Hot Spots MT 2/2023 · 19 Map outlining the spatial distribution of recorded submarine mineral occurrences and potentialities for polymetallic nodules in European territorial waters. (Map: GeoERA Raw Materials) Polymetallic nodules are marine sedimentary mineral deposits, composed predominantly of iron and manganese, that precipitate very slowly from seawater (hydrogenetic) or from bottom sediment pore waters (diagenetic), but most nodules are a combination of both. According to MINDeSEA data, these nodules can be enriched in the following critical elements: cobalt, heavy and light REEs, niobium, scandium, vanadium, lithium and titanium. And there are – at least ocally – anomalous enrichments of high field strength elements such as yttrium, zirconium, tantalum, hafnium, as well as elements that can be oxidized on the surface of manganese oxides such as cerium (a light REE) and tellurium. The majority of them have been delineated in the Baltic Sea or “Baltic Sea Metallogenetic Area” – 184 occurrences, corresponding to 62 % of all occurrences of polymetallic nodules listed for European waters. As said in the MINDeSEA report, relatively high nodule abundances (between 10 and 40 kg/m2) occur in the Gulfs of Riga, Finland and Bothnia in water depths between a few tens of metres and about 250 m, covering areas of a few hundred square kilometres. G. P. Glasby et al., in a research paper published in 1997, entitled “Environments of Formation of Ferromanganese Concretions in the Baltic Sea: A Critical Review,” declare that this abundance is related to the large input of managanese- and iron-rich suspended matter through rivers in the northeast and east (Gulf of Bothnia, Gulf of Finland) and the formation of an oxidized layer in the upper 2 to 15 cm of the sediment column. In addition, fast-growing iron-manganese concretions are mainly found in the western Baltic Sea, their formation being related to the development of summer anoxia and the diagenetic mobilisation of manganese. Other maritime regions in Europe with hightened concentrations of polymetallic nodules are the northwestern continental shelf of the Black Sea (between the Crimean peninsula and the Danube Delta) and the southern part of the Biscay Abyssal Plain (which occupies about half the area of the Bay of Biscay) and the eastern portion of the Iberia Abyssal Plain. Here, ferromanganese concretions are intimately associated with high anomalous concentrations of cobalt and vanadium. Conclusion In September 2020, the European Commission has considered 30 commodities as critical raw materials, three more than in 2017. In this latest list, four more commodities were added, namely bauxite (often containing strategic elements like gallium), titanium, strontium and lithium. As to the latter, several hard rock mining programmes are now coming on stream in Portugal, France, Germany and the Czech Republic. The list also includes some members of the group of REEs, which are in imminent danger due to the fact that the EU is almost 100 % import dependent on six of the 14 light and heavy REEs. Despite new finds of REE in Greenland and the Fennoscandian Shield (Sweden), the EU’s dependence on foreign supplies continues to represent a high risk. It needs to be reduced to a minimum to improve the EU’s resilience towards supply shortages in most of the strategic and critical raw materials. Besides methodologies for rare element recycling, improved access to own (domestic) reserves and resources remains critical to Europe’s economy – and national defence – in the 2020s. For most of the strategic and critical raw materials listed by the European Commission, there is currently no mining production in the EU. This may be due either to the absence of mineral deposits, or more often the limited knowledge of the availability of those materials in certain geological regions, or to economic and societal factors that have a negative effect on exploration or extraction. Since many years, there is increasing interest in marine mineral potentials. However, the seafloor setting is described as immature as an exploration target, and there is currently insufficient data to assess the reserves and resources of metalliferous ores, at least for hydrothermal sulphides (containing ferrous and non-ferrous metals), says the European Commision. The aim of the project “Seabed Mineral Deposits in European Seas: Metallogeny and Geological Potential for Strategic and Critical Raw Materials” (MINDeSEA), which is supported by the EU’s Horizon 2020 research and innovation programme, is to map and characterise the setting, abundance and exploitation potential of submarine mineralisation systems in European territorial and international waters. Part of MINDeSEA, an assessment led by the National Laboratory of Energy and Geology (Laboratório Nacional de Energia e Geologia; LNEG) in Portugal came to the conclusion that seabed mineral deposits – among them polymetallic nodules – are widespread in EU territorial waters. The MINDeSEA final report (October 2021) concludes that many areas do have “potentiality for some strategic and critical raw materials.” f
RkJQdWJsaXNoZXIy MTM5Mjg=