9. Economic geology

9.1. Circular economy

9.2. Mineral resources and deep-sea mining in international and national seabed areas

9.3. Open Session: Economic Geology

9.1. Circular economy

                       ORAL PRESENTATIONS                    

Turning anthropogenic stocks into economic viable ‘ore’ reserves – major challenges for the Circular Economy

Per Kalvig¹, Rune J. Clausen², Tonny B. Thomsen³ and Jonas Nedenskov^4
1Center for Minerals and Materials (MiMa), GEUS, ²Cent for Minerals and Materials (MiMa), GEUS, ³Dep. Economic Geology, GEUS, ⁴Amager Resource Centre (ARC)
Classical mineral exploration and resource assessment techniques are inadequate tools for assessment of the financial viability of anthropogenic end-of-life stocks. In order to develop ample mining technologies and beneficiation flow-sheets that provides for a viable exploitation of secondary raw materials there is a fundamental need for characterizing the composition and properties of secondary raw materials.

Example; the Danish WtE plants produce c. 600.000 tpa of bottom ashes that potentially constitute important secondary multi-element resources, which is generally considered as waste by plant-owners, and left to be utilized by entrepreneurs. The entrepreneurs apply a scrap-metal approach to extract some of the metals, and the remains are used e.g. in road construction. In order to reduce leakages, some challenges need to be targeted and overcome:

Challenge 1: Physical and chemical characterization of the heterogenic resource. Metals mainly occur as primary alloys and sedondary alloys developed in the incineration.

Challenge 2: Representative sampling of the heterogenic flow of the ‘ore’ material, coping with a wide range of particle sizes and shapes of the ‘ore minerals’.

Challenge 3: Estimation of the grades and in-situ ‘ore’-value, are critical for developing a ‘mining’ set-up and beneficiation flow charts.

Challenge 4: Estimation of the dynamic reserve tonnage.

Challenge 5: Estimation of project viability: the in-situ ‘ore’-value/’ore-concentrate’. Absence of parameters characterizing the ‘ore’ and the ‘mineral concentrate’, as well as non-transparent price schemes, prevents the development of feasibility studies.

In conclusion; inadequate resource assessments are major obstacles for addressing and closing leakages in the circular economy.

Characterization of Raw Materials and Recycled Stone Wool Waste for Production of Stone Wool Melt

Vickie Schultz-Falk¹, Peter Arendt Jensen², Karsten Agersted³ and Mette Solvang^1
1ROCKWOOL International A/S, ²Department of Chemical and Biochemical Engineering, Technical University of Denmark, ³Department of Energy Conversion and Storage, Technical University of Denmark
Stone wool waste is generated either during production, where edges are cut off in the shaping process, or during renovation or demolition of buildings. Stone wool is produced by forming a melt that is spun into fibers. The raw materials include mineral raw materials as well as secondary raw materials i.e. waste from other industries. It is also possible to re-melt stone wool waste and thus recycle the waste material back into the production process.

This study investigates the differences in heat response of a conventional stone wool raw material mix and of stone wool waste. The study combined Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD) and Hot Stage Microscopy (HSM). The materials are compared in terms of thermally induced processes occurring in the materials, melting temperature, crystallinity and energy consumption associated with heating and melting of the materials.

DSC reveals that the raw material mix and stone wool waste have fundamentally different heat responses: the raw material mix decarbonizes and the wool crystalizes before both melting. XRD is used to investigate the crystallinity of the mineral raw materials and the crystals formed in the stone wool waste upon heating. HSM reveals that stone wool waste initiates melting at lower temperatures than the conventional raw material mix.

Understanding the differences between the conventional raw material mix and the recycled stone wool waste will ultimately help to optimize the production process towards recycling larger amounts of stone wool waste.

                       POSTER PRESENTATIONS                    

Utilization of biochar as a cover material in mine waste areas

Pertti Sarala¹ and Raija Pietilä^2
1Geological Survey of Finland, P.O. Box 77, 96101 Rovaniemi, Finland/Oulu Mining School, Univ. Oulu, ²Geological Survey of Finland, P.O. Box 77, 96101 Rovaniemi, Finland
Good mineral waste coverages and landscaping solutions in northern mining industry will be developed and tested in the project ‘Utilization of biochar in dry cover material and landscaping of mine waste areas’ (Biopeitto) funded by the European Regional Development Fund. From the perspective of sustainable development and regional well-being, the solutions that will minimize the costs for environment and increase the local livelihoods should be developed in the northern region itself. Testing biochar, mine wastes and other rest materials as the component of mineral waste cover in tailings and waste rock pile solutions are environmentally important. The tests aim at finding the best ways to improve cover material’s long-term durability and stability, prevent erosion, and improve the sustainability of water management, carbon balance and nutrient economy. Benefit of the use of biochar is its’ local production which diminishes the transport and storage costs and opens new possibilities to develop local entrepreneurship. Tailings are produced in large quantities by the mining industry and it might be more economical and beneficial to use the waste as a resource than treat it as a waste. Available materials needed to improve tailings properties such as wood, fibre and bio sludge but also other rest materials from other industries should be tested to enhance their valorisation. The project is led by the Geological Survey of Finland and other research partners are the Natural Research Institute Finland and the Oulu Mining School of the University of Oulu.

9.2. Mineral resources and deep-sea mining in international and national seabed areas

                       ORAL PRESENTATIONS                    

Deep-sea mineral resources within National Jurisdiction

Harald Brekke¹, Georgy Cherkashov² and Pedro Madureira^3
1Norewegian Petroleum Directorate, ²VNIIOkeangeologia, University of St. Petersburg, ³EMEPC
According to the UN Convention on the Law of the Sea, the continental shelf is the area of seabed that is under the jurisdiction of the coastal states, which in some cases may extend beyond 200 nautical miles. According to the Convention, the exploitation of any continental shelf resources beyond 200 nautical miles is subject to a royalty to be paid through the International Seabed Authority. In most parts of the world, the continental shelf consists of an inner, shallow part and an outer, deep-sea part. Oil and gas, placers and aggregates are associated with the shallow parts of the continental shelf, while polymetallic mineral resources are found in the deep-sea parts and likely to be relevant for royalty payments. In wide platform areas, like those of the Atlantic, oil and gas may also be subject to such payments. The polymetallic minerals are regarded as potential sources of nickel, copper, cobalt, manganese, zinc, lead, gold, cobalt, tellurium, and possibly REEs. Estimates of the mineral resources of the deep sea and their partition between the continental shelf and the international seabed are still very uncertain. Recently published studies indicate that, depending on the type of mineral, between 20% to 50% of the resource may be located within the continental shelf areas. Recent test mining by Japan and the development of the Solwara 1 Mine in Papua New Guinea indicate that sulphides will be the first deep sea mineral to be exploited, and that it will happen within the continental shelf.

