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The separation of multi-element spatial patterns in till geochemistry of southeastern Sweden combining GIS, principal component analysis and high-dimensional visualization
KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
2007 (English)In: Geochemistry: Exploration, Environment, Analysis, ISSN 1467-7873, Vol. 7, no 4, 303-318 p.Article in journal (Refereed) Published
Abstract [en]

The chemical composition of glacial till is a product of parentrocks, glacial and post-glacial processes and reflects the geogenicvariation of chemical elements. Contrasting chemical compositionof rock types together with spatial variation in distributionpatterns of metals in the fine fraction of till in southeasternSweden assists in the identification of the signatures reflectingparent rocks in glacial till samples. The spatial patterns ofCu, Co, Ni, Pb, V and Zn in 1411 till samples were presentedby point symbol maps, followed by the extraction of multi-elementassociations by employing principal component analysis (PCA)and interactive high-dimensional visualization. The most influentialmulti-element spatial patterns in till data could be separatedusing either the numerical (PCA) or the visual approach. However,more information was extracted by combining the two techniques.In addition, interactive visualization provided an objectivepresentation of complex information in sparse lithogeochemicaldata. The study resulted in new knowledge about the naturalvariation of the levels of six elements in till, and a graphicalpresentation to convey information about and compare multi-elementgeochemical signatures.

Place, publisher, year, edition, pages
2007. Vol. 7, no 4, 303-318 p.
Keyword [en]
Multi-element spatial patterns, Southeastern Sweden, Till geochemistry, Visualization
National Category
Engineering and Technology
URN: urn:nbn:se:kth:diva-5030DOI: 10.1144/1467-7873/06-117ISI: 000250859200003ScopusID: 2-s2.0-36148937858OAI: diva2:7637
QC 20100609Available from: 2005-04-18 Created: 2005-04-18 Last updated: 2011-11-03Bibliographically approved
In thesis
1. Visualization, integration and analysis of multi-element geochemical data
Open this publication in new window or tab >>Visualization, integration and analysis of multi-element geochemical data
2005 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

generated large databases containing information on the concentrations of chemical elements in rocks, surface sediments and biogeochemical materials. Regional geochemical data being imprecise, multivariate, spatially auto-correlated and non-normally distributed pose specific problems to the choice of data analysis methods. Commonly several methods are combined, and the choice of techniques depends on the characteristics of data as well as the purpose of study. One critical issue is dealing with extreme data values (or outliers) in the initial stages of analysis. Another common problem is that integrated analysis of several geochemical datasets is not possible without interpolating the point data into surfaces. Finally, separation of anthropogenic influences from natural geochemical background in the surface materials is an issue of great importance for environmental studies.

This study describes an approach to address the above-mentioned problems by a flexible combination and use of GIS and multivariate statistical techniques with high-dimensional visualization. Dynamically linked parallel coordinate and scatterplot matrix display techniques allow simultaneous presentation of spatial, multi-element and qualitative information components of geochemical data. The plots not only display data in multi-dimensional space, but also allow detailed inspection of the data with interactive multi-dimensional brushing tools. The results of the study indicate that these simple high-dimensional visualization techniques can successfully complement the traditional statistical and GIS analysis in all steps of data processing, from data description and outlier identification through data integration, analysis, validation, and presentation of results. The outcomes of the study include: a visual procedure towards intelligent data cleaning where potentially significant information in very high element concentrations is preserved, methods for integration and visual analysis of geochemical datasets collected in different grids, estimation of geochemical baseline concentrations of trace metals in till geochemistry of southeastern Sweden, use of multi-element spatial fingerprints to trace natural geochemical patterns in biogeochemistry, and a new graphical approach to present multi-element geochemical data summaries and results from numerical analysis.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005
Trita-LWR. PHD, ISSN 1650-8602 ; 1018
Earth sciences, GIS, interactive visualization, glacial till, biogeochemistry, metals, southeastern Sweden, Geovetenskap
National Category
Earth and Related Environmental Sciences
urn:nbn:se:kth:diva-169 (URN)91-7178-014-9 (ISBN)
Public defence
2005-04-21, Kollegiesalen, Valhallavägen 79, Stockholm, 10:00
QC 20100609Available from: 2005-04-18 Created: 2005-04-18 Last updated: 2010-06-09Bibliographically approved

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