Sunderland, E. Blanche; Morgan, Julia K. (2005): Microstructural variation in sediments from the toe of the Nankai accretionary prism; results of scanning electron microscope analysis. Texas A&M University, Ocean Drilling Program, College Station, TX, United States, In: Moore, Gregory F., Taira, Asahiko, Klaus, Adam, Becker, Keir, Becker, Luann, Boeckel, Babette, Cragg, Barry A., Dean, P. Allison, Fergusson, Christopher L., Henry, Pierre, Hirano, Satoshi, Hisamitsu, Toshio, Hunze, Sabine, Kastner, Miriam, Maltman, Alex J., Morgan, Julia K., Murakami, Yuki, Saffer, Demian M., Sanchez-Gomez, Mario, Screaton, Elizabeth J., Smith, David C., Spivack, Arthur J., Steurer, Joan F., Tobin, Harold J., Ujiie, Kohtaro, Underwood, Michael B., Wilson, Moyra E. J., Mikada, Hitoshi, Moore, J. Casey, Austin, Gary L., Bangs, Nathan L. B., Bourlange, Sylvain, Broilliard, Julien, Brueckmann, Warner, Corn, Ernest Ray, Davis, Earl E., Flemings, Peter B., Goldberg, David S., Gulick, Sean P. S., Hansen, Martin Bak, Hayward, Nathan, Hills, Denise J., Ienaga, Masanori, Ishiguro, Hiroyasu, Kinoshita, Masataka, Macdonald, Robert D., McNeill, Lisa, Obana, Shinichi, Hong, Ong Swee, Peacock, Sheila, Pettigrew, Thomas L., Saito, Saneatsu, Sawa, Takao, Thaiprasert, Nophawit, Tsurumi, Hikaru, Proceedings of the Ocean Drilling Program; scientific results; deformation and fluid flow processes in the Nankai Trough accretionary prism; coring, logging while drilling and advanced CORKs covering Legs 190 to 196 of the cruises of the drilling vessel JOIDES Resolution; Sydney, Australia, to Yokohama, Japan, Sites 1173-1178, 23 May-16 July 2000; and Keelung, Taiwan, to Kochi, Japan, Sites 808-1173, 2 May-1 July 2001, 190/196, georefid:2005-060943

Abstract:
Scanning electron microscope analyses of sediment samples collected from the frontal portion of the Nankai accretionary prism and Shikoku Basin during Ocean Drilling Program Leg 190 show systematic changes in clay microstructure and microfabric that correlate with depth, lithology, sediment deformation, and changing physical properties. Heterogeneous, open sediment textures found in the shallower lithologies, such as the upper Shikoku Basin facies, are characterized by random distributions of coarse particle aggregates and fine-grained clay minerals distributed throughout the matrix. The degree of clay mineral preferred orientation (CPO) generally increases with depth and adjacent to deformation structures but is retarded in an anomalous zone of high porosities at the reference Site 1173. Clay microstructures in and below the anomalous zone are very similar and provide little evidence that clays serve as the cementing agent. Deeper sediments, including most of the lower Shikoku Basin facies, exhibit more homogeneous distributions of dispersed and uniformly sized clay particles and commonly exhibit a high degree of CPO. The transition in texture appears to occur at the protodecollement horizon at the reference Site 1173 and slightly shallower in the section within the protothrust zone. The coincidence of this transition with noticeable downhole decreases in smectite abundance and compressional wave velocity (Vp) at Site 1173 highlight an important diagenetic boundary that may help to localize slip along the accretionary decollement as it propagates seaward.
Coverage:
West: 134.0000 East: 135.1500 North: 32.4500 South: 31.3000
Relations:
Expedition: 190
Supplemental Information:
Available only on CD-ROM in PDF format and on the Web in PDF or HTML
Data access:
Provider: SEDIS Publication Catalogue
Data set link: http://sedis.iodp.org/pub-catalogue/index.php?id=10.2973/odp.proc.sr.190196.212.2004 (c.f. for more detailed metadata)
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