Bivergent thrust wedges surrounding oceanic island arcs: Insight from observations and sandbox models of the northeastern Caribbean plate

Research Article| November 01, 2009 Bivergent thrust wedges surrounding oceanic island arcs: Insight from observations and sandbox models of the northeastern Caribbean plate Uri S. ten Brink; Uri S. ten Brink † 1U.S. Geological Survey, Woods Hole, Massachusetts 02543, USA †E-mail: utenbrink@usgs.gov Search for other works by this author on: GSW Google Scholar Stephen Marshak; Stephen Marshak 2Department of Geological Sciences, University of Illinois, Urbana, Illinois 61801, USA Search for other works by this author on: GSW Google Scholar José-Luis Granja Bruña José-Luis Granja Bruña 3Geodynamics Department, Universidad Complutense de Madrid, Madrid 28040, Spain Search for other works by this author on: GSW Google Scholar Author and Article Information Uri S. ten Brink † 1U.S. Geological Survey, Woods Hole, Massachusetts 02543, USA Stephen Marshak 2Department of Geological Sciences, University of Illinois, Urbana, Illinois 61801, USA José-Luis Granja Bruña 3Geodynamics Department, Universidad Complutense de Madrid, Madrid 28040, Spain †E-mail: utenbrink@usgs.gov Publisher: Geological Society of America Received: 11 Jul 2008 Revision Received: 30 Dec 2008 Accepted: 24 Jan 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): 1522–1536. https://doi.org/10.1130/B26512.1 Article history Received: 11 Jul 2008 Revision Received: 30 Dec 2008 Accepted: 24 Jan 2009 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Uri S. ten Brink, Stephen Marshak, José-Luis Granja Bruña; Bivergent thrust wedges surrounding oceanic island arcs: Insight from observations and sandbox models of the northeastern Caribbean plate. GSA Bulletin 2009;; 121 (11-12): 1522–1536. doi: https://doi.org/10.1130/B26512.1 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 At several localities around the world, thrust belts have developed on both sides of oceanic island arcs (e.g., Java-Timor, Panama, Vanuatu, and the northeastern Caribbean). In these localities, the overall vergence of the backarc thrust belt is opposite to that of the forearc thrust belt. For example, in the northeastern Caribbean, a north-verging accretionary prism lies to the north of the Eastern Greater Antilles arc (Hispaniola and Puerto Rico), whereas a south-verging thrust belt called the Muertos thrust belt lies to the south. Researchers have attributed such bivergent geometry to several processes, including: reversal of subduction polarity; subduction-driven mantle flow; stress transmission across the arc; gravitational spreading of the arc; and magmatic inflation within the arc. New observations of deformational features in the Muertos thrust belt and of fault geometries produced in sandbox kinematic models, along with examination of published studies of island arcs, lead to the conclusion that the bivergence of thrusting in island arcs can develop without reversal of subduction polarity, without subarc mantle flow, and without magmatic inflation. We suggest that the Eastern Greater Antilles arc and comparable arcs are simply crustal-scale bivergent (or "doubly vergent") thrust wedges formed during unidirectional subduction. Sandbox kinematic modeling suggests, in addition, that a broad retrowedge containing an imbricate fan of thrusts develops only where the arc behaves relatively rigidly. In such cases, the arc acts as a backstop that transmits compressive stress into the backarc region. Further, modeling shows that when arcs behave as rigid blocks, the strike-slip component of oblique convergence is accommodated entirely within the prowedge and the arc—the retrowedge hosts only dip-slip faulting ("frontal thrusting"). The existence of large retrowedges and the distribution of faulting in an island arc may, therefore, be evidence that the arc is relatively rigid. The rigidity of an island arc may arise from its mafic composition and has implications for seismic-hazard analysis. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.