Havs- och vattenmyndigheten har tagit fram föreskrifter om klassificering, miljökvalitetsnormer och bedömningsgrunder avseende ekologisk status av ytvatten där uran klassificeras som ett särskilt förorenade ämne. LKAB som är ett statligt ägt bolag som bedriver gruvverksamheter i Kiruna, Malmberget och Svappavaara har ålagt sig att utreda förekomsten av uran i sitt gruvvatten. Denna studie har sitt fokus på gruvverksamheten i Malmberget där höga koncentrationer av uran har upptäckts i gruvvattnet och källan till detta behöver utredas. Examensarbetet har utförts tillsammans med Luleå Tekniska Universitet och LKAB.  LKAB har utfört vattenprovtagningar i gruvvatten en gång under 2018, 2019 och 2021 varderna samt i bergborrade hål en gång under 2019 samt 2021. Proverna har analyserats efter metaller och isotoper. Gruvvattnet har generellt mycket högre uranhalter. Isotopkvoten 234U/238U har studerats för att spåra källan till uranet och resultaten visar ett flertal källor där fyra övergripande grupperingar kunde påvisas. Även data från borrkärnor har studerats för att jämföra spatiala variationer mellan vattenproverna och de fasta proverna från borrkärnorna. Hypotesen har varit att oxiderat yt- och grundvatten infiltrerar gruvan och lakar ut uran från mineralen uraninit, anhydrit, gips, titanit, apatit, monazit och stilbit. Hypotesen har varit baserad på den litteraturstudie som utförts samt tidigare studier i Malmberget.  Datatolkning inom varje grupp samt visualisering av data har utförts i ioGAS, Leapfrog, QGIS, PHREEQC, Geochemist Workbench och Excel. Resultaten indikerar att de höga koncentrationerna av uran är en följd av gruvverksamheten. Uranet mobiliseras av oxiderat vatten som infiltrerar gruvan från både inras-zoner och naturliga sprickbildningar och transporteras som karbonatkomplex. Projektet har även påvisat att uranförekomsterna i det Västra fältet av Malmberget troligtvis domineras av uraninit medan det Östra fältet troligtvis domineras även av anhydrit, gips och salter. Vidare har de högsta koncentrationerna av uran i berg lokaliserats i granit och pegmatit i samband med hydrotermala zoner i granitisk berggrund. Även malmen har genom SEM-analys påvisats innehålla uranmineral i inneslutningar i titanit. Resultatet har visat att kvoten 234U/238U kan användas som en indikator till olika källor av uran. För att visa vilka mineral som är dominerande och bidragande källor till de höga urankoncentrationerna i Malmbergets gruvvatten behöver mineralogin undersökas mer noggrant och i större omfattning.

This research project investigated the high concentration of sulphate in a tailing pond at LKAB and the characteristics and behavior of sulphate minerals in different areas of the pond. The sampling of the tailings was carried out at Nine stationary sampling points. Each sample was taken from the surface to a depth of one meter except for the underflow sample which was collected from the thickener in the processing plant (fresh tailings). Stereo microscopy and SEM-EDS analysis aid in identifying mineral grains and confirming the presence of Gypsum and/or Anhydrite, along with other minerals like Pyrite, Pyrrhotite, and Chalcopyrite. The difficulty in distinguishing between Gypsum and Anhydrite under SEM was noted due to their similar crystal shapes and chemical composition. Gypsum and/or Anhydrite were identified as the main minerals responsible for the high sulphate concentration based on elemental screening, sequential extraction, and mineralogical results. Sulfide minerals like Pyrite, Chalcopyrite, and Pyrrhotite were also present but did not show any signs of weathering characteristics and therefore probably not contributed to the high sulphate concentration in the pond. The quantitative mineralogy carried out confirmed the presence of Gypsum and/or Anhydrite, Pyrite, Pyrrhotite and Chalcopyrite as identified in the mineralogical analysis. The study concludes that Gypsum and/or Anhydrite are the main contributors to the high sulphate concentration in the LKAB tailings pond.

