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INTRODUCTION TO PART 2 OF THE GEOCHEMICAL ATLAS OF EUROPE

W. De Vos¹ and T. Tarvainen²

¹Geological Survey of Belgium, Brussels, Belgium ²Geological Survey of Finland, Espoo, Finland

A comprehensive introduction giving the background to the FOREGS-EuroGeoSurveys Geochemical Baseline Mapping Programme is presented by R. Salminen, A. Demetriades and S. Reeder in Part 1. Given the recent merger of FOREGS into the new structure EuroGeoSurveys, its President, Ch. Tsoutrelis, contributed a foreword to this second volume.

Part 2 of the Geochemical Atlas of Europe cannot be understood without consulting Part 1, which shows all the geochemical maps of Europe. The main purpose of Part 2 is to describe and try to understand the geochemical patterns of Europe which are apparent for the first time at the scale of the continent. Considerable effort was put in meetings with specialists from the Geological Surveys in order to reach a scientific agreement on what the patterns mean at the local, regional and continental scale. The meetings were either plenary or in subgroups, subdivided according to the discussed sample medium. The results are published here as seven texts which are interwoven as they progress through the alphabetical order of the elements, in parallel with the layout of Part 1. This is further explained in the General Introduction and Structure of the Interpretation text.

A general introduction to the chemistry and geochemistry of the elements is presented by S. Reeder, H. Taylor, R.A. Shaw and A. Demetriades, to be used as background information in understanding the natural behaviour of the different elements studied in the present project.

The distribution of elements in subsoil and topsoil is discussed by W. De Vos et al., followed by the distribution in humus by W. De Vos et al., in stream water by B. De Vivo et al., in stream sediment by W. De Vos et al., and in floodplain sediment by A. Demetriades et al. Finally for each element there is a section on Comparison of the elements in all sample media.

After the introduction to each of these sections, the discussion of every element follows in the order which is also used in Part 1, for easy reference. This forms the main body of the interpretation of Part 2. Tables with statistics comparing the FOREGS samples with other reference data at continental or global scales are added for most elements. Also boxplots illustrating the variance in soils and sediments are added, as well as scattergrams showing the correlation between typical elements in soil or sediment. Other relevant figures and tables are integrated in the text. After the elemental descriptions, there is a final section with Discussion and Conclusions, written by T. Tarvainen, W. De Vos and A. Demetriades.

A series of new maps referred to in Part 2 are presented after the main interpretation text and its list of references. They include ratio maps of topsoil compared to subsoil for the elements Ca, Cd, Cu, Eu, Hg, Mg, Mn, P, Pb, S, Sb, Sr. These are all discussed in the soil text. In addition, there is a map showing the dominant land use of the areas where samples were taken, one on the weathering index in topsoil, and a mineral deposits map of Europe showing important localities referred to in the text, especially in the floodplain descriptions, as possible sources of metal enrichment.

Five annexed publications discuss themes related to the main element-by-element interpretation. The first one, by E.L. Ander, B. Smith, and S. Reeder, called “Thematic interpretation of stream water chemistry” complements the interpretation of the spatial analysis of the distribution patterns, and constitutes a highly instructive addition to the interpretation text of stream water.

A text by J. Lis and A. Pasieczna discusses a comparison of the new European mapping with a geochemical mapping carried out in Poland ten years ago, generally confirming the validity of the low-density results from the FOREGS approach. A second text by the same authors presents some geochemical characteristics of the glacial drift area of the northern European plain.

A factor analysis interpretation of European stream water data is presented by S. Pirc, S. Albanese, B. De Vivo and W. De Vos. And a factor analysis interpretation of European soil, stream and floodplain sediment data, i.e., the solid sample media, is discussed by M.J. Batista, A. Demetriades, S. Pirc, W. De Vos, M. Bidovec and L. Martins.

In Annex 6 at the back of the volume, some corrected maps are to be found, which had errata in Part 1 (Hg for humus, I and K for stream water, and Cs, Ce and Ti for floodplain sediment), followed by new stream sediment maps completed with the data on Sweden unavailable at the time of publication of Part 1 in 2005, and some maps that needed small corrections they will be found after the main text.

General introduction and structure of the interpretation text

The main body of Part 2 of the FOREGS Geochemical Atlas of Europe is concerned with the interpretation of the geochemical distribution maps for each element or determinand, in the order adopted in Part 1 (Salminen et al. 2005). This interpretation is by no means exhaustive. It is the first attempt to understand and interpret a very large dataset, characterising the geochemistry of the surface environment of most of western and central Europe. The project was indeed supported and carried out by the national geological surveys of 25 countries and three Italian universities.

The homogeneous dataset and the geochemical distribution maps are made available to all scientists, who are free to contribute their own interpretation of the provided data. As geoscientists, it is our duty to provide a first interpretation based mainly on the geology and mineralisation of Europe, taking into account other influences such as climate and human activities when our observations seem to point them out.

The description of each element or determinand follows the same scheme. An introductory section, describing the general chemistry and geological occurrence of the element, is followed by the interpretation sections of the different sampling media:

• Soil,
• Humus,
• Stream water,
• Stream sediment, and
• Floodplain sediment.

The final section compares the geochemistry of the different sampling media. In all, these make up seven sections per element.

In the Internet version of the publication, the description texts are found from the Maps table.

The task of writing the general introduction and interpretation text of this vast set of regional geochemical maps of Europe was allocated to different first authors per section, who each coordinated the first draft of their section with a small number of co-authors. These texts were then circulated among geoscientists of all participating national geological surveys for additional contributions to the final text. In the introductory texts below, per section, the principal authors and contributors are named separately, and some general remarks are formulated concerning the interpretation, for the different sample media.

Parts 1 and 2 of the Geochemical Atlas of Europe can be viewed and downloaded from the URL: http://www.gtk.fi/publ/foregsatlas

In Part 1, apart from the geochemical distribution maps, there are useful chapters on the geology, mineralisation, sampling, sample preparation and analysis, database management and map production that should be consulted.

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