HR: 1330h
AN: T42D-0967
TI: Integration of Leg 196 LWD data and 3-D seismic data in the Nankai accretionary prism: Preliminary interpretations of fluid flow indicators
AU: * Gulick, S P
EM: sean@utig.ig.utexas.edu
AF: University of Texas, Institute for Geophysics, 4412 Spicewood Springs Rd., Austin, TX 78759 United States
AU: Bangs, N L
AF: University of Texas, Institute for Geophysics, 4412 Spicewood Springs Rd., Austin, TX 78759 United States
AU: Shipley, T H
AF: University of Texas, Institute for Geophysics, 4412 Spicewood Springs Rd., Austin, TX 78759 United States
AU: Moore, G F
AF: Department of Geology and Geophysics, Univ. of Hawaii, 1680 East-West Rd., Post 813, Honolulu, HI 96822 United States
AU: Kuramoto, S
AF: Geological Survey of Japan, 1-1-3 Higashi, Tsukuba, 305-8537 Japan
AB: Leg 196 of the Ocean Drilling Program (ODP) investigated the interrelationship between the fluid flow regime and deformation in the Nankai Trough accretionary prism. Leg 196 is part of a larger effort to fully characterize the accretionary processes at the Nankai trough that also includes ODP Legs 131 and 190 and a 3-D seismic reflection survey. Logging-while-drilling (LWD) data from Site 808, collected during Leg 196, combined with wireline and core data from Site 1174, collected during Leg 190 provide details about fluid expulsion, deformation, diagenesis, and compaction at both the proto-thrust and frontal thrust of the Nankai accretionary prism. These data can be used to calibrate the 3-D seismic reflection data. At Site 808, a clear negative-polarity reflection is present, while at Site 1174 there is no fault-plane reflection, making these sites useful end-member cases for modeling. Seismic modeling at these sites seeks to differentiate between reflection polarity caused by differences in consolidation of the overthrust and underthrust sections and the presence of fault-channelized fluids. Preliminary interpretations of the first three thrust faults of the accretionary prism show consistent negative polarity fault plane reflections with a concentration of high amplitudes where each of the three faults roll over to diminish in dip towards the seafloor. To interpret fault zone reflections as fluid indicators, we present seismic modeling results of the physical causes of these variable thrust fault images at the deformation front. In addition, we present 3-D impedance surfaces for the remaining thrust faults, from the deformation front to the first out-of-sequence thrust that we examine for fluid flow indicators based on the LWD-seismic integration at Sites 808 and 1174.
DE: 3025 Marine seismics (0935)
DE: 5104 Fracture and flow
DE: 8010 Fractures and faults
DE: 8045 Role of fluids
SC: T
MN: 2001 AGU Fall Meeting