The Norrbotten region is an important Swedish mining district with occurrence of several economic deposits and sub-economic deposits of apatite iron ores (Kiruna Type) and epigenetic Cu-Au ores. The apatite iron ores include the large Malmberget deposit mined by LKAB company as one of their world class underground mines. The Malmberget ores are hosted by a Paleoproterozoic unit of metavolcanics and metasedimentary rocks intruded by multiple plutonic rocks varying in composition. The rocks at Malmberget are overprinted by intense widespread hydrothermal alteration, metamorphism and deformation. The Malmberget iron deposit is thought to originally be one continuous lens that segmented into more than 20 different orebodies during the regional metamorphism and deformation. The Malmberget deposit is characterized by different orebodies that shows different textures and chemical variations. The iron ores at Malmberget are mainly consisting of magnetite and hematite.   Apatite iron ores of the Kiruna type have raised divergent opinions regarding whether this type of deposits are magmatic or hydrothermal in origin. However, trace element analysis have been used for studies that yield information about ore-forming fluids and mineralizing processes. This paper aims at understanding the vanadium behaviour and distribution in the Malmberget ores as well as studying textural and mineralogical control of vanadium in the iron ores. Learnings from this paper aids in understanding the controls and distribution of vanadium and increasing knowledge regarding genetic aspects of the Malmberget deposit. To achieve this, detailed core logging, optical microscopy, lithogeochemistry and scanning electron microprobe analyses were utilized to figure out why the vanadium content is high in some places and low in other parts of the deposit.  Textural data of both magnetite and hematite ores show that the Malmberget ores can be characterized as massive ore and breccia type. The ores in the western part of the deposit are dominated by metamorphic and oxidation textures, including martitisation textures and triple junction textures. The ores in the eastern part are mainly massive magnetite textures with apatite and amphibole as the main gauge minerals. Metamorphic recrystallization and oxidation of the ores resulted in vanadium redistribution and chemical changes of both hematite and magnetite. Vanadium is high in both magnetite and hematite ore and low in the silicate host rocks. The eastern ore bodies of the deposit are found to be higher in vanadium content compared to those on the western side. Vanadium is high in magnetite ore sections but in magnetite-hematite grain pairs vanadium is redistributed from the magnetite grain to the adjacent hematite grain during metamorphic oxidation and recrystallization of magnetite. The results from this project suggest that a better understanding of what controls the distribution of vanadium in the ores needs more investigations regarding element partition under different geochemical conditions. There are also uncertainties regarding the initial source of vanadium and its primary distribution in different minerals and ore types and later redistributions. The origin of hematite in the ores and the stratigraphic position of the ores are other aspects that needs further studies to get a deeper understanding of the behaviour of vanadium in the Malmberget deposit.

The mining industry produces massive amounts of waste that without treatment and in contact with oxygen can result in acid rock drainage (ARD) and increased leaching of metals. In Sweden, the common way to manage the mine waste after closure is to apply a dry coverage on top of the waste deposition. The access to a suitable cover-material is however limited and can lead to extensive costs for the mining company. This creates a great driving force for alternative solutions, e.g. bentonite amendment to till. However, bentonite production is costly both economically and environmentally due to time- and resource- consuming production. Recycling of industrial residues as a cover material is another option. The recycling is beneficial for many parts, i.e. the industry producing the residue, the mining industry that will use the residue and the society in its strive for zero waste. An industrial residue that has potential to improve the sealing layer qualities of a local till is Green Liquor Dregs (GLD), a residue from pulp production in a paper mill. In this study 5 to 20 wt. % of GLD from two different paper mills, with varying total solid content (TSC) and particle size distributions (PSD), were mixed with three tills also with varying PSD and TSC. The objectives of the study were to investigate if GLD addition