Exploration of seafloor massive sulfides: current status and perspectives.

Georgy Cherkashov^1
1VNIIOkeangeologia, St Petersburg, Russia
Seafloor massive sulfide (SMS) deposits present the third type of a short list of deep-sea minerals after ferromanganese nodules and cobalt rich ferromanganese crusts. The discovery of hydrothermal vents and associated massive sulfides in the end of 1970s had not only fundamental but also economic importance due to extraordinary concentrations of metals being discharged from hot vents to the sea bottom. The major components of SMS are Cu, Zn, Pb, Au and Ag. The high grades of such minor high/green-tech components as Se, Te, Ge, Bi, As, Cd, Ga, Tl and In are also detected in SMS deposits.

Most of SMS deposits are localised in the area beyond the national jurisdiction which administrating by International Seabed Authority (ISA). Currently 6 contracts for exploration of SMS deposits are signed between States Parties and ISA for the areas in the Atlantic and Indian oceans. Different geological and geophysical methods are used for the prospecting of active and inactive SMS deposits. The first exploration contract should be completed in 2026.

SMS deposits localized within EEZ are the subject for exploration study as well. Most of these deposits which distribute along the island arc systems in the Pacific are well explored and even ready to be mined (e.g. Okinawa Trough, Bismark Sea). The technologies for future mining are in process of being designed and methods of metals extraction from SMS already exist being similar to that of land-based volcanogenic massive sulfide deposits.

Sulfide mineralogy of the Loki’s Castle hydrothermal vent, Arctic Mid-Ocean Ridge

Kristian Drivenes¹, Ben Snook¹ and Kurt Aasly^1
1Norwegian University of Science and Technology
Samples from the active Loki’s Castle hydrothermal vent were collected from the seafloor by ROV during the MarMine cruise in 2016. The hydrothermal vent sites consist of black smoker systems, and as such have diverse mineralogy with highly heterogeneous macro and micro textures. The samples currently under investigation represent chimney collapse breccia rather than massive sulphide from the core of the deposit. Sulfide mineralization in the white smoker material is limited with minor sphalerite, galena and pyrite. The less common black smoker material is dominated by silica and sulfate gangue, with sulfides occurring as lenses and patches of fine-grained material and, locally, larger grains.

In the sulfide-rich areas, the sulfides occur in mineralogically and metallogenically distinct zones on the cm scale. The Fe-rich zones comprises intergrown pyrite and marcasite, the Zn-rich zones comprises sphalerite, and the Cu-rich zones comprises an isotropic Cu-Fe-S phase, likely isocubanite, with both sharp submicron lamellae and larger exsolutions of chalcopyrite. Minor pyrrhotite and galena was observed. There is significant overlap between the zones, especially the Zn-rich and Cu-rich zones, where the isocubanite replaces sphalerite. The sphalerite is infected with chalcopyrite disease, but under the optical microscope several grains and zones appear to be inclusion-free. However, SEM investigations show lamellae in sphalerite less than 100 nm wide, oriented in the same crystallographic planes as chalcopyrite lamellae in neighboring isocubanite, indicating that not all lamellae in sphalerite may be visible in the optical microscope.

Uncertainties in grade, tonnage, and distribution estimates for seafloor massive sulfide deposits

John W Jamieson¹ and Rolf B Pedersen^2
1Memorial University of Newfoundland, Department of Earth Sciences, ²K.G. Jebsen Centre for Deep Sea Research, University of Bergen
The economic potential of deep sea mining is ultimately dependent on the size, grade, and distribution of ore deposits on the seafloor. For seafloor massive sulfide (SMS) deposits, there have been several studies that have reported quantitative estimates of the resource potential at both global and regional scales (including the North Atlantic), and these resource estimates are being utilized to drive policy decisions related to the economic potential of SMS mining, and associated exploitation and environmental regulations. However, the geological uncertainty associated with these resource estimates is significant. Development and regulatory decisions must ultimately be tied to not only the grade and tonnage estimates of individual deposits, but also an understanding of the associated uncertainty of these estimates. In this presentation, we will discuss the current state of knowledge of the size, grade and distribution of SMS deposits. We will focus on how these estimates are determined, the evolving uncertainties related to these estimates, and strategies that should be implemented to reduce these uncertainties, including approaches to exploration, sampling and drilling.

Deep sea mineral resources in the international seabed area

Pedro Madureira¹, Harald Brekke² and Georgy Cherkashov^3
1EMEPC, ²Norwegian Pteroleum Directorate, ³VNIIOkeangeologia, University of St. Petersburg
According to the UN Convention on the Law of the Sea, the seabed and subsoil areas of the world oceans are divided into two parts: the international seabed under the jurisdiction of the International Seabed Authority (ISA), and the continental shelf under the jurisdiction of the coastal states. The resources of the international seabed area (termed “the Area”), are managed by the ISA on behalf of the mankind. Today, there is an increasing interest for the mineral resources of the deep ocean because of the demand for certain metals needed in green technology. The most promising mineral resources in the Area for supplying global needs are polymetallic nodules, polymetallic sulphides and ferromanganese crusts. They are regarded as potential sources of nickel, copper, cobalt and manganese (nodules), of copper, zinc, lead and gold (sulphides), and of cobalt, tellurium, manganese and possibly REEs (crusts). Currently, the ISA have 28 Contractors carrying out exploration activities in the Area, rising from eight before 2011. Estimates of the mineral resources of the deep sea are still very uncertain. However, exploration and scientific studies in recent years indicate that the Co and Ni resources of the deep sea exceeds those onshore by ten and four times, respectively. In the case of Mn and Mo, the resources of the deep ocean match those onshore. No one has so far started any commercial exploitation of these resources. The ISA is currently developing its regulations for exploitation, starting with the nodules. These regulations should be completed by 2020.

