Geology and geochronology of Paleozoic rocks in western Acatlán Complex, southern Mexico: Evidence for contiguity across an extruded high-pressure belt and constraints on Paleozoic reconstructions

Abstract

Research Article| November 01, 2009 Geology and geochronology of Paleozoic rocks in western Acatlán Complex, southern Mexico: Evidence for contiguity across an extruded high-pressure belt and constraints on Paleozoic reconstructions Carlos Ortega-Obregon; Carlos Ortega-Obregon 1Departamento de Geología Regional, Instituto de Geología, Universidad Nacional Autonoma de México, Mexico D.F. 04510, Mexico Search for other works by this author on: GSW Google Scholar J. Duncan Keppie; J. Duncan Keppie † 1Departamento de Geología Regional, Instituto de Geología, Universidad Nacional Autonoma de México, Mexico D.F. 04510, Mexico †E-mail: duncan@servidor.unam.mx Search for other works by this author on: GSW Google Scholar J. Brendan Murphy; J. Brendan Murphy 2Department of Earth Sciences, Saint Francis Xavier University, Antigonish, Nova Scotia B2G 2W5, Canada Search for other works by this author on: GSW Google Scholar J.K.W. Lee; J.K.W. Lee 3Department of Geology and Environmental Sciences, Queens University, Kingston, Ontario K7L3NG, Canada Search for other works by this author on: GSW Google Scholar Amabel Ortega-Rivera Amabel Ortega-Rivera 4Instituto de Geología, Estación Regional del Noroeste, Apartado Postal 1039, Universidad Nacional Autonoma de México, Hermosillo, Sonora 83000, Mexico Search for other works by this author on: GSW Google Scholar Author and Article Information Carlos Ortega-Obregon 1Departamento de Geología Regional, Instituto de Geología, Universidad Nacional Autonoma de México, Mexico D.F. 04510, Mexico J. Duncan Keppie † 1Departamento de Geología Regional, Instituto de Geología, Universidad Nacional Autonoma de México, Mexico D.F. 04510, Mexico J. Brendan Murphy 2Department of Earth Sciences, Saint Francis Xavier University, Antigonish, Nova Scotia B2G 2W5, Canada J.K.W. Lee 3Department of Geology and Environmental Sciences, Queens University, Kingston, Ontario K7L3NG, Canada Amabel Ortega-Rivera 4Instituto de Geología, Estación Regional del Noroeste, Apartado Postal 1039, Universidad Nacional Autonoma de México, Hermosillo, Sonora 83000, Mexico †E-mail: duncan@servidor.unam.mx Publisher: Geological Society of America Received: 15 Dec 2008 Revision Received: 19 Feb 2009 Accepted: 03 Mar 2009 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 © 2009 Geological Society of America GSA Bulletin (2009) 121 (11-12): 1678–1694. https://doi.org/10.1130/B26597.1 Article history Received: 15 Dec 2008 Revision Received: 19 Feb 2009 Accepted: 03 Mar 2009 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 Carlos Ortega-Obregon, J. Duncan Keppie, J. Brendan Murphy, J.K.W. Lee, Amabel Ortega-Rivera; Geology and geochronology of Paleozoic rocks in western Acatlán Complex, southern Mexico: Evidence for contiguity across an extruded high-pressure belt and constraints on Paleozoic reconstructions. GSA Bulletin 2009;; 121 (11-12): 1678–1694. doi: https://doi.org/10.1130/B26597.1 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 The Acatlán Complex straddles a high-pressure belt previously interpreted as either: (1) a suture zone within the Iapetus or the Rheic oceans, which would have a contrasting geological record across the suture; or (2) a tectonic slice extruded into the upper plate, which would imply contiguity across the complex. Distinguishing between these hypotheses is critical to paleogeographic reconstructions. Examination of the western Acatlán Complex reveals the following: (1) deposition of clastic rocks between 654 and 464 Ma; (2) intrusion of bimodal Ordovician bodies at ca. 464 Ma; (3) high-grade deformation with cooling through 400 °C by ~360–335 Ma; (4) deposition of clastic rocks and pillow lavas after ~350–400 Ma; (5) deformation accompanied by greenschist facies metamorphism at ca. 335 Ma; (6) deposition of clastic and bimodal volcanic rocks at ca. 327 Ma; (7) ~320–270 Ma subgreenschist deformation; (8) deposition of the Middle-Upper Permian sedimentary rocks; and (9) intrusion of a 61 ± 1 Ma diorite followed by early Cenozoic (Laramide) ENE folding and faulting. Zircon ages (~350–400, 570–505, 827–890 Ma, 0.9–1.3 Ga) suggest both local and Amazonian sources with deposition above a local Mesoproterozoic (Oaxacan) basement on the southern margin of the Rheic Ocean. This geological record is very similar to that of the eastern Acatlán Complex, which supports the extrusion hypothesis, a model that may be applicable to other orogens. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.