can improve a till so it can be used in a sealing layer, how the fines- and clay content in the tills affects the hydraulic conductivity (HC) and the water retention capacity (WRC) of the till-GLD mixtures, and how the initial water content will affect the HC in the different mixtures. The HC of the mixtures based most of the tills studied improved, but not enough to reach the required 10-8 m/s. Only the material based on a more clayey silty till had an HC below 10-8 m/s, even if it increased with the addition of GLD. The WRC, on the other hand, shows promising results, especially for 15 wt. % GLD addition. An increase in WRC is seen the more GLD is added. However, due to compaction difficulties more than 20 wt. % addition is not recommended. There is a difference in both HC and WRC between the mixtures based on the different tills, and a characterization of the till as a bulk material and its mixture with GLD is suggested before using it in mine remediation purposes. The HC of the till is affected by the content of fines and especially clay. The results from the WRC is more complicated and a mineralogical study on the GLD and the clay fraction of the tills is recommended. This study also shows that the initial water content of the materials rather than dry density has an impact on the HC of the mixtures. The initial water content determines the degree wet of optimum that in this and previous studies has shown to greatly affect the HC. A drier till and GLD leads to that more GLD should be added to the mixture when reaching for optimal HC. Even if the study did not result in low enough HC in most of the cases, the WRC shows promising results and is the most important parameter minimizing the oxygen diffusion to the mine waste. The greatest challenge when working with GLD is, however, its heterogeneity which makes it difficult to predict how it will behave in a sealing layer. Even though, the recycling of GLD in mine waste remediation should be strived for as it is beneficial for both the industry that provides the residue and the mining company. It is also a great profit for the environment as it minimizes the waste disposed and reduce use of natural resources.

The naturally occurring isotopes 231Pa and 230Th are used as tracers of marine biogeochemical processes. They are both produced from the radioactive decay of their uniformly distributed uranium parents (235U and 234U) in seawater. After production, 231Pa and 230Th are removed by adsorption onto settling particles (scavenging) and subsequently buried in marine sediments. 230Th is more particle reactive compared to 231Pa. Consequently, 230Th will be removed from the open ocean by adsorption onto settling particles, while 231Pa tend to be laterally transported by currents and removed by scavenging in areas of high particle flux (e.g. ocean margins). The primordial 232Th indicates lithogenic supply via rivers and resuspension of sediments, which provides additional information about processes involved in the cycling of particle reactive elements in the ocean. The preferential deposition of particle reactive elements at ocean margins (boundary scavenging) has important implications for our understanding of the distribution and dispersion of micronutrients (e.g. iron) and pollutants in the ocean. It is therefore valuable to understand the nature of boundary scavenging processes in order to evaluate the relative contribution of circulation and scavenging behaviors.The major characteristics of thermohaline circulation in the Mediterranean are well known and have been studied for decades. This sea is an almost land-locked area, where limited water-exchange with the Atlantic Ocean only occurs through the Strait of Gibraltar. Therefore, this marginal sea is often referred to as a “miniature ocean” suitable as a “laboratory” for marine environmental research. In this licentiate thesis, distributions of 231Pa, 230Th and 232Th in seawater and marine particles collected during the GEOTRACES MedSeA-GA04-S cruise in 2013 are presented. Observed nuclide distributions indicate the impact of deep water formation processes, where observed differences can be linked to the type of deep water formation process that occurs in respective basin. Essentially all in-situ produced 230Th is buried in Mediterranean Sea sediments. Despite lower affinity of 231Pa for marine particles, most 231Pa is also scavenged and deposited in Mediterranean Sea sediments. The efficient scavenging of 231Pa produces a relatively low fractionation between 231Pa and 230Th in terms of the fractionation factor FTh/Pa. This licentiate thesis presents a summary of the methods used for the analysis of 231Pa and Th-isotopes with details on the exchange chromatography method and the treatment of mass spectrometric data. The study of 231Pa, 230Th and 232Th in the Mediterranean Sea has important implications for our understanding of processes that control their water column distributions and how their behavior can be utilized to trace chemical flux in modern and past ocean environments. / GEOTRACES / MeDSeA

