The application of microtextural and heavy mineral analysis to discriminate between storm and tsunami deposits

Pedro J.M. Costa, G. Gelfenbaum, S. Dawson, S. La Selle, F. Milne, J. Cascalho, C. Ponte Lira, C. Andrade, M. C. Freitas, B. Jaffe

    Research output: Chapter in Book/Report/Conference proceedingChapter

    20 Citations (Scopus)

    Abstract

    Recent work has applied microtextural and heavy mineral analyses to sandy storm and tsunami deposits from Portugal, Scotland, Indonesia and the USA. We looked at the interpretation of microtextural imagery (scanning electron microscopy) of quartz grains and heavy mineral compositions. We consider inundation events of different chronologies and sources (the AD 1755 Lisbon and 2004 Indian Ocean tsunamis, the Great Storm of 11 January 2005 in Scotland, and Hurricane Sandy in 2012) that affected contrasting coastal and hinterland settings with different regional oceanographic conditions. Storm and tsunami deposits were examined along with potential source sediments (alluvial, beach, dune and nearshore sediments) to determine provenance. Results suggest that tsunami deposits typically exhibit a significant spatial variation in grain sizes, microtextures and heavy minerals. Storm deposits show less variability, especially in vertical profiles. Tsunami and storm quartz grains had more percussion marks and fresh surfaces compared to potential source material. Moreover, in the studied cases, tsunami samples had fewer fresh surfaces than storm deposits. Heavy mineral assemblages are typically site-specific. The concentration of heavy minerals decreases upwards in tsunamigenic units, whereas storm sediments show cyclic concentrations of heavy minerals, reflected in the laminations observed macroscopically in the deposits.

    Original languageEnglish
    Title of host publicationTsunamis
    Subtitle of host publicationGeology, Hazards and Risks
    EditorsE. M. Scourse, N. A. Chapman, D. R. Tappin, S. R. Wallis
    PublisherGeological Society of London
    Pages167-190
    Number of pages24
    Volume456
    Edition1
    ISBN (Print)9781786203182
    DOIs
    Publication statusPublished - Feb 2017

    Publication series

    NameGeological Society Special Publication
    Number1
    Volume456
    ISSN (Print)0305-8719

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