The Seven Sisters Hydrothermal System on the Arctic Mid-Ocean Ridge

AFA Marques¹, RB Pedersen¹, DL Roerdink¹, T Baumberger², CEJ de Ronde³, RG Ditchburn³, IH Thorseth¹, I Okland¹, MD Lilley⁴, M Whitehouse⁵ and A Denny^1
1K.G. Jebsen Centre for Deep Sea Research University of Bergen, Norway, ²Pacific Marine Environmental Laboratory (PMEL), National Oceanic and Atmospheric Administration (NOA, ³GNS Science New Zealand, ⁴School of Oceanography, University of Washington US, ⁵Swedish Museum of Natural History, Stockholm Sweden
We present new findings on the shallow, hybrid, seafloor hydrothermal system (known as the Seven Sisters site) with epithermal-style mineralization that is hosted by mafic volcaniclasts on the slow spreading Northern Kolbeinsey ridge on the Arctic mid-ocean ridge. The system lies on top of a flat-topped volcano at ~130 m depth from which relatively high temperature (up to 200°C) phase-separating fluids vent from smoking craters and unique pinnacle-like edifices on top of mounds. The hydrothermal mineralization at Seven Sisters manifests as replacement of mafic volcaniclasts, direct precipitation from the hydrothermal fluid, and as vapor elemental sulfur sublimates. Barite is ubiquitous and is replaced by pyrite, which is the first sulfide to form, followed by Zn-Cu-Pb-Ag bearing sulfides, sulfosalts and silica. The mineralized rocks at Seven Sisters contain appreciable amounts of ‘epithermal suite’ elements with secondary alteration minerals. Vent fluids have a pH of ~5 and are Ba and metal-depleted. Sulfide and secondary alteration mineralogy, fluid and gas chemistry, as well as d34S and 87Sr/86Sr isotope values indicate that mineralization at Seven Sisters is sustained by the input of magmatic derived fluids with seawater contribution. Radiometric dating of barite suggests that this hydrothermal system has been active for at least 4670 ± 60 years.

Preliminary characterisation of potential seafloor massive sulphide ore from the Loki’s Castle deposit, on the Arctic Mid-Ocean Ridge.

Ben Snook¹, Kristian Drivenes¹, Kurt Aasly¹ and Gavyn Rollinson^2
1NTNU, ²University of Exeter
Ensuring efficient ore characterisation is necessary for all stages of mine planning, thereby streamlining deposit identification, resource extraction, mineral processing and waste management. It provides information for compositional, chemical, textural and mineral liberation considerations, and tracks the effectiveness of mineral processing. As such, defining the most effective assessment techniques for new ore types is of high importance.

In response to growing demand [1], potential new sources of copper and zinc have been identified in the deep sea, from seafloor massive sulphides (SMS) [2,3]. One site under Norwegian jurisdiction demonstrating good possibilities for SMS mineralisation is Loki’s Castle, where active hydrothermal venting occurs at 2400 m depth on the slow spreading Arctic Mid-Ocean Ridge [4]. The site consists of two mounds, each approximately 150 m across and 30 m high, capped by 5 active chimneys releasing 320° C fluids [4]. During the 2016 MarMine cruise [5] boulders were collected from the mounds’ flanks, which represent collapsed chimney fragments that have formed debris flows. The vent sites appear to consist of both white and black smoker systems, and as such have a diverse mineralogy with highly heterogeneous macro and micro textures.

We report initial approaches to determining analytical techniques to characterise SMS ore; petrography, geochemistry, and automated mineralogy. Preliminary results indicate that typical sulphide mineral assemblages in samples with elevated Cu and Zn grades comprise fine grained chalcopyrite, isocubanite, sphalerite and pyrite, often with complex textures: chalcopyrite overgrowths on isocubanite; sub-micron laminations of chalcopyrite within isocubanite; micron scale chalcopyrite blebs within sphalerite.

References
[1] Singer D.A. 2017: Future copper resources. Ore Geology Reviews, 86, 271-279.

[2] Hannington M., Jamieson J., Monecke T., Petersen S., Beaulieu, S. 2001: The abundance of seafloor massive sulphide deposits. Geology, 39, 1155-1158.

[3] White M., Manocchio A., Sant T., Johnston M., Lowe J. 2011: Resource drilling of the Solwara 1 seafloor massive sulphide (SMS) deposit. Offshore Technology Conference, Houston, Texas.

[4] Pedersen R.B., Rapp H.T., Thorseth I.H., Lilley M.D., Barriga F.J.A.S., Baumberger T., Flesland K., Fonseca R., Fruh-Green G.L., Jorgensen S.L. 2010: Discovery of a black smoker vent field and vent fauna at the Arctic Mid-Ocean Ridge. Nature Communications, 1:126.

[5] Ludvigsen M., Aasly K., Ellefemo S., Hilario A., Ramirez-Llodra E., Søreide F., Falcon-Suarez I., Juliani C., Kieswetter A., Lim A., Malmquist C., Nornes S.M., Paulsen E., Reimers H., Sture Ø. 2016: NTNU Cruise reports 2016 no 1 MarMine Arctic Mid ocean Ridge 15.08.16-05.09.16, Trondheim, Norway, ISSN 2535-2520.

CHARACTERISEING MINERAL REPLACEMENTS REACTIONS IN CU-FE-ZN-S MINERALS FROM THE ARCTIC MID-OCEAN RIDGE USING SEM, EBSD AND OPTICAL MICROSCOPY

Bjørn Eske Sørensen¹, Kristian Drivenes¹ and Gert Nolze^2
1NTNU, Department of Geoscience and Petroleum, ²Bundesanstalt für Materialforschung , Berlin. Department of Materials Engineering
Ore minerals in samples collected from black smokers at Loki’s Castle at the Arctic Mid-Ocean ridge show complex intergrowth and exsolution textures. Cu-Fe-S mineral(s) appear in sphalerite as several µm size rounded inclusions, or as fine lamellae parallel to {001}. Sphalerite (sph) (Zn,Fe)S is replaced by a Cu-Fe-S phase (isocubanite), which itself has exsolutions of mostly submicron lamellae (chalcopyrite?). The matrix phase is isotropic, appears pinkish yellow, and has a composition close to cubanite (CuFe2S3). The lamellae are less pinkish, and have compositions close to chalcopyrite (CuFeS2, tetragonal). In addition, a second set of exsolutions appears as wavy laths. Understanding the relations between the mineralizing phases are imperative to understand the genesis of the deposits and hence also to make realistic models of the economic potential.