The specific surface area, determined by the BET method, is a parameter often used to scale results of mineral studies of surface reactions in terms of rate and capacity to the field scale. Such extrapolations of results from small-scale laboratory experiments to the field-scale are important within many environmental applications. An example of this is for the prediction of radionuclide retention in the bedrock surrounding a deep repository for radioactive waste, following failure of the engineered barriers, where radionuclides may sorb onto minerals constituting the geological environment. As a first step, the approach used in this work is to study the relationship between specific surface area and the particle size (0.075-8 mm) and to approach the field scale via measurements on large, centimetre-sized pieces, for seven natural minerals commonly found in granite: apatite, biotite, chlorite, K-feldspar, hornblende, labradorite and magnetite. The underlying assumption is that sorption of radionuclides can be related to specific surface area of a particular mineral in a continuation of this project.The results show that the phyllosilicates biotite and chlorite have a specific surface area that is about 10 times larger than the other minerals. Over the range of particle size fractions studied, the specific surface area varies between 0.1 and 1.2 m2g-1 for biotite and chlorite. The other studied minerals have specific surface areas varying between 0.01 m2g-1 for the largest fraction and up to 0.06 - 0.12 m2g-1 for the smallest. Results show linear relationships between the specific surface area and the inverse of the particle size for all studied minerals for small particle sizes, as expected. For some minerals, however, the data seemingly can be divided in two linear trends, where a change in internal surface area, surface roughness and/or particle geometry as the particle size decreases may explain this behaviour. Interestingly, for larger particles, there is a deviation from the linearity observed for small particles. Tentatively, this behaviour is attributed to a disturbed zone, created by the mechanical treatment of the material during particle size reduction, extending throughout small particles, but not altering an undisturbed core of the larger particles. In agreement with this, measurements on large pieces show a surface area 5 to 150 times lower than expected from the linear trends observed for the crushed material, implying an overestimation of the surface area and possibly also of the sorption capacities of the rock material from simple extrapolations of experimental results employing finely crushed material to the field situation. / QC 20110929 / Äspö Radionuclide sorption

Zinkgruvan is a stratiform Zn-Pb-Ag deposit located in the Bergslagen ore district in south central Sweden. Elevated concentrations of cobalt have been detected in zinc ore from the mine. Cobalt is one of EU’s critical raw materials, since cobalt is mainly mined in politically unstable countries like Congo and is an important metal needed in batteries for modern technology, e.g., electrical cars. However, elevated contents of cobalt can also cause problems during smelting of zinc ore and lower the value of zinc concentrates. Knowledge of the mineralogical deportment of cobalt is in this context critical, since accessory cobalt minerals could potentially be separated from zinc concentrates, whereas lattice-bound cobalt in sphalerite will follow the latter throughout the processing chain. In this study, the mineralogical distribution in zinc ore from three different main areas of Zinkgruvan (Knalla, Nygruvan and Westfield) has been investigated using optical microscopy, whole rock lithogeochemistry, Scanning Electron Microscope (SEM), Electron Microprobe Analysis (EMPA), Quantitative Target Mineralogy (QanTmin) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). The different datasets have been integrated in order to provide quantitative data on cobalt deportment in the samples, and for defining geochemical proxies that can be used to predict the cobalt deportment using only whole rock assay data. For the majority of the samples of this study, the cobalt content in sphalerite is higher than what has been reported in earlier studies of Zinkgruvan and are among the highest globally. In addition, this study provides the first account of high levels of lattice-bound cobalt in pyrrhotite at Zinkgruvan, for some samples being even higher than in sphalerite. Thus, the pyrrhotite could also potentially be separated from the zinc concentrate in order to dispose of some of the cobalt in the samples.  