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

July 10, 2017

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.

Citation Information

Publication Year 2017
Title The application of microtextural and heavy mineral analysis to discriminate between storm and tsunami deposits
DOI 10.1144/SP456.7
Authors Pedro J.M. Costa, Guy R. Gelfenbaum, Sue Dawson, Seanpaul La Selle, F Milne, J. Cascalho, C. Ponte Lira, C. Andrade, M. C. Freitas, Bruce E. Jaffe
Publication Type Article
Publication Subtype Journal Article
Series Title Geological Society, London, Special Publications
Index ID 70189298
Record Source USGS Publications Warehouse
USGS Organization Pacific Coastal and Marine Science Center