Porosity loss within the underthrust sediments of the Nankai accretionary complex: Implications for overpressures

Research Article| January 01, 2002 Porosity loss within the underthrust sediments of the Nankai accretionary complex: Implications for overpressures Elizabeth Screaton; Elizabeth Screaton 1Department of Geological Sciences, University of Florida, Gainesville, Florida 32611, USA Search for other works by this author on: GSW Google Scholar Demian Saffer; Demian Saffer 2Department of Geology and Geophysics, University of Wyoming, Laramie, Wyoming 82071-3006, USA Search for other works by this author on: GSW Google Scholar Pierre Henry; Pierre Henry 3Département de Géologie, École Normale Supérieure, Paris Cedex 05 75231, France Search for other works by this author on: GSW Google Scholar Sabine Hunze Sabine Hunze 4Geowissenschaftliche Gemeinschaftsaufgaben-GGA, Stilleweg 2, 30631 Hannover, Germany Leg 190 Shipboard Scientific Party101 Search for other works by this author on: GSW Google Scholar Author and Article Information Elizabeth Screaton 1Department of Geological Sciences, University of Florida, Gainesville, Florida 32611, USA Demian Saffer 2Department of Geology and Geophysics, University of Wyoming, Laramie, Wyoming 82071-3006, USA Pierre Henry 3Département de Géologie, École Normale Supérieure, Paris Cedex 05 75231, France Sabine Hunze 4Geowissenschaftliche Gemeinschaftsaufgaben-GGA, Stilleweg 2, 30631 Hannover, Germany Leg 190 Shipboard Scientific Party101 Publisher: Geological Society of America Received: 23 Apr 2001 Revision Received: 25 Jul 2001 Accepted: 20 Aug 2001 First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2002) 30 (1): 19–22. https://doi.org/10.1130/0091-7613(2002)0302.0.CO;2 Article history Received: 23 Apr 2001 Revision Received: 25 Jul 2001 Accepted: 20 Aug 2001 First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Elizabeth Screaton, Demian Saffer, Pierre Henry, Sabine Hunze; Porosity loss within the underthrust sediments of the Nankai accretionary complex: Implications for overpressures. Geology 2002;; 30 (1): 19–22. doi: https://doi.org/10.1130/0091-7613(2002)0302.0.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 Subduction complexes provide an opportunity to examine the interactions of deformation and fluid flow in an active setting. Ocean Drilling Program Leg 190 investigated the relationship between deformation, physical properties, and fluid flow in the toe of the Nankai Trough accretionary complex. With three sites (two from Leg 190, one from a previous leg) penetrating the décollement zone at various stages of development along the same transect, it is now possible to examine the change in porosity during rapid loading by trench turbidites and subsequent underthrusting. Results indicate inhibited dewatering and probable overpressure development seaward of the frontal thrust. Comparison of a reference site porosity versus depth curve to data from a site located within the protothrust zone indicates an overpressure ratio, λ*, of ∼0.42, where λ* = (pore pressure − hydrostatic pressure)/(lithostatic pressure − hydrostatic pressure). These overpressures suggest that the hemipelagic sediments have insufficient permeability for fluid escape to keep pace with the rapid loading by turbidite deposition within the trench. At a site 1.75 km farther arcward, an excess pore pressure ratio of λ* = ∼0.47 was estimated, reflecting the additional loading due to recent thickening by the frontal thrust. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.