| 1. |
- Andersson, Joel B.H., et al.
(author)
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U-Pb zircon-titanite-apatite age constraints on basin development and basin inversion in the Kiruna mining district, Sweden
- 2022
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In: Precambrian Research. - : Elsevier. - 0301-9268 .- 1872-7433. ; 372
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Journal article (peer-reviewed)abstract
- To constrain the tectonothermal evolution of the type locality for iron oxide-apatite deposits, we have obtained U-Pb zircon, titanite, and apatite age data for the Kiruna mining district in northernmost Sweden. The results indicate that the host basin initiated in an overall extensional regime as indicated by the deposition of alluvial conglomerates and greywackes. A volcanic intercalation in a conglomerate unit northwest of the Luossavaara iron oxide-apatite deposit yields a U-Pb zircon age of 1887 ± 3 Ma representing the timing of the earliest Orosirian volcanism in the central Kiruna mining district coinciding with the onset of basin development. In-situ analysis of titanite on hydrothermally altered fracture planes within a cataclastic fault damage zone (c. 270 m from the fault core system associated to the Luossavaara iron oxide-apatite deposit) yields complex U-Pb data. Applying a strict discordance filter yields a 207Pb/206Pb age of 1889 ± 26 Ma. The age implies that the fault probably has a syn-volcanic origin and that syn-volcanic faults may have played an important role during iron ore emplacement. The mineralized basin was subsequently buried and metamorphosed under upper greenschist-facies conditions and later tectonically exhumed and cooled below the apatite closure temperature at 1805 ± 26 Ma indicated by apatite from the Nukutus iron oxide-apatite deposit. Basin inversion is temporally constrained by syn-tectonic titanite as part of sodic-calcic + Fe + Cl hydrothermal alteration along a brittle-ductile reverse shear zone to the east of the study area. Titanite grains that show sector and oscillatory zoning yield an age of 1812 ± 3 Ma, which we interpret as the onset of basin inversion. Homogeneous (relatively unzoned) titanite in the same sample yields an age of 1802 ± 8 Ma, tentatively indicating that the tectonothermal activity lasted up to c. 20 m.y.
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| 2. |
- Bauer, Tobias E., Associate professor, 1982-, et al.
(author)
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Analysis of data from Unmanned Aerial Systems (UAS) in a Virtual Reality environment
- 2019
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In: Proceedings of the Visual3D conference 2019, 1–2 October 2019, Uppsala, Sweden: Visualization of 3D/4D models in geosciences, exploration and mining. - : Luleå University of Technology. ; , s. 19-19
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Conference paper (peer-reviewed)abstract
- The use of Unmanned Aerial Systems (UAS) is getting increasingly popular for many different types of applications. The field of geology is slowly catching up resulting in new and innovative UAS solutions for various kinds of airborne measurement techniques. These techniques comprise a wide range of geophysical and remote sensing methods used to investigate the sub-surface. At Luleå University of Technology two different types of UAS are used in combination with a Virtual Reality environment in order to analyze geological structures and related ore deposits and mineralizations. The two UAS comprise a) a custom made quadrocopter (HUGIN) with a pay load of approx. 3.5 kg and an operational time of 5 times (batteries) maximum 35 minutes depending on payload, ambient temperatures and wind speed; and b) a foldable DJI Mavic Pro with an operational time of 3 times 30 minutes. The HUGIN system can be operated with a high-resolution optical camera for photogrammetry surveys and a 3-axial fluxgate magnetometer for measuring magnetic anomalies within bedrock and ultimately delineating geological structures. The system is highly flexible and a thermal camera is currently added to the system in order detect water fluxes in relation to geological structures or exothermal mineral processes. The DJI system is equipped with an optical camera for photogrammetric surveying and is a highly valuable tool in remote areas due to its lightweight and compact construction.Data acquired from both UAS is subsequently analysed in a Virtual Reality lab utilizing a 6m wide screen with active stereo functions. Photogrammetry data is first processed using the Aigsoft software package following a Structure for Motion (SfM) workflow where dense point cloud models and subsequently meshed and textured 3D surface models are produced. These models are then converted and transferred to the GeoVisionary software package that allows visualization of models in stereo 3D view. This allows digitizing geological structures such as foliation, fractures, and faults among others in an immersive 3D environment and provides an efficient tool complimentary to traditional field mapping. In particular, this makes it possible to capture and analyse data from hardly accessible and dangerous areas such as rock faces in open pits. Another complimentary method of data analysis comprises SCAT analysis of the meshed surfaces using the MOVE software package.
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| 3. |
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| 4. |
- Kampmann, Tobias Christoph, 1987-, et al.
