Metallogenic provinces, geochemical provinces and regional geology - what causes large-scale patterns in low density geochemical maps of the C-horizon of podzols in Arctic Europe?

The < 2 mm fraction of 605 samples of the C-horizon of podzols collected fr om an area of 188,000 km(2) in the European Arctic was analysed for more th an 40 chemical elements. The results were used to construct geochemical map s which showed clear regional distribution patterns, notwithstanding the ve ry low sample density of 1 site per 300 km(2). Some of these patterns fit e stablished lithological boundaries. Others fit lineament structures in the area and underline the relative importance of certain tectonic directions s ome of which have not yet been delineated on existing geological maps. Some mark large-scale hydrothermal events and related alteration. Finally, some are connected with prominent, known ore deposits occurring in the area. Ho wever, several large deposits and even famous metallogenic provinces (Fe, N i/Cu) are hardly, or not at all, reflected in the regional geochemical maps . In their present definitions geochemical provinces and metallogenic provi nces are thus not necessarily related. Special geochemical features can occ ur at very different scales. The term geochemical province is so imprecise in terms of processes leading to regional-scale geochemical features that i t should be avoided. Low-density geochemistry can be used to aid the interp retation of the geological evolution of large legions. It can also be used to find prospective areas within such regions. <(c)> 2001 Elsevier Science Ltd. All rights reserved.