General geology, alteration, and iron deposits in the Palaeoproterozoic Misi region, northern Finland

The Paleoproterozoic Misi region forms the northeastern part of the Peräpohja Schist Belt in northern Finland. The area comprises mafic volcanic and sedimentary rocks, differentiated gabbros, and late-orogenic granitoids. Three geochemically different mafic volcanic units were recognised: LREE-depleted amygdaloidal lavas, slightly LREE-enriched lavas, and mafic tuffs that have a flat REE pattern. Sedimentary rocks include arkosites, mica gneisses, dolomitic marbles, quartzites, tuffites, mica schists, calc-silicate rocks and graphite-bearing schists. Two types of gabbros wereidentified: one with a LREE-enriched pattern and another with flat REE pattern. The age of the former is according to Perttunen and Vaasjoki (2001) 2117±4 Ma, whereas there is no age determination for the latter. The granitoid intrusions belong to the ca. 1800 Malate-orogenic group of the Central Lapland Granitoid Complex. The geochemistry and the stable isotope data on mafic lavas and dolomitic marbles show similarities with the mafic volcanic rocks and marbles of the lower part of the Kivalo group in the western part of Peräpohja Schist Belt. Peak metamorphic conditions in the region vary from upper-greenschist to upper-amphibolite facies. Three major stages of deformation were distinguished: N-S compressional D1 with ductile deformation, NE-SW compressional D2 with ductile to brittle-ductile deformation, and E-W compressional D3 with brittle deformation. Several magnetite occurrences are known in the region and four of those have been mined for iron. The ores are mainly composed of magnetite with minor haematite, pyrite, chalcopyrite and bornite. Besides iron, the ores contain small amounts of P, S and V aswell as trace amounts of Cu, Co, Te and Au. The magnetite bodies are hosted by skarnoids within the ca. 2220–2120 Ma dolomitic marble-quartzite sequence, and highly differentiated, intensely albitised, LREE-enriched gabbro. Multistage and -type alteration is characteristic for the entire region. The styles of alteration in the region are: scapolitisation, regional and local albitisation, sericitisation and silicification associated with a major shear zone, and late carbonatisation and carbonate veining associated with brecciation of the ores and their wall rocks. Local intense albitisation and formation of skarnoids and magnetite ores took placeduring the pre-D1 or D1 faulting or shearing which postdate the intrusion of 2120 Ma gabbros. The iron was mobilized from the mafic to intermediate country rocks and/or marble sequence which possibly contained sedimentary iron formation. Regional alteration with the local intense albitisation and ore formation show similar features to the iron oxide-copper-gold type deposits, although the known deposits in the Misi region only contain trace amounts of gold and copper

Climate risk perception, management, and adaptation in the Nordic mining sector

Climate change can affect the mining sector in various ways. Physical impacts can be a threat to mines and personnel, transport infrastructure and supply chains, while the low-carbon transition may entail transition risks stemming from e.g., the need to respond to mitigation and adaptation policies, as well as opportunities in the form of increased metal and mineral demand. However, there is little knowledge of how mining companies perceive, manage, and respond to risks related to climate change. To address this knowledge gap, we examined annual and sustainability reports from 2019 for active metal mines in Finland, Sweden, and Norway. Through a structuring qualitative content analysis, we analysed the mining companies’ self-reported experience of and expectations for climate change impacts and risks, as well as adaptation and management activities taken or planned. Our findings indicate that physical impacts of climate change are not perceived as a major risk. In contrast, mitigation activities and reactions to climate policies play an important role, at least for some of the companies. Hence, the mining sector would benefit from more stringent risk reporting regulations and distinctive guidelines, as well as more research on the direct and indirect climate change impacts.Peer reviewe

Potential benefits and constraints of development of critical raw materials' production in the EU: analysis of selected case studies

