Forearc response to subduction of the Cocos Ridge, Panama-Costa Rica

Abstract

Research Article| May 01, 1990 Forearc response to subduction of the Cocos Ridge, Panama-Costa Rica JEFF CORRIGAN; JEFF CORRIGAN 1Department of Geological Sciences, University of Texas at Austin, Austin, Texas 78713 Search for other works by this author on: GSW Google Scholar PAUL MANN; PAUL MANN 2Institute for Geophysics, University of Texas at Austin, 8701 Mopac Boulevard, Austin, Texas 78759 Search for other works by this author on: GSW Google Scholar JAMES C. INGLE, JR. JAMES C. INGLE, JR. 3Department of Geology, Stanford University, Stanford, California 94305 Search for other works by this author on: GSW Google Scholar Author and Article Information JEFF CORRIGAN 1Department of Geological Sciences, University of Texas at Austin, Austin, Texas 78713 PAUL MANN 2Institute for Geophysics, University of Texas at Austin, 8701 Mopac Boulevard, Austin, Texas 78759 JAMES C. INGLE, JR. 3Department of Geology, Stanford University, Stanford, California 94305 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1990) 102 (5): 628–652. https://doi.org/10.1130/0016-7606(1990)102<0628:FRTSOT>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation JEFF CORRIGAN, PAUL MANN, JAMES C. INGLE; Forearc response to subduction of the Cocos Ridge, Panama-Costa Rica. GSA Bulletin 1990;; 102 (5): 628–652. doi: https://doi.org/10.1130/0016-7606(1990)102<0628:FRTSOT>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 SocietyGSA Bulletin Search Advanced Search Abstract Stratigraphic, paleontologic, and structural data from two Panama-Costa Rica forearc peninsulas located landward of the aseismic Cocos Ridge along the southernmost Middle America Trench document rapid Pliocene subsidence and basin infilling followed by Quaternary deformation and uplift. On the Burica Peninsula, an approximately 3,000-m-thick, Pliocene-Pleistocene clastic sedimentary sequence, characterized by fine-grained turbidite deposits and volumetrically minor coarser-grained channel-fill, slump, and debris-flow deposits, bears depth-diagnostic foraminifera that document rapid Pliocene subsidence and deposition on a south-dipping paleoslope. New paleobathymetric and age estimates from foraminifera in these rocks indicate shallowing of depositional paleodepths from 2,000+ to 1,200 m during the late Pliocene. Present-day exposure of these rocks indicates an average Quaternary uplift rate of ∼1 mm/yr. The turbidite section on the Burica Peninsula is interpreted to represent a trench-slope deposit and is correlated to a similar, marine sedimentary section on the adjacent Osa Peninsula of Costa Rica.Structures developed within Pliocene-Pleistocene strata of the outer-forearc Burica and Osa Peninsulas record minor (<5%) subhorizontal, margin-perpendicular shortening and margin-perpendicular extension. Bedding orientations on the Osa and Burica Peninsulas generally record arcward tilting by 10°-30° of these outer-forearc blocks. On the Burica Peninsula, the Medial fault zone, a north-striking, high-angle, right-lateral strike-slip (?) fault, has truncated and reoriented the Pliocene-Pleistocene sedimentary sequence by fault-bend (forced) folding. A linear, margin-parallel fault, herein named the "Ballena-Celmira fault zone," bounds the arcward side of the Osa and Burica Peninsulas and has accommodated vertical displacements between the outer forearc (Burica-Osa area) and inner forearc (Terraba area) throughout the Tertiary. Structural and seismicity observations from the forearc region suggest that Neogene deformation of the leading edge of the arc in this area reflects the effects of isostatic uplift, and possibly increased interplate shear stresses, as a result of subduction of the Cocos Ridge beneath this part of the arc since 1 m.y. ago. 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.