Further work will reveal more details on the relationship between the phases. After polishing with Ar-ions the pattern of isocubanite and sphalerite were indexable, however because sphalerite and isocubanite have very similar structures they could only be differentiated using the combination of optical and backscattered electron imaging, EDS (energy-dispersive spectroscopy) and EBSD. However, the EBSD reveals topotaxial relations between sphalerite and isocubanite that preserves the orientation of the host, reinforces the interpretation that isocubanite replaces sphalerite rather than growing together with sphalerite. Different methods of indexing the patterns and improved collection may enable us to distinguish also the chalcopyrite lamellae from the host isocubanite and sphalerite though the chalcopyrite structure is very similar to the host phases.

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9.3. Open Session: Economic Geology

                       ORAL PRESENTATIONS                    

Paragenetic evolution of hydrothermal REE mineralisation in the Olserum-Djupedal area, SE Sweden

Stefan S. Andersson¹, Thomas Wagner², Erik Jonsson³ and Radoslaw M. Michallik^1
1Department of Geosciences and Geography, University of Helsinki, ²Institute of Applied Mineralogy and Economic Geology, RWTH Aachen University, ³Geological Survey of Sweden, Department of Mineral Resources
The REE mineralisation in the Olserum-Djupedal area is located at the border of the Palaeoproterozoic Västervik sedimentary formation and c. 1.8 Ga granitoids belonging to the Transscandinavian Igneous Belt (TIB) in SE Sweden. The mineralisation is dominated by the phosphates monazite-(Ce), xenotime-(Y) and variably REE-bearing fluorapatite. These mostly formed, along with subordinate (Y,REE,U,Fe)-(Nb,Ta) oxides, during an initial hydrothermal stage. During a subsequent stage, allanite-(Ce) formed locally, and secondary monazite-(Ce) and xenotime-(Y) also formed, mainly by leaching and remobilisation of REE from fluorapatite. Similar coupled dissolution-reprecipitation processes subsequently also affected primary monazite-(Ce), xenotime-(Y), and minor (Y,REE,U,Fe)-(Nb,Ta) oxide phase(s). This mobilised REE, Th, U and Nb-Ta, and caused the formation of additional xenotime-(Y), monazite-(Ce), fluorapatite and variable amounts of allanite-(Ce) – ferriallanite-(Ce), uraninite, thorite and columbite-(Fe) (Andersson et al., 2018). Bastnäsite-(Ce) and subordinate synchysite-(Ce) characterise the youngest REE mineralisation stage, and formed from the low-temperature alteration of allanite-(Ce) and ferriallanite-(Ce). We interpret the paragenetic sequence to essentially be the result of decreasing temperatures, from an initial high-temperature hydrothermal stage (≥600°C) to a low-temperature stage (<<400°C). In addition, local differences in fluid chemistry, particularly the Ca content, as well as fluid oxidation state, facilitated the dissolution-reprecipitation processes, and ultimately governed the stability of the REE minerals in the ore assemblages of the Olserum-Djupedal area.

References
Andersson, S.S., Wagner, T., Jonsson, E., & Michallik, R.M. (2018) Mineralogy, paragenesis and mineral chemistry of REE minerals in the Olserum-Djupedal REE-phosphate mineralization, SE Sweden. American Mineralogist, in press, http://dx.doi.org/10.2138/am-2018-6202

Critical metal mineralisation in Sweden: overview and highlights

Erik Jonsson¹, Karin Högdahl², Martiya Sadeghi¹ and Nikolaos Arvanitidis^1
1Geological Survey of Sweden (SGU), Department of Mineral Resources, Box 670, SE-75128 Uppsala, Swed, ²Department of Earth Sciences, Mineralogy, Petrology and Tectonics, Uppsala University, Villavägen 1
Critical metals, as part of what is presently defined by the EU (https://ec.europa.eu/growth/sectors/ raw-materials/specific-interest/critical_en) as Critical Raw Materials (CRM), are increasingly sought for from both primary and secondary sources. The Swedish part of the Fennoscandian Shield, with its major ore provinces Bergslagen, Skellefte district and Norrbotten, contains a significant number of primary sources, mineralisations with variably well-known potential for critical metal production. Traditional by-product critical metals such as antimony , cobalt and indium are variably known, the latter confined to some skarn-associated sulphide-oxide mineralisations in westernmost Bergslagen, while the former mainly occurs hosted by accessory sulphosalts in polymetallic sulphide deposits in several regions, chiefly in Bergslagen and the Skellefte district. , Cobalt is represented by several different deposit types including e.g. skarns and volcanosedimentary-associated massive sulphides. While tungsten is known from a number of deposits, these are typified but not limited to skarn-hosted scheelite, which account for the most important and recently mined deposits, located in northwestern Bergslagen. Elevated gallium and germanium contents are associated with rare earth elements (REE)-rich iron oxide skarn deposits in Bergslagen, and the potential for REE is relatively good, in these and other types of mineralisations, as recently noted by Goodenough et al. (2016), in several areas from southern Sweden (Norra Kärr and Olserum), via Bergslagen, to, a.o., the Kiruna type apatite-iron oxide ores of Norrbotten. The REEs in Sweden will be outlined in more detail in an upcoming SGU report, based on work done within the EURARE project (www.eurare.eu).

References
Goodenough, K. M., Schilling, J., Jonsson, E., Kalvig, P., Charles, N., Tuduri, J., Deady, E. A., Sadeghi, M., Schiellerup, H., Müller, A., Bertrand, G., Arvanitidis, N., Eliopolous, D. G., Shaw, R. A., Thrane, K. & Keulen, N. 2016: Europe´s rare earth element resource potential: an overview of metallogenetic provinces and their geodynamic setting. Ore Geology Reviews 72, 838-856.

Towards Real-Time Ore Grade Evaluation using Laser-Induced Breakdown Spectroscopy

Lasse Kangas¹, Roel van Toorenenburg¹ and Jussi Leveinen^1
1Department of Civil Engineering, Aalto University, Espoo, Finland
On mining operations, Grade-control is based on laboratory measurements from blast-hole samples or appropriate type of well logging (e.g. gamma logging) to characterize each block. The problems with these techniques are that they slow, costly and the results are not immediately available. To overcome these issues, it is essential to develop new sensor technologies that can provide elemental and mineralogical information real-time and on-site.

