Arc abandonment as a cause for passive continental rifting: Comparison of the Jurassic Mexican Borderland rift and the Cenozoic Rio Grande rift

Abstract

Research Article| September 01, 1999 Arc abandonment as a cause for passive continental rifting: Comparison of the Jurassic Mexican Borderland rift and the Cenozoic Rio Grande rift Timothy F. Lawton; Timothy F. Lawton 1Department of Geological Sciences, New Mexico State University, Las Cruces, New Mexico 88003, USA Search for other works by this author on: GSW Google Scholar Nancy J. McMillan Nancy J. McMillan 1Department of Geological Sciences, New Mexico State University, Las Cruces, New Mexico 88003, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Timothy F. Lawton 1Department of Geological Sciences, New Mexico State University, Las Cruces, New Mexico 88003, USA Nancy J. McMillan 1Department of Geological Sciences, New Mexico State University, Las Cruces, New Mexico 88003, USA Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1999) 27 (9): 779–782. https://doi.org/10.1130/0091-7613(1999)027<0779:AAAACF>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Timothy F. Lawton, Nancy J. McMillan; Arc abandonment as a cause for passive continental rifting: Comparison of the Jurassic Mexican Borderland rift and the Cenozoic Rio Grande rift. Geology 1999;; 27 (9): 779–782. doi: https://doi.org/10.1130/0091-7613(1999)027<0779:AAAACF>2.3.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 Two rift systems, one of late Mesozoic age and the other of Tertiary age, in the southern Cordillera of North America formed along the inner flanks of former continental arcs. Both rift systems were initiated when arc magmatism abandoned its former inboard extent as a result of retrograde motion of the subducted slab. Similarities in stratigraphy and geochemistry preceding and during crustal extension of each rift system suggest a three-phase magmatic-depositional model for the formation of passive continental rifts above a foundering subducted slab. Continental arc magmatism associated with normal subduction weakens the continental crust during phase 1. Phase 2 involves incipient retrograde motion of the slab, or slab foundering, initiating mantle return into the wedge-shaped volume between slab and overlying continental lithosphere. This causes crustal extension, lithospheric melting, and deposition of conglomerate in nascent rift basins stratigraphically above and adjacent to the extinguished arc. Caldera-related silicic volcanism defines an ignimbrite flare-up, accompanied by extrusion of lithosphere-derived basalt. Mafic volcanism, block faulting, and extensional sedimentary-basin formation continue after the end of silicic volcanism. During phase 3, decompression partial melting of convecting asthenosphere creates basalts with ocean-island chemical affinities intercalated with alluvial or marine sedimentary rocks in extensional basins. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.