GEMAS: Precious metal spatial distribution patterns in European soil

Precious metal (Ag, Au, Pd, Pt) concentrations are reported for the [ view full abstract ]

Precious metal (Ag, Au, Pd, Pt) concentrations are reported for the <2 mm fraction of soil samples from agricultural (Ap horizon, 0–20 cm; N=2218) and grazing land (Gr, 0–10 cm; N=2127). The survey covers 33 European countries and 5.6 million km2 at a sample density of 1 site/2500 km2. Element concentrations were analysed in two different extractions, aqua regia and mobile metal ion (MMI®) with inductively coupled plasma emission mass spectrometer-finish.
Geochemical maps of Ag and Au for both land use types (Ap and Gr) in aqua regia extraction show overall similar spatial distribution patterns; the dominant feature is the southern limit of the last glaciation, indicated by a sharp break between northern and southern European Ag and Au concentrations. This break, although more subtle, is still discernible on the MMI® extraction Au and Ag maps. Most of the Ag and Au anomalies are geogenic (e.g., associated with known mineralised districts), but there are some interesting anomalous patterns that indicate an anthropogenic footprint (e.g., London, Paris, Madrid).
Although most of the Pd and Pt aqua regia results are below detection, there are a number of interesting continental-, regional- and local-scale patterns. Some of the Pd and Pt aqua regia anomalies are associated with mafic and ultramafic rocks (e.g., Norway, Hellas), but this is not always the case, some are related to karst and bauxite/laterite mineralisation (e.g., Croatia, Bosnia and Herzegovina, Hellas), and to ashes of historical volcanic eruptions of Vesuvius, Campi Flegrei and Mount Vulture (e.g., Italy).