Structure, inferred mechanical properties, and implications for fluid transport in the décollement zone, Costa Rica convergent margin
2001-01-01

Research Article| October 01, 2001 Structure, inferred mechanical properties, and implications for fluid transport in the décollement zone, Costa Rica convergent margin Harold Tobin; Harold Tobin 1Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801, USA Search for other works by this author on: GSW Google Scholar Paola Vannucchi; Paola Vannucchi 2Dipartimento di Scienze della Terra, Università di Modena, Piazzale San Eufemia, 19, Modena, Italy Search for other works by this author on: GSW Google Scholar Martin Meschede Martin Meschede 3Institute of Geology, University of Tübingen, Tübingen, Germany Search for other works by this author on: GSW Google Scholar Geology (2001) 29 (10): 907–910. https://doi.org/10.1130/0091-7613(2001)029<0907:SIMPAI>2.0.CO;2 Article history received: 17 Jan 2001 rev-recd: 04 May 2001 accepted: 21 May 2001 first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Harold Tobin, Paola Vannucchi, Martin Meschede; Structure, inferred mechanical properties, and implications for fluid transport in the décollement zone, Costa Rica convergent margin. Geology 2001;; 29 (10): 907–910. doi: https://doi.org/10.1130/0091-7613(2001)029<0907:SIMPAI>2.0.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 Faults in a variety of tectonic settings can act as both conduits for and barriers to fluid flow, sometimes simultaneously. Documenting the interaction between hydrologic and tectonic processes in active faults in situ is the key to understanding their mechanical behavior and large-scale fluid transport properties. We present observations of the plate boundary décollement zone at the Middle America Trench off Costa Rica, showing that it is structurally divisible into an upper brittle-fracture–dominated domain overlying a lower, ductile domain. Pore-water geochemical evidence shows that along-fault flow is occurring specifically in the upper brittle domain, but is hydrologically isolated from fluids in the underlying footwall sediments. We propose a model for the mechanics of these contrasting domains in which differing stress paths coexist in the upper and lower parts of the décollement zone. The data suggest a mechanically controlled permeability anisotropy at a scale of several meters to ∼10 m across the décollement zone. This documentation of separate yet simultaneously active mechanical and hydrologic subregimes within a décollement provides a relatively simple explanation for enhanced along-fault permeability coexisting with reduced cross-fault permeability, without requiring matrix-scale permeability anisotropy. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.