Please use this identifier to cite or link to this item: http://hdl.handle.net/1822/50792

TitleAnalysis of spectra from portable handheld gamma-ray spectrometry for terrain comparative assessment
Author(s)Dias, Flávio
Lima, Marco
Sanjurjo-Sánchez, Jorge
Alves, C.
KeywordsNatural radioactivity
Geological hazards
Site investigation
Granite rocks
Metaclastic rocks
Issue date2016
PublisherElsevier Ltd
JournalJournal of Environmental Radioactivity
Abstract(s)Geological characteristics can have impacts on societal development by, e.g., geotechnical issues and radiological hazard levels. Due to urban sprawl, there is an increasing need for detailed geological assessment. In this work are analysed data from portable handheld gamma-ray spectra (K, eU and eTh) obtained in granitic and Silurian metaclastic outcrops as well as in an profile, roughly N-S, o n soil covered terrains transecting a mapped contact between these rock types (the profile's northern extremity is at locations mapped as granite). Estimations from gamma-ray spectra were studied by univariate and multivariate analyses. K, eU and eTh values were higher on granite in relation to Silurian metaclastic rocks. The northern extremity of the profile showed clearly higher contents of eTh and this contrast was supported by univariate statistical tools (normality plot and Wilk-Shapiro test; boxplots). A ternary plot with the contribution of the elements to gamma-ray absorbed dose showed the separation of granite from Silurian metaclastic rocks with the former being nearer the eTh vertex. The points in the northern extremity of the profile are nearer the eTh vertex than the other points on the profile. These visual suggestions were supported by hierarchical cluster analysis, which was able to differentiate between granite and metaclastic outcrops and separate portions of the profile located on different terrains. Portable gamma-ray spectrometry showed, hence, the potential to distinguish granite and metaclastic terrains at a scale useful for engineering works. These results can also be useful for a first comparative zoning of radiological hazards (which are higher for granite).
TypeArticle
URIhttp://hdl.handle.net/1822/50792
DOI10.1016/j.jenvrad.2016.01.017
ISSN0265-931X
Publisher versionhttps://www.sciencedirect.com/science/article/pii/S0265931X16300170
Peer-Reviewedyes
AccessRestricted access (UMinho)
Appears in Collections:CIG-R - Artigos (Papers)

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