Yamada, Yasuhiro et al. (2011): Structural styles across the Nankai accretionary prism revealed from LWD borehole images and their correlation with seismic profile and core data; results from NanTroSEIZE Stage 1 expeditions

Leg/Site/Hole:
ODP 188
ODP 204
Identifier:
2013-046513
georefid

10.1029/2010GC003365
doi

Creator:
Yamada, Yasuhiro
Kyoto University, Department of Earth Resources Engineering, Kyoto, Japan
author

McNeill, Lisa C.
University of Southampton, United Kingdom
author

Moore, J. Casey
University of California at Santa Cruz, United States
author

Nakamura, Yasuyuki
University of Tokyo, Japan
author

Identification:
Structural styles across the Nankai accretionary prism revealed from LWD borehole images and their correlation with seismic profile and core data; results from NanTroSEIZE Stage 1 expeditions
2011
Geochemistry, Geophysics, Geosystems - G (super 3)
American Geophysical Union and The Geochemical Society, United States
12
Four drill sites of IODP NanTroSEIZE Stage 1 Expedition transected the Nankai Trough, offshore SW Japan, from the deformation front to the Kumano fore-arc basin. Borehole resistivity images from the logging-while-drilling (LWD) data were analyzed to extract orientations of faults, fractures, and bedding planes to examine the structural styles. On the basis of these features, drilling intervals were classified into fore-arc basin deposits, surface slope sediments, and deformed accretionary wedge, and these can be compared with characteristics from seismic profiles and core structural data. Bedding orientations identified in these three data sets are generally comparable, but the difference in resolution between the data sets produces different results in interpretation where geology is highly deformed or includes finer internal structures. Faults can also be correlated between these three data sets, but the differences in their appearance require special attention for accurate correlation. Many faults imaged in seismic profiles actually consist of microfracture systems, as shown in cores, that can also be identified in borehole images. Some clear faults in seismic profiles cannot be identified in borehole images, probably because of their minimal resistivity contrast with the surrounding rocks or a more complex fault zone at the borehole scale. These results suggest that these three data sets can be used to extract not only the general structure but also different styles of deformation at different scales from core samples (mm to cm), to LWD (mm to 10 m), to seismic (10 m to tens of km). This correlation requires a deep understanding of the resolution and shortcomings of each methodology.
Coverage:Geographic coordinates:
North:35.0000
West:135.0000East: 139.0000
South:-33.1800

Structural geology; Applied geophysics; accretionary wedges; basins; bedding; boreholes; cores; East Pacific; faults; folds; fore-arc basins; fractures; geophysical methods; geophysical profiles; geophysical surveys; imagery; Integrated Ocean Drilling Program; IODP Site C0001; IODP Site C0002; Kumano Basin; Leg 188; Leg 204; marine geology; measurement-while-drilling; Nankai Trough; NanTroSEIZE; North Pacific; Northeast Pacific; Northwest Pacific; Ocean Drilling Program; Pacific Ocean; planar bedding structures; preferred orientation; sedimentary structures; seismic methods; seismic profiles; Southern Ocean; structural analysis; style; subduction zones; surveys; well-logging; West Pacific;

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