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Microfabric of Altered Ash Layers, ODP Leg 131, Nankai Trough

Published online by Cambridge University Press:  28 February 2024

Jane S. Tribble  and
Roy H. Wilkens
Jane S. Tribble
Affiliation:
Department of Oceanography, Honolulu, Hawaii 96822
Roy H. Wilkens
Affiliation:
Hawaii Institute of Geophysics, School of Ocean and Earth Science and Technology, University of Hawaii, Honolulu, Hawaii 96822
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Abstract

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Samples of ash layers and associated background sediments from Site 808 of ODP Leg 131 in the Nankai Trough accretionary prism were analyzed for changes in mineralogy, porosity and micro-fabric associated with alteration of volcanic ash. Ash layers range from incipient stages of alteration and dissolution to complete alteration to clay minerals and clinoptilolite. Ash layers contain greater abundances of total clay minerals and lower percentages of quartz than do surrounding background hemipelagic sediments. The clay-sized fraction of ash layers is dominated by pure dioctahedral smectite, whereas the background sediments contain primarily illite and chlorite with minor amounts of smectite. Analysis of microfabric revealed dramatic changes in the distributions and abundances of grains and pores during ash alteration. The relative abundances of large pores, grains, and matrix material were quantified on digital back-scattered electron images (BSEI) of ash layer and background sediment samples. During burial, the abundant glass shards of shallow ash layers are initially altered, presumably to smectite. Subsequent dissolution of the glass leaves open, shard-shaped pores, resulting in increased porosities. With greater burial, these pores are filled with clinoptilolite. Although the presence of ash and its alteration products clearly influences sediment physical properties, there is no apparent correlation of the abundance of ash or its alteration products with the formation of thrust faults or other structures within the Nankai Trough accretionary prism.

Keywords

Accretionary prismAlterationAshMicrofabricNankai TroughPhysical propertiesPorosity
Type
Research Article
Information
Clays and Clay Minerals , Volume 42 , Issue 4 , August 1994 , pp. 428 - 436
Copyright
Copyright © 1994, Clay Minerals Society

References

Bird, P., (1984) Hydration-phase diagrams and friction of montmorillonjte under laboratory and geologic conditions, with implications for shale compaction, slope stability, and strength of fault gauge: Tectonophys. 107, 235–260.CrossRefGoogle Scholar
Bruce, C. H., (1984) Smectite dehydration—Its relation to structural development and hydrocarbon accumulation in Northern Gulf of Mexico basin: Bull. Am. Assoc. Petr. Geol. 68, 673–683.Google Scholar
Burst, J. R. Jr. 1969() Diagenesis of Gulf Coast clay sediments and its possible relationships to petroleum migration: Bull. Am. Assoc. Petr. Geol. 53, 73–93.Google Scholar
Gieskes, J. M., (1983) The chemistry of interstitial waters of deep sea sediments: Interpretation of Deep Sea Drilling data: in Chemical Oceanography 8, Riley, J. P., and Chester, R., eds., Academic Press, New York, 221–269.CrossRefGoogle Scholar
Hanshaw, B. B., and Bredehoeft, J. D., (1968) On the maintenance of anomalous fluid pressures II; source layer at depth: Geol. Soc. Am. Bull. 79, 1107–1122.CrossRefGoogle Scholar
Hein, J. R., and Scholl, D. W., (1978) Diagenesis and distribution of late Cenozoic volcanic sediment in the southern Bering Sea: Geol. Soc. Am. Bull. 89, 197–210.2.0.CO;2>CrossRefGoogle Scholar
Hodder, A. P. W., Naish, T. R., and Nelson, C. S., (1993) A two-stage model for the formation of smectite from detrital volcanic glass under shallow-marine conditions: Mar. Geol. 109, 279–285.CrossRefGoogle Scholar
Karlak, R. F., and Burnett, D. S., (1966) Quantitative phase analysis by X-ray diffraction: Anal. Chem. 38, 1741–1745.CrossRefGoogle ScholarPubMed
Kastner, M., and Stonecipher, S. A., (1978) Zeolites in pelagic sediments of the Atlantic, Pacific, and Indian Oceans: in Natural Zeolites, Occurrence, Properties, Use, Sand, L. B., and Mumpton, F. A., eds., Pergamon Press, New York, 199–220.Google Scholar
Magara, K., (1975) Reevaluation of montmorillonite dehydration as cause of abnormal pressure and hydrocarbon migration: Bull. Am. Assoc. Petr. Geol. 59, 292–302.Google Scholar
Moore, D., and Reynolds, R., (1989) X-Ray Diffraction and the Identification and Analysis of Clay Minerals: Oxford University Press, New York, 332 pp.Google Scholar
Olafsson, G., (1993) Calcareous nannofossil biostratigraphy of the Nankai Trough: in Proc. ODP, Sci. Results, 131, Hill, I. A., Taira, A., Firth, J. V., et al., eds., Ocean Drilling Program, College Station, Texas, 3–13.Google Scholar
Russ, J. C., (1990) Computer-Assisted Microscopy: Plenum Press, New York, 453 pp.CrossRefGoogle Scholar
Taira, A., Hill, I., and Firth, J. V., (1991) Proc. ODP, Init. Repts., 131, Ocean Drilling Program, College Station, Texas 434 pp.Google Scholar
Tribble, J. S., (1990) Clay diagenesis in the Barbados accretionary complex: Potential impact on hydrology and subduction dynamics: in Proc. ODP, Sci. Res., 110, Moore, J. C., Mascle, A., et al., eds., Ocean Drilling Program, College Station, Texas, 97–110.Google Scholar
Tribble, J. S., Wilkens, R. H., and Sasaki, S., (1993) Changes in microfabric associated with alteration of volcanic ash: A comparison of the Nankai Trough, Hawaiian Arch, and Barbados accetionary complex: EOS 74, 226.Google Scholar
Underwood, M., Orr, R., Pickering, K., and Taira, A., (1993) Provenance and dispersal patterns for sediments in the turbidite wedge of Nankai Trough: in Proc. ODP, Sci. Results, 131, Hill, I. A., Taira, A., Firth, J. V., et al., eds., Ocean Drilling Program, College Station, Texas, 15–33.Google Scholar
Wilkens, R. H., McClellan, P., Moran, K., Tribble, J. S., Taylor, E., and Verduzco, E., (1990) Diagenesis and dewatering of clay-rich sediments, Barbados accretionary prism: in Proc. ODP, Sci. Res., 110, Moore, J. C., Mascle, A., et al., eds., Ocean Drilling Program, College Station, Texas, 309–320.Google Scholar