Here, a case study using Laser-Induced Breakdown Spectroscopy (LIBS) and samples of Parainen limestone quarry is presented. The aim of the research was to resolve, if LIBS measurements can be used to characterize the ore body during the blast-hole drilling. The quality parameters that are used in Parainen for the ore grade evaluation are Ca/Si+Al and the magnesium content of the samples. The samples consisted of drill cuttings samples from three different blast-holes and four bulk samples of different ore grades collected from the stockpiles. The bulk samples were crushed, sieved and resorted to get the same grain size distribution with the drill cuttings. The cuttings and the crushed bulk samples were measured by free falling them via funnel to mimic the moving particles in the drill tube.

The results from the LIBS measurements were validated using synchrotron X-ray diffraction and gamma logging from the blast-holes. Our preliminary results suggest that LIBS can be used as an on-line analyzing technique during the drilling process. The ore type and an approximation of the ore grade can be detected from the spectral data.

Non-invasive and non-destructive quantification of wollastonite in limestones using Raman spectroscopy

Kati Laakso¹, Lasse Kangas¹, Saara Kaski², Heikki Häkkänen³ and Jussi Leveinen^1
1Department of Civil Engineering, Aalto University, Espoo, Finland, ²Department of Chemistry, University of Jyväskylä, Jyväskylä, Finland, ³Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
Wollastonite is an economically important mineral that is used to manufacture plastics, ceramics and other products. Finland is currently among the top producers of wollastonite in the world, and the largest in Europe. Finnish wollastonite is sourced from the Ihalainen deposit in Lappeenranta, southeastern Finland. Here, wollastonite is extracted from Paleoproterozoic (1.9 Ga) limestones that also host industrial-grade calcite. Processing of these rocks requires certain mineralogical compositions (e.g.: 21% of wollastonite) that determine the processing quality of the rock. Currently, labor-intensive laboratory analytical technology is commonly used for the mineralogical characterization of rocks. Laser-spectral methods have the potential to partially replace such technologies, and for this end, Raman offers a fast, non-invasive and non-destructive alternative.

To test the ability of the Raman technology to classify wollastonite-bearing limestone rocks into different quality categories, three samples were acquired from the Ihalainen deposit and these samples were scanned using a Raman setup. Different data analysis methods were then applied to map the spatial distribution and relative abundances of the minerals. The results were validated using the scanning electron microscopy (SEM) system of the Geological Survey of Finland.

The preliminary results suggest that the relative quantity and the spatial distribution of wollastonite can be mapped using high spatial resolution Raman data. The ongoing study will next focus on acquiring more samples from the study area, and using these samples, to further test the potential of Raman for the detection of the processing quality of rocks.

Zn-Pb-Cu sulfide-bearing glacial sandstone erratics near Raahe on the western coast of Finland as indicators of Paleozoic base metal mineralization at the bottom of the Bothnian Bay

Erik Nilsson¹, Eero Hanski², Hannu Huhma³, Yann Lahaye³, Timo Mäki⁴, Hugh O’Brien³ and Kari Strand^2
1Geosciences and Environmental Engineering, Luleå University of Technology, Sweden, ²Oulu Mining School, University of Oulu, Finland, ³Geological Survey of Finland, Espoo, Finland, ⁴First Quantum Minerals Ltd., Pyhäsalmi, Finland
Over the past tens of years, sandstone erratics variably enriched in Zn, Pb and Cu have been collected from the coast south of Raahe, but their source has remained unclear. In these non-metamorphosed and non-deformed erratics, detrital grains of quartz and minor feldspar are cemented by calcium carbonate, which is partly or wholly replaced by ore minerals, including sphalerite, galena, pyrite, marcasite, and chalcopyrite. Analyzed boulders have yielded total base metals contents between 1 and 10 wt%. The FeS content in sphalerite is low and variable, ranging commonly between 0.5-15 mol-%, which is in harmony with its coexistence with pyrite.

Galena shows very radiogenic Pb isotope compositions, with ²⁰⁶Pb/²⁰⁴Pb falling in the range of 20.55−21.06 and ²⁰⁷Pb/²⁰⁴Pb between 15.90 and 15.94. These compositions are similar to those measured for the Laisvall Pb-Zn MVT deposit in the Swedish Caledonides, being consistent with a similar Ordovician age of ore formation. However, S isotope analyses of pyrite yielded mostly negative δ³⁴S values from −15.6 to −7.6, which are distinctly different from the generally heavy sulfur isotope compositions (ave. +24) reported from the Laisvall-type deposits. These results together with some mineralogical differences (presence of chalcopyrite, absence of fluorite and barite) suggest that the boulders were not derived from the eastern front of the Caledonian orogen but their source occurs much closer, likely being a so-far-undiscovered base metal deposit under the Bothnia Bay.

Cu-Mo mineralization epochs in NW Iran and their temporal relationship with metallogenic zones of neighboring Lesser Caucasus and Central Iran

Vartan Simmonds^1
1Research Institute for Fundamental Sciences, University of Tabriz, Tabriz, Iran
The Tertiary Urumieh–Dokhtar magmatic arc (UDMA) in Iran represents the northeast-ward subduction of the Neo-Tethyan oceanic crust beneath the central Iranian domain during the late Mesozoic-early Cenozoic. It coincides with the porphyry copper metallogenic belt, including 3 metallogenic zones in NW (Ahar-Jolfa), central and SE parts, which host many porphyry copper deposits (PCDs) and prospects. The Ahar-Jolfa metallogenic zone includes the Qaradagh and Sheyvardagh batholiths and many smaller intrusions and includes porphyry, skarn and vein-type mineralizations. This zone shares many magmatic, geodynamic and mineralization features with the neighboring South Armenian Block (SAB), where the Meghri-Ordubad composite pluton of Eocene-Miocene age hosts many porphyry Cu-Mo deposits. By comparing the measured Re-Os and U-Pb ages of mineralizations in NW Iran [1,2,3,4,5], it can be concluded that porphyry mineralizations have occurred in three epochs of late Eocene (~35 Ma), middle Oligocene (31-25 Ma) and early Miocene (22-20 Ma). Mineralizations here coincide with the third epoch of such mineralizations in SAB, which are associated with Eocene to Miocene intrusions, while the older middle Jurassic-early Cretaceous and upper Cretaceous epochs of SAB [6] have no reported counterparts in Iran. The first epoch of NW Iran postdates all Eocene mineralizations in SAB. The second epoch is coeval with Paragachay and the first-stage of Kadjaran PCDs. The third epoch is younger than all mineralizations in SAB, except the second stage of Kadjaran PCD. These epochs are older than nearly all PCDs and prospects in Central and SE Iran, revealing an old to young trend along the UDMA.

