TY - JOUR
T1 - Interactions between deformation and fluids in the frontal thrust region of the NanTroSEIZE transect offshore the Kii Peninsula, Japan
T2 - Results from IODP Expedition 316 Sites C0006 and C0007
AU - Screaton, E.
AU - Kimura, G.
AU - Curewitz, D.
AU - Moore, G.
AU - Chester, F.
AU - Fabbri, O.
AU - Fergusson, C.
AU - Girault, F.
AU - Goldsby, D.
AU - Inagaki, F.
AU - Jiang, T.
AU - Kitamura, Y.
AU - Knuth, M.
AU - Li, C.-F.
AU - Claesson Liljedahl, L.
AU - Louis, L.
AU - Miuiken, K.
AU - Nicholson, Uisdean
AU - Riedinger, N.
AU - Sakaguchi, A.
AU - Solomon, E.
AU - Strasser, M.
AU - Su., X.
AU - Tsutsumi, A.
AU - Yamaguchi, A.
AU - Ujiee, K.
AU - Zhao, X.
PY - 2009/12
Y1 - 2009/12
N2 - [i] Integrated Ocean Drilling Program (IODP) Expedition 316 Sites C0006 and C0007 examined the deformation front of the Nankai accretionary prism offshore the Kii Peninsula, Japan. In the drilling area, the frontal thrust shows unusual behavior as compared to other regions of the Nankai Trough. Drilling results, integrated with observations from seismic reflection profiles, suggest that the frontal thrust has been active since 0.78-0.436 Ma and accommodated ∼13 to 34% of the estimated plate convergence during that time. The remainder has likely been distributed among out-of-sequence thrusts further landward and/or accommodated through diffuse shortening. Unlike results of previous drilling on the Nankai margin, porosity data provide no indication of undercompaction beneath thrust faults. Furthermore, pore water geochemistry data lack clear indicators of fluid flow from depth. These differences may be related to coarser material with higher permeability or more complex patterns of faulting that could potentially provide more avenues for fluid escape. In turn, fluid pressures may affect deformation. Well-drained, sand-rich material under the frontal thrust could have increased fault strength and helped to maintain a large taper angle near the toe. Recent resumption of normal frontal imbrication is inferred from seismic reflection data. Associated décollement propagation into weaker sediments at depth may help explain evidence for recent slope failures within the frontal thrust region. This evidence consists of seafloor bathymetry, normal faults documented in cores, and low porosities in near surface sediments that suggest removal of overlying material. Overall, results provide insight into the complex interactions between incoming materials, deformation, and fluids in the frontal thrust region. subduction zone; Nankai; fluid flow; frontal thrust; IODP; seamount.
AB - [i] Integrated Ocean Drilling Program (IODP) Expedition 316 Sites C0006 and C0007 examined the deformation front of the Nankai accretionary prism offshore the Kii Peninsula, Japan. In the drilling area, the frontal thrust shows unusual behavior as compared to other regions of the Nankai Trough. Drilling results, integrated with observations from seismic reflection profiles, suggest that the frontal thrust has been active since 0.78-0.436 Ma and accommodated ∼13 to 34% of the estimated plate convergence during that time. The remainder has likely been distributed among out-of-sequence thrusts further landward and/or accommodated through diffuse shortening. Unlike results of previous drilling on the Nankai margin, porosity data provide no indication of undercompaction beneath thrust faults. Furthermore, pore water geochemistry data lack clear indicators of fluid flow from depth. These differences may be related to coarser material with higher permeability or more complex patterns of faulting that could potentially provide more avenues for fluid escape. In turn, fluid pressures may affect deformation. Well-drained, sand-rich material under the frontal thrust could have increased fault strength and helped to maintain a large taper angle near the toe. Recent resumption of normal frontal imbrication is inferred from seismic reflection data. Associated décollement propagation into weaker sediments at depth may help explain evidence for recent slope failures within the frontal thrust region. This evidence consists of seafloor bathymetry, normal faults documented in cores, and low porosities in near surface sediments that suggest removal of overlying material. Overall, results provide insight into the complex interactions between incoming materials, deformation, and fluids in the frontal thrust region. subduction zone; Nankai; fluid flow; frontal thrust; IODP; seamount.
UR - http://www.scopus.com/inward/record.url?scp=76149139775&partnerID=8YFLogxK
U2 - 10.1029/2009GC002713
DO - 10.1029/2009GC002713
M3 - Article
AN - SCOPUS:76149139775
SN - 1525-2027
VL - 10
JO - Geochemistry, Geophysics, Geosystems
JF - Geochemistry, Geophysics, Geosystems
IS - 12
M1 - Q0AD01
ER -