However, for the samples on which cobalt deportment calculations have been made, the results of the calculations suggest that for 50% of the samples most of the whole rock cobalt is lattice-bound to sphalerite, which is by far the predominant mineral in the zinc ore. For the remaining 50% of the samples most of the whole rock cobalt is bound to the cobalt mineral safflorite, which locally forms an important accessory mineral. No sample has the majority of the whole rock cobalt in pyrrhotite, reflecting the generally minor contents of this mineral in the zinc ore. In general, there is more lattice-bound cobalt in pyrrhotite and sphalerite in samples from Westfield and more cobalt bound to cobalt minerals in samples from Knalla. Samples from Nygruvan have very low whole rock cobalt contents altogether and contain no cobalt minerals. These spatial variations support ore genetic zonation models presented by earlier studies, with increasing Zn/Pb ratios and decreasing cobalt content in zinc ore from proximal to distal, in relation to an old hydrothermal vent zone at Knalla. However, the high cobalt and cadmium contents found at Westfield could imply that the vent zone might be more widespread than assumed by earlier studies. / Zinkgruvan är en stratiform Zn-Pb-Ag-malmförekomst som ligger i malmdistriktet Bergslagen i södra Sverige. Förhöjda koncentrationer av kobolt har upptäckts i zinkmalmen från gruvan. Kobolt är en av EU:s kritiska råmaterial eftersom kobolt främst bryts i politiskt instabila länder som t.ex. Kongo och eftersom det är en viktig metall som behövs i batterier för modern teknik, exempelvis elbilar. Förhöjda halter av kobolt kan dock också orsaka extra kostnader och försämrat utbyte vid zinkframställning från zinkmalm, och kan därmed sänka en zinkmalms värde. Kunskap om den mineralogiska fördelningen av kobolt i zinkmalmen är i detta fall avgörande, eftersom accessoriska koboltmineral potentiellt skulle kunna avlägsnas innan smältprocessen, till skillnad från gitterbunden kobolt i zinkblände som följer med zinken i hela utvinningsprocessen. I denna studie har den mineralogiska distributionen i zinkmalm från tre olika huvudområden i Zinkgruvan (Knalla, Nygruvan och Västra fältet) undersökts genom användning av optisk mikroskopering, geokemisk analys av bulkprover, svepelektronmikroskopi (SEM), elektronmikrosondanalys (EMPA), kvantitativ mineralogi (QanTmin) och laserablation-induktivt kopplad plasma-masspektrometri (LA-ICP-MS). De olika dataseten har integrerats för att tillhandahålla kvantitativa data för koboltfördelning i proverna och för att kunna definiera geokemiska kriterier som kan användas för att förutsäga koboltfördelningen med hjälp av endast litogeokemisk analysdata. För majoriteten av proverna i denna studie är koboltinnehållet i zinkblände högre än vad som har rapporterats i tidigare studier av Zinkgruvan, och är bland de högsta globalt. Dessutom tillhandahåller denna studie den första redogörelsen för höga nivåer av gitterbunden kobolt i magnetkis. För vissa prover är det sistnämnda till och med högre än i zinkblände. Således skulle även magnetkisen potentiellt kunna separeras från zinkkoncentratet för att bli av med en del av kobolten i proverna. För de prover där beräkningar på koboltfördelningen har gjorts visar dock resultaten av beräkningarna att för 50% av proverna förekommer merparten av bulkinnehållet av kobolt i malmen som gitterbundet i zinkblände, vilket är det överlägset dominerande mineralet i zinkmalmen. För de resterande 50% av bulkproverna är det mesta av kobolten bundet till koboltmineralet safflorit, som lokalt är ett viktigt accessoriskt mineral. Inget bulkprov har merparten av koboltinnehållet i magnetkis, vilket reflekterar det generellt lägre innehållet av detta mineral i zinkmalmen. I allmänhet finns det mer gitterbunden kobolt i magnetkis och zinkblände i bulkprover från Västra fältet och mer kobolt bundet till koboltmineral i bulkprover från Knalla. Bulkproverna från Nygruvan har väldigt lågt koboltinnehåll överlag, och innehåller inga koboltmineral. Dessa spatiala variationer stödjer malmgenetiska zoneringsmodeller presenterade i tidigare studier, med ökande Zn/Pb kvoter och minskande koboltinnehåll i zinkmalmen från proximal till distal, i relation till en fossil hydrotermal tillförselkanal i Knalla.  Det höga kobolt- och kadmiuminnehållet som detekterats i Västra fältet kan dock antyda att den hydrotermala tillförselkanalen skulle kunna vara mer utbredd än vad som antagits av tidigare studier.