References
[1] Simmonds, V., and Moazzen, M. (2015) Re–Os dating of molybdenites from Oligocene Cu–Mo–Au mineralized veins in the Qarachilar area, Qaradagh batholith (northwest Iran): implications for understanding Cenozoic mineralization in South Armenia, Nakhchivan and Iran. International Geology Review, 57, 290–304.

[2] Simmonds, V., Moazzen, M., and Mathur, R. (2016) Investigation on the age of mineralization in the Sungun porphyry Cu-Mo deposit, NW Iran with a regional metallogenic perspective. EGU General Assembly, 2016, Vienna.

[3] Simmonds, V., Moazzen, M., and Selby, D. (2017) Re-Os dating of mineralization in Siah Kamar porphyry Mo deposit, NW Iran and investigating on its temporal relationship with porphyry Cu-Mo deposits in the southern Lesser Caucasus, NW and central Iran. EGU General Assembly, Vienna.

[4] Aghazadeh, M., Hou, Z., Badrzadeh, Z., and Zhou, L. (2015) Temporal–spatial distribution and tectonic setting of porphyry copper deposits in Iran: constraints from zircon U–Pb and molybdenite Re–Os geochronology. Ore Geology Reviews, 70, 385–406.

[5] Hassanpour, S., Alirezaei, S., Selby, D., and Sergeev, S. (2015) SHRIMP zircon U–Pb and biotite and hornblende Ar–Ar geochronology of Sungun, Haftcheshmeh, Kighal, and Niaz porphyry Cu–Mo systems: evidence for an early Miocene porphyry-style mineralization in northwest Iran. International Journal of Earth Sciences, 104, 45-59.

[6] Moritz, R., Rezeau, H., Ovtcharova, M., Tayan, R., Melkonyan, R., Hovakimyan, S., Ramazanov, V., Selby, D., Ulianov, A., Chiaradia, M., and Putlitz, B. (2016) Long-lived, stationary magmatism and pulsed porphyry systems during Tethyan subduction to post-collision evolution in the southernmost Lesser Caucasus, Armenia and Nakhitchevan. Gondwana Research, 37, 465-503.

2D elemental mapping of pyrite by LA-ICP-MS: an application in visualizing Au enrichment process

Lingli Zhou¹, Balz Kamber¹, Guotao Sun² and Qingdong Zeng^2
1Irish Centre for Research in Applied Geology, Geology Department, Trinity College Dublin, ²Institute of Geology and Geophysics, Chinese Academy of Sciences
Pyrite is commonly associated with mineralization in deposits forming in different environments. The spatial distribution of trace metals in pyrite can be heterogeneous, and may contain genetic information. With the development of 2D trace element mapping with Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) it is now possible to reveal, in much greater detail, the interior compositional textures of pyrite, and thus permit investigation of the mineralisation process that recorded in the crystallization history of pyrite.

Here we report two cases of 2D elemental mapping of pyrite in investigating Au mineralisation process. Pyrite samples were collected from a quartz pebble conglomerate of the fluvial Mississagi Formation, Canada (the basal part is Au abundant), and from the Qingchengzi Pb-Zn-Au-Ag ore field, NE China, respectively. The trace element maps reveal a common existence of core-rim structure for the pyrite from Mississagi Fm. The detrital origin of pyrite is readily demonstrated from rounding of individual grains and cores and the revealed truncated texture of originally rounded detrital fragments. Gold is finely dispersed in the detrital cores/grains, indicating a significant amount of Au was suspended in the river flows for the enrichment. Two distinct episodes of gold enrichment are distinguished from the element maps of pyrite from the Qingchengzi Pb-Zn-Au-Ag deposits: an early syn-sedimentary stage when invisible gold is concentrated in diagenetic pyrite, and maybe re-mobilized and re-concentrated later; and a later hydrothermal stage where gold forms as either free gold grains, or as invisible gold in the pyrite.

                       POSTER PRESENTATIONS                    

REE-enrichment in Palaeoproterozoic banded iron formations, Bergslagen, Sweden: primary precipitation or hydrothermal overprint?

Marcus Brismo-Ploetz¹, Karin Högdahl² and Erik Jonsson^3
1Department of Earth Sciences, Uppsala University, Villavägen 16, SE-75236 Uppsala, Sweden, ²Dept. Earth Sciences, Uppsala University Sweden and Geology and Mineralogy, Åbo Akademi University,, ³Geological Survey of Sweden, Uppsala, Sweden and Dept. Earth Sciences, Uppsala University, Sweden
In the Svecokarelian bedrock of south central Sweden, and specifically, the Bergslagen ore province, hematite-dominated banded iron formations (BIF) constitute one of three major types of iron oxide deposits. Recently, due to the increased criticality of rare earth elements (REE) through their applications in modern industrial and low-carbon/energy saving technologies, several projects have been undertaken to explore their potential distribution in previously unknown deposits and deposit types. Among the resulting discoveries were REE-mineralised BIFs (e.g. Jonsson & Högdahl 2013). In the Högfors mines, silicate-dominated [e.g. cerite-(Ce) and Fe-analogue of västmanlandite-(Ce)] REE mineralisation was interpreted to have formed from epigenetic processes resulting in localised REE-enriched skarn replacing carbonate interlayers, i.e. a post-depositional hydrothermal overprint. Subsequent sampling and analytical work revealed REE-enrichment in other BIF deposits in this part of Bergslagen, e.g. at the Nya Bastnäs field (8500 ppm REE_tot), Storgruvan (1300 ppm REE_tot), and Myrbacksfältet (8000 ppm REE_tot). The main REE hosts here are allanite-(Ce), REE-enriched epidote, and cerite-(Ce). These deposits are located in close vicinity to REE-rich skarn deposits in the REE-line (Jonsson & Högdahl 2013), but REE-anomalous BIFs have also been identified outside of this area. The BIF at Forsbo, located further to the north, has a REE_tot of 1800 ppm, mainly hosted by monazite-(Ce). A post-depositional, epigenetic, yet pre-tectonic origin for the the REE-enrichment in the BIFs along the REE-line is suggested by geological, mineralogical and textural evidence. The phosphate-hosted REE mineralisation in the Forsbo BIF, on the other hand, appears to potentially having formed through primary precipitation.

