Journal Article

Present-day principal horizontal stress orientations in the Kumano forearc basin of the southwest Japan subduction zone determined from IODP NanTroSEIZE drilling Site C0009

Department of Geology and Geophysics [Laramie] ; University of Wyoming (UW), Institute of Geophysics [Taïwan] ; National Central University [Taiwan] (NCU), Byrne, Timothy B, Kameo, Koji, Centre Européen de Recherche et d'Enseignement des Géosciences de l'Environnement (CEREGE) ; Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Doan, Mai-Linh, Leibniz-Institut für Meereswissenschaften (IFM-GEOMAR), Buret, Christophe, Flemings, Peter, Schleicher, Anja M, Horiguchi, Keika, Laboratoire de Géophysique Interne et Tectonophysique (LGIT) ; Observatoire des Sciences de l'Univers de Grenoble (OSUG) ; Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national des sciences de l'Univers (INSU - CNRS)-In

2010

Overview

A 1.6 km riser borehole was drilled at site C0009 of the NanTroSEIZE, in the center of the Kumano forearc basin, as a landward extension of previous drilling in the southwest Japan Nankai subduction zone. We determined principal horizontal stress orientations from analyses of borehole breakouts and drilling-induced tensile fractures by using wireline logging formation microresistivity images and caliper data. The maximum horizontal stress orientation at C0009 is approximately parallel to the convergence vector between the Philippine Sea plate and Japan, showing a slight difference with the stress orientation which is perpendicular to the plate boundary at previous NanTroSEIZE sites C0001, C0004 and C0006 but orthogonal to the stress orientation at site C0002, which is also in the Kumano forearc basin. These data show that horizontal stress orientations are not uniform in the forearc basin within the surveyed depth range and suggest that oblique plate motion is being partitioned into strike-slip and thrusting. In addition, the stress orientations at site C0009 rotate clockwise from basin sediments into the underlying accretionary prism.

• Publisher: American Geophysical Union,CCSD,Blackwell Publishing Ltd,John Wiley & Sons, Inc
• Subject: Basins / Boreholes / Drilling / Earth Sciences / Earth, ocean, space / Environmental Sciences / Exact sciences and technology / Geophysics / Global Changes / Horizontal / IODP / Kumano Forearc Basin / NanTroSEIZE / Orientation / Physics / Plate tectonics / Sciences of the Universe / Seismology / Southwest / stress orientation / Stresses