Nutrient dynamics in the Archean-Paleoproterozoic oceans strongly influenced primary productivity and the rise of atmospheric O2. Reconstructing the cycling of key nutrients such as dissolved inorganic phosphate (DIP) at this time is important for our understanding of the timing, rate and extent of atmospheric oxygenation at this time. Banded iron formations (BIF) can be used as proxies for global DIP content in Precambrian marine waters. Estimating Precambrian DIP requires understanding of the mechanisms by which Fe(III)(oxyhydr)oxides scavenge DIP which has come mainly from experimental studies using NaCl solutions that mimick Precambrian marine conditions with for example, elevated Si and Fe(II) concentrations. The two DIP binding modes suggested for Early Proterozoic marine waters are 1) Adsorption - surface attachment on pre-formed Fe(III) (oxyhydr)oxides, and 2) Coprecipitation - incorporation of P into actively growing Fe(III) (oxyhydr)oxides. It has been suggested that the elevated Si concentrations suggested for Precambrian seawater, strongly inhibit adsorption of DIP in Fe(III)(oxyhydr)oxides. However recent coprecipitation experiments show that DIP is strongly scavenged by Fe(III)(oxyhydr)oxides in the presence of Si, seawater cations and hydrothermal As. In this study we show that the DIP uptake onto Fe(III)(oxyhydr)oxides by adsorption is less than 5% of that by coprecipitation. The data imply that in the Early Proterozoic open oceans, the precipitation of Fe(III)(oxyhydr)oxides during mixing of deep anoxic Fe(II)-rich waters with oxygenated ocean surface waters caused DIP removal from surface waters through coprecipitation rather than adsorption. Local variations in DIP and perhaps even stratification of DIP in the oceans were likely created from the continuous removal of DIP from surface waters by Fe(III)(oxyhydr)oxides, and its partial release into the anoxic bottoms waters and in buried sediments. In addition to a DIP famine, the selectivity for DIP over As(V) may have led to As enrichment in surface waters both of which would have most likely decreased the productivity of Cyanobacteria and O2 production. / Näringscirkulationen i haven under arkeikum och paleoproterozoikum påverkade primärproduktionen och uppkomsten av atmosfärisk syrgas (O2). För att förstå när och hur fort koncentrationen av O2 i atmosfären ökade behöver vi rekonstruera hur viktiga näringsämnen, t.ex. löst oorganiskt fosfor (engelska “Dissolved Inorganic Phosphorous”, DIP) cirkulerade. Bandad järnmalm (engelska “Banded Iron Formations”, BIF) kan användas som en markör för DIP i de prekambriska haven. För att kunna använda DIP som markör måste man förstå hur prekambrisk DIP tas upp av järn(III)(oxyhydr)oxider. Hittills har detta studerats med natriumkloridlösningar som ska efterlikna förhållande i de prekambriska haven, med t.ex. förhöjda kisel- och järn(II)-koncentrationer. Ur sådana studier har två bindningsmekanismer föreslagits för paleoproterozoiskt havsvatten 1) Adsorption, d.v.s. DIP binds till ytan på redan bildade kristaller av järn(III)(oxyhydr)oxid, och 2) samutfällning, d.v.s. upptag av fosfor i kristaller av järn(III)(oxyhydr)oxid medan kristallerna bildas. Det har föreslagits att de höga kiselkoncentrationerna som tros ha funnits i de prekambriska havsvattnet hämmade adsorption av DIP på ytan av järn(III) (oxyhydr)oxidkristaller. Men de senaste samutfällningsexperimenten tyder på att järn(III) (oxyhydr)oxid effektivt tar upp DIP även i närvaro av kisel, arsenik från hydrotermala källor och de katjoner som dominerar i havsvatten. I här presenterad studie var mängden DIP som bands till järn(III)(oxyhydr)oxidkristaller genom adsorption mindre än 5 % av den DIP som togs upp av kristallerna via samutfällning. Våra data tyder på att när järn(III) (oxyhydr)oxid fälldes ut i tidiga-proterozoiska hav när järn(II)-rikt djupvatten blandades med syrerikt ytvatten, och att DIP avlägsnades från ytvattnet genom samutfällning snarare än adsorption. Lokala variationer av DIP-koncentrationer i haven, möjligen även skiktning, kan ha orsakats av kontinuerlig utfällning av järn(III)(oxyhydr)oxider ur ytvattnet följt av partiell frigörelse av DIP i syrefria djupvatten och sediment. Kristallisationsprocessen, som gynnar inbindning av DIP och misgynnar inbinding av arsenik (V) kan ha orsakat brist av DIP och anrikning av arsenik i ytvattnet, vilket troligen minskade tillväxten av cyanobakterier med lägre syrgasproduktion som följd. / CLAPO