References
Jonsson, E. & Högdahl, K. 2013: New evidence for the timing of formation of Bastnäs-type REE mineralisation in Bergslagen, Sweden. In: E. Jonsson et al. (eds.), Mineral deposit research for a high-tech world, Proceedings of the 12^th biennial SGA Meeting, 1724-1727.

Characterisation of the Kivilompolo Molybdenum Mineralisation, Peräpohja Belt, Northern Finland

Matthew Goode¹, Jukka-Pekka Ranta², Holger Paulick³ and Eero Hanski^4
1University of Oulu, MSc Student, ²University of Oulu, Doctoral Student, ³University of Oulu, Professor of Economic Geology, ⁴University of Oulu, Oulu Mining School Dean of Education
The Paleoproterozoic supracrustal Peräpohja Belt hosts several poorly studied metal occurrences. One of these includes the Kivilompolo molybdenite mineralisation, initially discovered in the 1950´s. Mineralisation occurs in boudinaged quartz veins within gneissic granites adjactent to the 1.99Ga pre-orogenic Kierovaara granite (Ranta et al. 2015). The ore minerals consist of abundant, coarse grained molybdenite flakes, in addition to pyrite, pyrrhotite and chalcopyrite. Mineralisation occurs in a roughly 3km long zone and, based on drillholes, extends to a depth of at least 150m (Yletyinen 1967).

Preliminary single molybdenite Re-Os dating of the mineralisation gives an age of 1.99Ga (Holly Stein pers.comm), which is consistent with the adjacent Kierovaara granite. The precise age of the host granite is not known, but the close proximity of the Kierovaara granite would suggest a similar age. Discovery of high-grade Palokas Au and Rompas Au-U mineralization in the Peräpohja Belt has given impetus to study this occurrence.

Combined outcrop and boulder mapping was carried out in June of 2017 in order to determine the extent of the mineralised zone. Detailed petrographical analysis of the host rock and mineralised zone will be carried out to better understand the nature of the occurrence and the relationship between deformation and the mineralisation. Whole rock analysis of a number of channel samples will be carried out to determine the presence or absence of a mineralised halo around the deposit. U-Pb dating of zircon from the host rock will provide a precise control on the age of the mineralisation.

References
Ranta JP, Lauri LS, Hanski E, Huhma H, Lahaye Y, Vanhanen E (2015) U-Pb and Sm-Nd isotopic constraints on the evolution of the Paleoproterozoic Peräpohja Belt, northern Finland. Precambrian Res 266:246–259

Yletyinen V (1967) Ylitornion Kivilompolon molybdeenihohde-esiintymästä. Geoteknillisiä julkaisuja N:o 73, Geologian Tutkimuslaitos.

Au-Ag-(Bi-Te-Se)-enriched polymetallic vein mineralisations in SW Sweden: ore mineralogy and thermal evolution

Erik Jonsson¹ and Too little space in box above for SECOND affiliation!
¹Geological Survey of Sweden, Department of Mineral Resources, Box 670, SE-75128 Uppsala, Sweden,
Polymetallic Au-Ag-(Te-Se)-bearing quartz (-carbonate) veins formed in association with large-scale crustal deformation processes during the c. 1 Ga Sveconorwegian orogeny and its aftermath are widespread in SW Sweden, chiefly in Dalsland and Värmland. Previously, ore mineralogical data have been reported for some Värmland veins (cf. Alm & Sundblad 1994, Alm 2000, and references therein), whereas information on the Dalsland veins has been overall lacking. The present study forms part of an attempt to increase the knowledge of the noble and critical metals-rich deposits in this region; within this framework, new observations from the Värmskog veins were also supplied by Nysten (2013).

In most of the studied deposits, the occurrence of Ag-Bi-Te-Se-rich minerals is interpreted to mainly represent unmixing during cooling of a higher-T sulphide phase carrying abundant trace metals; mostly represented by bornite, but also galena, chalcocite and chalcopyrite. Observations, including the presence of exsolved Bi-rich minerals such as wittichenite (Cu₃BiS₃) and miharaite (Cu₄FePbBiS₆) suggest such high initial temperatures; Bi-rich bornites able to exsolve such phases have been termed “bismuth-saturated” and form >400°C (cf. Cook et al. 2011). The identification of accessory ore minerals (and textures) such as altaite (Ag₂Te), argentopyrite-sternbergite (AgFe₂S₃), clausthalite (PbSe)-galena solid solutions, empressite (AgTe), hessite (Ag₂Te; both twinned and untwinned), Hg-amalgams, jalpaite (Ag₃CuS₂)-galena intergrowths, matildite (AgBiS₂) in galena, mckinstryite [(Ag,Cu)₂S], native tellurium, naumannite (Ag₂Se)-sulphide intergrowths, stibnite (Sb₂S₃), stromeyerite (AgCuS), petzite (AuAg₃Te₂) reaction rims, and uytenbogaardtite (Ag₃AuS₂) combine to reveal an extensive evolution at decreasing temperatures, from above and around 300°C, to below 100°C.

References
Alm, E. 2000: Sveconorwegian metallogenesis in Sweden. Medd. från Stockholms univ. inst. f. geol. geok. 307, 17 pp.

Alm, E. & Sundblad, K. 1994: Sveconorwegian polymetallic quartz veins in Sweden. N. Jahrb. f. Min., Mh 1994, 1, 1-22.

Cook, N. J., Ciobanu, C. L., Danyushevsky, L. V. & Gilbert, S. 2011: Minor and trace elements in bornite and associated Cu-(Fe)-sulfides: a LA-ICP-MS study. Geochim. Cosmochim. Acta 75, 6473-6496.

Nysten, C. 2013: Malmmineralogisk undersökning av Pb-, Zn-, Cu- och Ag-förande kvartsgångar i Värmskogsområdet, mellersta Värmland. Examensarbete, Inst. för Geovetenskaper, Uppsala Universitet 254, 83 p.

Crustal structure and hosting lithology account for the spatial distribution of gold mineralisation in SW Finland

Jaakko Kara¹, Tuomas Leskelä¹, Iiro Pitkälä¹, Janne Hokka², Pietari Skyttä¹, Markku Tiainen², Hanna Leväniemi² and Markku Väisänen^1
1Department of Geography and Geology, University of Turku, ²Geological Survey of Finland
New gold occurrences have been recently discovered in the Häme Belt, southwestern Finland (Grönholm and Kärkkäinen 2012, Tiainen et al. 2017). The Geological Survey of Finland and the University of Turku launched a two-year collaborative project to investigate the link between the spatial distribution of the gold mineralisations, the regional-scale bedrock structure and the hosting lithologies. The project also aims at training young geoscientists within the field of economic geology.

