Ridge-trench interactions and the Neogene tectonic evolution of the Magdalena shelf and southern Gulf of California: Insights from detrital zircon U-Pb ages from the Magdalena fan and adjacent areas

Research Article| November 01, 2007 Ridge-trench interactions and the Neogene tectonic evolution of the Magdalena shelf and southern Gulf of California: Insights from detrital zircon U-Pb ages from the Magdalena fan and adjacent areas John M. Fletcher; John M. Fletcher 1Departamento de Geologia, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Ensenada, Baja California, Mexico Search for other works by this author on: GSW Google Scholar Marty Grove; Marty Grove 2Department of Earth and Space Sciences, 3806 Geology Building, University of California, Los Angeles, California 90095-1567, USA Search for other works by this author on: GSW Google Scholar David Kimbrough; David Kimbrough 3Department of Geological Sciences, 5500 Campanile Drive, San Diego State University, San Diego, California 92182-1020, USA Search for other works by this author on: GSW Google Scholar Oscar Lovera; Oscar Lovera 4Department of Earth and Space Sciences, 3806 Geology Building, University of California, Los Angeles, California 90095-1567, USA Search for other works by this author on: GSW Google Scholar George E. Gehrels George E. Gehrels 5Department of Geosciences, Gould-Simpson Building #77, 1040 E 4th Street, University of Arizona, Tucson, Arizona 85721, USA Search for other works by this author on: GSW Google Scholar Author and Article Information John M. Fletcher 1Departamento de Geologia, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Ensenada, Baja California, Mexico Marty Grove 2Department of Earth and Space Sciences, 3806 Geology Building, University of California, Los Angeles, California 90095-1567, USA David Kimbrough 3Department of Geological Sciences, 5500 Campanile Drive, San Diego State University, San Diego, California 92182-1020, USA Oscar Lovera 4Department of Earth and Space Sciences, 3806 Geology Building, University of California, Los Angeles, California 90095-1567, USA George E. Gehrels 5Department of Geosciences, Gould-Simpson Building #77, 1040 E 4th Street, University of Arizona, Tucson, Arizona 85721, USA Publisher: Geological Society of America Received: 18 May 2005 Revision Received: 03 Jan 2007 Accepted: 02 Feb 2007 First Online: 08 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 The Geological Society of America, Inc. GSA Bulletin (2007) 119 (11-12): 1313–1336. https://doi.org/10.1130/B26067.1 Article history Received: 18 May 2005 Revision Received: 03 Jan 2007 Accepted: 02 Feb 2007 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 John M. Fletcher, Marty Grove, David Kimbrough, Oscar Lovera, George E. Gehrels; Ridge-trench interactions and the Neogene tectonic evolution of the Magdalena shelf and southern Gulf of California: Insights from detrital zircon U-Pb ages from the Magdalena fan and adjacent areas. GSA Bulletin 2007;; 119 (11-12): 1313–1336. doi: https://doi.org/10.1130/B26067.1 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 Magdalena fan is an apparently beheaded submarine depocenter that has figured prominently in reconstructions of middle to late Miocene Pacific–North American plate interactions. The deposit accumulated rapidly at the base of the continental slope on top of newly formed oceanic crust of the Magdalena microplate from 14.5 to 13 Ma. Subduction of this crust ceased as the Pacific-Magdalena spreading center encountered the trench. The widely accepted two-phase kinematic model for the formation of the Gulf of California holds that ∼300 km of dextral shear between the Pacific and North American plates occurred along faults west of Baja California prior to the onset of dextral-transtensional shearing in the gulf ca. 6 Ma. We measured 1796 detrital zircon U-Pb ages from 65 samples in an effort to characterize the provenance of the fan, determine its source region, and define the cumulative dextral slip along faults offshore of southwestern Baja California. Zircons from the fan are dominantly 120–65 Ma with subordinate 15–35 Ma grains. Excellent matches to the fan can be obtained by mixing Magdalena shelf strata and/or adding detritus from the west-draining portion of the Los Cabos block. The same cannot be accomplished with zircons from the east-draining portion of the Los Cabos block and mainland Mexico. Our results favor a western Baja source region for the fan and suggest that cumulative dextral slip along faults west of Baja was <150 km, much less than previously believed. We propose that the fan was fed by erosional denudation of the Magdalena shelf produced by increased mantle buoyancy due to the ridge-trench juxtaposition. The fan's source was cut off when faults west of Baja California began to accommodate transtensional shearing and form rift basins that captured detritus that previously reached the trench. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.