Located at an important intersect between orogenic Au deposits in Sweden’s Gold Line and volcanicmassive sulphide (VMS) deposits in the Skellefte Mining District, the Barsele area is of high interest.Currently, the Barsele deposit consists of the Norra VMS deposit and 3 intrusive-hosted orogenic Audeposits: Avan, Central, and Skiråsen which are hosted in a 1876 ± 10 Ma early orogenic granodiorite(Thomas, et al., 2019). The aim of this thesis is to create a structural and geological model of the Barsele area whilst improvingthe understanding of the structural controls on VMS and intrusive-hosted Au mineralisation in thearea. Furthermore, this thesis aims to highlight prospective areas for future study and targeting inhopes to aid mineral exploration in the region. Geological mapping has been carried out in an area ofaround 440km2, with emphasis on structural measurements. 381 outcrop observations and more than4200 structural features were recorded using a combination of traditional and digital mappingmethods, including the use of Field Move by Petroleum Experts. The area was chosen as part of AgnicoEagle, Sweden’s mineral exploration project. The region has been affected by two dominant, syn-metamorphic cleavage forming events. The eventsdefine the main phase of the Svecofennian Orogeny which has produced ubiquitous slaty cleavage, Ndirected thrusts, and steeply inclined axial surfaces throughout the region. The region is characterisedby important N-S displacements with sinistral movement along major N-S trending transfer faults. Theabsence of strike-slip shearing in D1 structures indicates that D1 deformation was dominantly coaxialin nature and developed due to SW-NE crustal shortening. Along with this, a major ESE-WNW-strikingshear zone is identified with an inferred syn-extensional (D1) origin. D2 involved fault inversion and reactivation of syn-extensional faults as reverse shear zones. E-Wtrending lineations along more brittle SSW-NNE striking shear zones inferred to indicate an E-Worientation for crustal shortening during D2. D3 caused reactivation of the N-S-striking high-strain zones with reverse kinematics. This reactivationof trending shear zones resulted in strain partitioning into N-S zones. D3 is manifested by broad, open,N-NE trending upright folds of bedding and S2 foliation. 1st, 2nd, and 3rd order D3 structures have beencharacterised and illustrated by combining a range of data including outcrop observations, regionalStereonets, magnetic anomaly maps, and other geophysical maps.

Samhället står inför stora utmaningar för att lyckas nå målet i Parisavtalet om att begränsa den antropogena uppvärmningen till 1,5˚C samt det nationella klimatmålet om att uppnå netto-noll-utsläpp av växthusgaser senast år 2045. Geologisk lagring av koldioxid (CCS, Carbon Capture and Storage) lyfts fram som en nyckelåtgärd för att reducera koldioxidutsläppen och därigenom uppnå dessa mål. Totalt beräknas ca. 2700 CCS-projekt behövas år 2050, vilket är en signifikant ökning från dagens 27 anläggningar. Bio-CCS, eller BECCS (Bio-Energy with Carbon Capture and Storage) är en CCS-teknik där koldioxid som bildas som en industriell biprodukt fångas in och lagras. Koldioxiden kan till exempel fångas in vid förbränning av biomassa i massa- och pappersbruk. På senare år har en ny geologisk lagringsmetod utvecklats där man lagrar koldioxid genom att bilda stabila karbonatmineral in situ. In situ-karbonatisering utmanar i allra högsta grad den hittills dominerande lagringsmetoden där lagring av koldioxid sker i sedimentär berggrund. När koldioxid lagras i sedimentär berggrund tar det tusentals år för koldioxiden att bilda karbonatmineral, vilket kan jämföras med in situ-karbonatisering där det visat sig ta <2 år att uppnå samma resultat. Karbonatisering påskyndar en naturlig process som sker när kol lagras i marken och utnyttjar därmed bergartens befintliga egenskaper.  