ABSTRACT: Major benefits and constraints related to mineral extraction within the EU have been identified on the examples of selected critical raw materials’ deposits. Analyzed case studies include the following ore deposits: Myszków Mo-W-Cu (Poland), Juomasuo Au-Co (Finland), S. Pedro das Águias W-Sn (Portugal), Penouta Nb-Ta-Sn (Spain), Norra Kärr REEs (Sweden) and Trælen graphite (Norway). They represent different stages of development, from the early/grassroot exploration stage, through advanced exploration and active mining, up to reopening of abandoned mines, and refer to different problems and constraints related to the possibility of exploitation commencement. The multi-criteria analysis of the cases has included geological and economic factors as well as environmental, land use, social acceptance and infrastructure factors. These factors, in terms of cost and benefit analysis, have been considered at three levels: local, country and EU levels. The analyzed cases indicated the major obstacles that occur in different stages of deposit development and need to be overcome in order to enable a new deposit exploitation commencement. These are environmental (Juomasuo and Myszków), spatial (Juomasuo) as well as social constraints (Norra Kärr, Juomasuo). In the analyzed cases, the most important constraints related to future deposit extraction occur primarily at a local level, while some important benefits are identified mainly at the country and the EU levels. These major benefits are related to securing long-term supplies for the national industries and strategically important EU industry sectors.info:eu-repo/semantics/publishedVersio

GeoERA Raw Materials Monograph : the past and the future

ABSTRACT: GeoERA Minerals projects have produced data aimed at supporting Europe’s minerals sector and to assist the European Commission to realise its goals for raw materials. Data has been compiled on mineral occurrences and mineral provinces across Europe, in particular, areas with potential to host Critical Raw Materials. Anecdotal evidence from the minerals sector provides an indication of the likelihood of exploration leading to mine development. For every 1,000 mineral showings examined, only 100 may receive further exploration work and of those 100, only 10 may warrant more detailed sampling either through trenching, drilling or other means and of those 10 only 1 may proceed to an evaluation through a full feasibility study which itself has only 50% chance of being positive. Following this, any project for which a mine proposal is made must undergo a full evaluation and permitting by authorities including full public consultation. The proposal may or may not pass this scrutiny. In terms of a schedule, the generally accepted minimum time frame from discovery to production is 10 years and usually much more, up to 20 years.info:eu-repo/semantics/publishedVersio

Epigenetic au and cu-au deposits

Godkänd; 2007; 20080104 (bajo

Epigenetic au and cu-au deposits

Godkänd; 2007; 20080104 (bajo

The Mustajarvi orogenic gold occurrence, Central Lapland Greenstone Belt, Finland : a telluride-dominant mineral system

The Mustajarvi gold occurrence lies in the southern part of the Paleoproterozoic Central Lapland Greenstone Belt, in proximity to the first-order transcrustal Venejoki thrust fault system. The gold occurrence is structurally controlled by the second-order Mustajarvi shear zone, which is located at the contact between siliciclastic metasedimentary and mafic to ultramafic metavolcanic rocks. The main mineralization comprises a set of parallel veins and sulfidized rocks that are slightly oblique to the shear zone and are hosted by third-order structures likely representing Riedel R-type shears. The gold-mineralized rock at Mustajarvi is associated with pyrite that is present in 0.15- to 1-m-wide quartz-pyrite-tourmaline veins and in zones of massive pyrite in the host rocks with thicknesses ranging from 1.15 to 2 m. In unweathered rock, hypogene gold is hosted by Au- and Au-Bi-telluride micro-inclusions in pyrite, whereas strong weathering at near surface levels has caused a remobilization of gold, resulting in free gold deposited mainly in the cracks of oxidized pyrite. The geochemistry of both mineralization styles is typical of orogenic gold systems with strong enrichments comprising Au, B, Bi, CO2, Te, and Se; and less consistent anomalous amounts of Ag, As, Sb, and W. Unusual for orogenic gold deposits is the strong enrichment of Ni and Co, which leads to the classification of Mustajarvi as orogenic gold occurrence with atypical metal association.Peer reviewe

Ore deposits

Godkänd; 2007; 20080104 (bajo

Geological and tectonic evolution of the northernpart of the Fennoscandian Shield

Godkänd; 2007; 20080103 (bajo

Metallic mineral deposits in the Nordic countries

The Nordic countries, including Greenland, have a long tradition in mining. Documented mining dates back to the 8th century AD. Today this region is the most important metallic mining district of the European Union. Metals are producedfrom active mines in all countries except Iceland and related industries are thriving in all countries. Important ore deposit types include: volcanogenic massive sulphide deposits (Cu, Zn, Pb, Au, Ag), orogenic gold deposits (Au), layered intrusions (Ni, PGE, Ti±V), intrusive hosted Cu-Au, apatite-Fe deposits, Cr and anorthosite hosted Ti deposits. Besides these welldocumented deposits, new kinds of deposits are being explored, e.g., iron oxide-copper-gold (IOCG), and shalehosted Ni-Zn-Cu and different types of uranium deposits.Validerad; 2008; 20080821 (pawe)</p