Two months of field work carried out in the western part of the study area in 2017 concentrated on structural mapping to characterize the kinematics of the major N-S and E-W trending shear zones, and structural and lithological mapping of the Uunimäki gold mineralization (Kärkkäinen et al. 2016), located close to the intersection of the shear zones. Moreover, conducted mapping and sampling of mafic intrusive rocks provides material to study the geochemical signatures and fertilities of mafic rocks which seem to host several known gold mineralizations in the target area.

The next stage of the project involves U-Pb age determinations to date the gold-hosting intrusive rocks and the shear zone activities, and shifting of the spatial focus on the central and eastern part of the Häme Belt. Thematically, we will apply the methods of prospectivity analysis to understand the exploration potential for gold mineralisations within the area.

References

Grönholm, S. and Kärkkäinen, N., (eds.) 2012. Gold in Southern Finland: Results of GTK studies 1998-2011. Geological Survey of Finland, Special Paper 52, 276 p.

Kärkkäinen, N., Koistinen, E., Huotari-Halkosaari, T., Kuusela, J., Muhammad, S. and Huhta, P., 2016. Uunimäki gold deposit at Huittinen, Southwest Finland. Geological Survey of Finland, Report 77/2015, 54 p.

Tiainen, M., Kujala, S., Ahtola, T., Eilu, P., Grönholm, S., Hakala, O., Istolahti, P., Jumppanen, A., Kärkkäinen, N., Rasilainen, K. and Törmä, H., 2017. Kanta-Hämeen potentiaalisten kaivosten aluetaloudelliset vaikutukset. Summary: Regional economic impacts of potential mining in Kanta-Häme. Geological Survey of Finland, Report of Investigation 229, 124 p.

Accessory minerals within the SAM – a preliminary case study

Michal Ruszkowski¹ and Janina Wiszniewska^2
1Department of Geology, University of Warsaw, Żwirki i Wigury 93, 02-089 Warsaw, ²Polish Geological Institute -National Research Institute, Rakowiecka 4, 00-975 Warsaw
Suwalki Anorthosite Massif (SAM) is a part of Mesoproterozoic, beltiform magmatic AMCG [anorthosite – mangerite – charnokite – granite rapakivi] suite known as a Mazury Complex (Wiszniewska J., 2002). Fe-Ti-V large ore deposits were established within SAM. Nanoconcentrations of REE (La, Ce, Nd), PGE, Au and zircon minerals are often present in sulphide Fe-Cu-Co-Ni dispersed mineralisation. Their size ranges from 10-150 µm or in some cases up to 250 µm.

Hydrothermal concentrations of unusual zirconium elongated forms have been observed within the polymetallic SAM mineralization, suggesting their hydrothermal origin (Bin F., 2009). Zircons form also dispersed grains, which are of igneous origin and thin fillings, filaments and rims around ore minerals. Thin zircon rims are of 80-250 µm in length and 4-30 µm in width and they accurate imitate the shape of ore minerals. The biggest form was observed in untypical zircon form of “blown candle flame” structure. Enrichment of large quantities of Hf (0,5-0,8 mass %) were measured by SEM-EDS method. Wider parts of thin zircon rims around ore minerals were prepared for age determinations and isotopic analyses by SHRIMP IIe machine at PGI in Warsaw.

Numerous small inclusions of Te (0,4-0,7 mass %) were measured in hydrothermal sulphides, especially in millerite. They are grouped in small forms, which are directed along flow of hot solutions. 2-4 µm in size of single inclusions were observed.

New results of accessory minerals in polymetallic mineralisation may increase our knowledge of the evolution of documented SAM.

The research was funded by NCN project 2015/17/B/ST10/03540 and Warsaw University Foundation 21/April/2017.

References:
Wiszniewska, J. (2002). Age and the genesis of Fe-Ti-V ores and related rocks in the Suwałki Anorthosite Massif (Northeastern Poland). Biuletyn PIG. Nr 401.

BinFu, Terrence P. Mernagh, Noriko T.Kita, Anthony I.S. Kemp, John W. Valleya (2009) Distinguishing magmatic zircon from hydrothermal zircon: A case study from the Gidginbung high-sulphidation Au–Ag–(Cu) deposit, SE Australia. Chemical Geology. Vol. 259, Issues 3–4, Pp. 131-142

Platinum Group Element Mineralization of the RF-4 drill core, Reinfjord Ultramafic Complex, Troms, Norway

Lars Tollefsrud^1
1Norwegian University of Science and Technology (NTNU)
The Reinfjord Ultramafic Complex (RUC) is a part of the Seiland Igneous Province (SIP). The SIP is given an age of 560-570 Ma (Roberts et al. 2006), and is a part of the Kalak Nappe Complex. Thus, the SIP is a part of the Middle Allochton of the Caledonian thrust nappe. The RUC comprises rocks that of dunitic, wehrlitic and olivine-clinopyroxenitic composition and is surrounded by metasediments and gabbro. Chemical data of four drill cores from the RUC (RF-1, RF-2, RF-3 and RF-4) display platinum group element (PGE) anomalies in the upper third part of the drill cores.

Detailed work on the PGE mineralization in the RF-1 drill core of the was performed Even Nikolaisen (2016). Nikolaisen discovered that majority of the platinum group minerals (PGM) were present as tellurides hosted by base metal sulfides (BMS).

The writer desires to continue the work by Nikolaisen by investigating the PGM in the RF-4 drill core. The RF-4 drill core is located on the footwall of what is likely to be a normal fault, while the RF-1 drill ore is taken from the hanging wall of the same fault. The writer will investigate the distribution and chemistry of the PGM to gain a better understanding into the ore forming processes. Scanning electron microscopy (SEM) and electron probe micro analyzer (EPMA) will be utilized, as well as transmitted-and reflected light microscopy for studying base metal sulfides. Thermodynamic software such as Perpl_x and MELTS may be used to model stability of silicates and sulfides.

References
Nikolaisen, Even 2016: Platinum Group Elements in the Reinfjord Ultramafic Compex (Master Thesis), Norwegian Univeristy of Science and Technology

Roberts, R.J et al. 2006: Short-lived mafic magmatism at 560–570 Ma in the northern Norwegian Caledonides: U–Pb zircon ages from the Seiland Igneous Province. In: Geological Magazine 143, 887-903