Ultramafisk och mafisk berggrund med högt innehåll av tvåvärt järn (Fe2+), kalcium (Ca2+) och magnesium (Mg2+), har visat sig vara lämpade för in situ-karbonatisering. Fram tills nu har potentialen för in situ-karbonatisering aldrig undersökts i Sverige. Detta arbete syftar därför till att karaktärisera mafiska bergarter baserat på deras teoretiska potential att lagra koldioxid genom in situ-karbonatisering, vilket gjorts genom att studera mineralogin och geokemin av olika bergarter från lokaliteter på Alnön, öster om Sundsvall och runt Nordingrå utanför Örnsköldsvik samt områden i närheten av Örnsköldsvik. Det här arbetet är en del av forskningsprojektet INSURANCE som finansieras av Energimyndigheten och syftar till att utvärdera potentialen för bio-CCS i den svenska berggrunden. Resultatet påvisade mineralogiska och geokemiska likheter mellan de provtagna områdena och basalt som visat sig vara lämplig för koldioxidlagring. En del av proverna uppvisar dock tecken på omvandling vilket är påverkar reaktionen negativt. Därför är det främst de lokaler som uppvisar låg omvandlingsgrad som rekommenderas för vidare undersökning. Proverna innehåller mineral som har potential att fungera för in situ-karbonatisering. Det behövs dock ytterligare undersökningar för hur dessa bergarter reagerar med koldioxiden i praktiken (karbonatiseringsexperiment) samt storleken/volymen på en eventuell lagringsplats. / Society faces major challenges to succeed in achieving the goal of the Paris Agreement to limit anthropogenic warming to 1.5°C and the national climate target of achieving zero net emissions of greenhouse gases by 2045. Geological storage of carbon dioxide (CCS, Carbon Capture and Storage) is highlighted as a key action in reducing carbon dioxide emissions and thereby achieve these goals. In total, approx. 2700 CCS projects are needed by 2050, which is a significant increase from today's 27 facilities. Bio-CCS, or BECCS (Bio-Energy with Carbon Capture and Storage) is a CCS technology where carbon dioxide formed as an industrial by-product is captured and stored. The carbon dioxide can, for example, be captured during the combustion of biomass in pulp and paper industries. In recent years, a new geological storage method has been developed where carbon dioxide is stored by forming stable carbonate minerals in situ. In situ carbonation is very much challenging the until now dominant storage method that stores carbon dioxide in sedimentary basins. When carbon dioxide is stored in sedimentary basins, it takes thousands of years for the carbon dioxide to form carbonate minerals, which can be compared to in situ carbonation where it has been shown to take <2 years to achieve the same result. Carbonation accelerates a natural process that occurs when carbon is stored in the soil, thereby utilizing the rock's existing properties. Ultramafic and mafic bedrock with a high content of divalent iron (Fe2+), calcium (Ca2+) and magnesium (Mg2+), have proven to be suitable for in situ carbonation. Until now, the potential for in situ carbonation has not been investigated in the Swedish bedrock. This work therefore aims to characterize mafic rocks based on their theoretical potential to store carbon dioxide through in situ carbonation, which has been done by studying the mineralogy and geochemistry of different rocks from localities on Alnön, east of Sundsvall and around Nordingrå outside Örnsköldsvik and areas near Örnsköldsvik. This work is part of the research project INSURANCE, which is funded by the Swedish Energy Agency and aims to evaluate the potential for bio-CCS in Sweden. The sampled areas show mineralogical and geochemical similarities to basalt which has been proven to be suitable for carbon dioxide storage. However, some of the samples show signs of alteration, which affects the reaction negatively. Therefore, it is mainly those localities that show a low alteration rate that are recommended for further investigation. The samples contain mineral that has the potential to function for in situ carbonation. However, further studies are needed on how these rocks react with carbon dioxide in practice (carbonation experiment) and to evaluate the size/volume of the possible storage site.