2011 First Online: 08 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 © 2012 Geological Society of America GSA Bulletin (2012) 124 (5-6): 857–869. https://doi.org/10.1130/B30481.1 Article history Received: 06 Jan 2011 Revision Received: 15 Jul 2011 Accepted: 20 Jul 2011 First Online: 08 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 S. Wong, Michael L. Williams, James M. McLelland, Michael J. Jercinovik, Justin Kowalkoski; Late Ottawan extension in the eastern Adirondack Highlands: Evidence from structural studies and zircon and monazite geochronology. GSA Bulletin 2012;; 124 (5-6): 857–869. doi: https://doi.org/10.1130/B30481.1 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 Syn- to postorogenic collapse is increasingly being recognized as a fundamental process in most orogens, although the mechanism of collapse at mid- to lower-crustal levels is not well understood. The Adirondack Highlands of the Grenville Province in northern New York are an exhumed granulite terrane and represent an ideal setting in which to investigate mid- to lower-crustal orogenic processes. Although the highlands experienced high-grade metamorphism and crustal thickening during the Ottawan orogeny, few extensional shear zones have been recognized in this region. We document a new shear zone in the eastern Adirondack Highlands that accommodated postorogenic extensional collapse during the late Ottawan. The shear zone accommodated extension via noncoaxial top-to-the-southeast shear, although we cannot rule out a significant coaxial vertical thinning component. Some earlier thrust motion may also have occurred in the zone. U-Pb sensitive high-resolution ion microprobe zircon and in situ electron probe U-Th-Pb monazite ages demonstrate that extension occurred from ca. 1050 to 1025 Ma, following peak metamorphism during the Ottawan orogeny. Our results suggest that late Ottawan extension in the Adirondack Highlands was more widespread than previously recognized and was likely driven by gravitational collapse. Extension along this eastern Adirondack Highlands shear zone may connect with the Tawachiche shear zone to the north in Quebec, indicating that tectonic exhumation during the Ottawan occurred on a system of interconnected shear zones. Top-to-the-northeast extension in the eastern Adirondack Highlands was synchronous with top-to-the-northwest extension on the Carthage Colton shear zone in the western Adirondack Highlands, suggesting that the highlands granulite terrane may have been partially exhumed as a large-scale symmetrical gneiss dome. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.