Divergent double subduction: Tectonic and petrologic consequences

Abstract

Research Article| August 01, 1997 Divergent double subduction: Tectonic and petrologic consequences Alvar Soesoo; Alvar Soesoo 1Department of Earth Sciences, Monash University, Melbourne, Victoria 3168, Australia Search for other works by this author on: GSW Google Scholar Paul D. Bons; Paul D. Bons 1Department of Earth Sciences, Monash University, Melbourne, Victoria 3168, Australia Search for other works by this author on: GSW Google Scholar David R. Gray; David R. Gray 1Department of Earth Sciences, Monash University, Melbourne, Victoria 3168, Australia Search for other works by this author on: GSW Google Scholar David A. Foster David A. Foster 2School of Earth Sciences, LaTrobe University, Melbourne, Victoria 3083, Australia Search for other works by this author on: GSW Google Scholar Author and Article Information Alvar Soesoo 1Department of Earth Sciences, Monash University, Melbourne, Victoria 3168, Australia Paul D. Bons 1Department of Earth Sciences, Monash University, Melbourne, Victoria 3168, Australia David R. Gray 1Department of Earth Sciences, Monash University, Melbourne, Victoria 3168, Australia David A. Foster 2School of Earth Sciences, LaTrobe University, Melbourne, Victoria 3083, Australia Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1997) 25 (8): 755–758. https://doi.org/10.1130/0091-7613(1997)025<0755:DDSTAP>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 Alvar Soesoo, Paul D. Bons, David R. Gray, David A. Foster; Divergent double subduction: Tectonic and petrologic consequences. Geology 1997;; 25 (8): 755–758. doi: https://doi.org/10.1130/0091-7613(1997)025<0755:DDSTAP>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 Divergent double subduction, involving removal of an oceanic basin from both sides and collision, has distinct fingerprints of magmatism and significant implications for the tectono-magmatic evolution of orogenic belts. The complete evolution of a divergent double subduction system involves four stages: (1) initial interaction between the two divergent subduction zones on both sides of a single oceanic plate; (2) closure of the oceanic basin when the two overriding plates meet, followed by (3) detachment of the oceanic lithosphere from the overlying crust and sedimentary sections; (4) sinking and disappearance of the oceanic slab into the mantle. Detachment of the oceanic slab leads to intense decompressional melting of mantle and triggers melting of accretionary-wedge strata and lower crust, resulting in large-scale magmatic and volcanic activity. The main consequences of a divergent double subduction system are that it produces opposed thrust systems, extensive long-lived granitoid magmatism with mantle isotopic signature, and volcanism that evolves toward bimodalism. This model can be applied to the western half of the Paleozoic Lachlan fold belt (southeastern Australia) to explain the wide-scale Silurian to early Carboniferous granitoid magmatism, its spatial and temporal relationships, and late bimodal magmatism. Closure of the oceanic basin is thought to have occurred during the Early to Middle Devonian. Detachment of the oceanic slab led to felsic to intermediate-composition magmatism. Bimodal volcanism involving local basaltic flows is a reflection of subsequent sinking of the slab. 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.