(author)
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The benefits of organized networking and matchmaking for the development of 3D/4D geomodel visualization
- 2019
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In: Proceedings of the Visual3D conference 2019, 1–2 October 2019, Uppsala, Sweden. - Luleå, Sweden : Luleå University of Technology. ; , s. 43-43
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Conference paper (peer-reviewed)abstract
- While huge territory of the EU shows a very high exploration potential and many EU countries remain attractive to investors (e.g. Fraser Institute, 2015), a mere 4% of global exploration expenditure is currently invested within European countries. One tool to trigger a higher degree of investment in exploration and to secure the domestic supply of both main commodities and critical raw materials (CRM) is to enhance our three-dimensional geometric understanding of the Earth’s crust.For these reasons, EIT Raw Materials decided to fund the Visual3D network of infrastructure (NoI) for three years (2017–2019). Visual3D involves to-date 14 partner organisations from nine EU countries. The NoI aims to integrate expertise within exploration and 3D modelling from industry, academia and research institutes, with the ambition to increase the understanding of geological bodies in 3D and 4D through improved visualisation techniques. The network believes firmly that the integration of novel visualization technologies (e.g. virtual and augmented reality) into workflows of exploration, mining and geoscientific research will bring a much-needed innovation boost to the European raw materials sector and increase its competitiveness.During its first year, Visual3D has compiled the network expertise and infrastructure regarding visualization tools available at the partner facilities. An overview of this infrastructure, as well as projects conducted by network partners is available on the Visual3D homepage (www.visual3d.info). The network also managed to identify common issues in the field of geomodelling, the solutions to which may be facilitated by a pan-European network approach, such as data compatibility, communication of geomodels, as well as complexity and variety of software. Subsequent years have been dedicated to the conceptualization of possible projects in order to solve the issues name above, as well as matchmaking to find expert consortia for these projects.So far, four workshops including project partners and invited external stakeholders have been held. Networking and matchmaking during these workshops has resulted in successful project proposals in the EIT RawMaterials KAVA calls for educational (MireBooks), as well as upscaling projects (FARMIN). Both these projects are presented at the Visual3D conference 2019. Further project ideas have been discussed within Visual3D and will be developed further.The benefits of organized networking in novel research and developments fields, such as visualization of 3D/4D models for exploration and geosciences, has become apparent during the lifetime of the Visual3D network. The network partners would encourage pan-European funding institutions such as EIT RawMaterials to provide continuous funding to similar networking initiatives, especially in highly innovative and novel research fields. Well-organized communication between different stakeholders is the basis of technological innovation and has the potential to give the European raw materials sector the leading edge in this highly competitive global market.
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| 5. |
- Kampmann, Tobias Christoph, 1987-, et al.
(author)
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Visual3D : A European network of infrastructure with focus on 3D/4D geomodelling
- 2018
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Conference paper (peer-reviewed)abstract
- While the territory of the EU in many parts shows a very high exploration potential and many EU countries remain attractive to investors (e.g. Fraser Institute, 2015), a mere 4% of global exploration expenditure is currently invested within European countries. One tool to trigger a higher degree of investment in exploration and to secure the domestic supply of both main commodities and critical raw materials (CRM) is to enhance our three-dimensional geometric understanding of the Earth’s crust.For these reasons, EIT Raw Materials decided to fund a network of infrastructure (NoI) –Visual3D – for three years (2017–2019). Visual3D involves to-date 14 partner organisations from nine EU countries. The NoI aims to integrate expertise within exploration and 3D modelling from industry, academia and research institutes, with the ambition to increase the understanding of geological bodies in 3D and 4D through improved visualisation techniques.During its first year, Visual3D has worked to identify common issues in the field of geomodelling, the solutions to which may be facilitated by a Pan-European network approach:Data compatibility. The vast majority of European mining companies are currently working with 3D solutions for mine planning, resource estimation and production, utilizing a vast variety of expert programs (e.g. Leapfrog, Vulcan, Surpac, gOcad, MOVE). This leads to a wide range in character of 3D-models, as well as various types of data and file formats. Especially the combination of models on different scales, such as the incorporation of deposit scale models into regional-scale models, often necessitates simplifications and may lead to a loss of data. Therefore, a NoI that improves the interchangeability of models and furthermore enables full data integration will increase the usability of geomodels in exploration and research.Communication of geomodels. Commonly, specific expert software in order to make different data formats readable and communicate geomodels between collaborators, clients, stakeholders and decision makers. This limits the group of possible co-workers in a modelling project and the group of people that can utilize such models to the amount of available and often expensive licenses. A network of 3D-modelling users can substantially widen the possibilities to make geomodels accessible to a wider audience.Complexity and variety of CAM software. Software packages for computer-aided modelling (CAM) for geology and for industry standard mineral resource and reserve models are rather complex. Furthermore, there is a wide variety of available CAM software, each yielding individual functions, advantages and disadvantages. Changing a software or personnel within an organisation necessitates investment in additional training and causes downtimes. Implementing work flows for data interoperability may minimize expenditures on software and training for mining and exploration companies. Hence the NoI aims to work on solutions in order to optimize the generation, interpretation and application of geomodels, and improve the time and cost efficiency of these processes.Integration and improved outward communication of the available visualisation tools at the NoI partners will support better targeting of new mineral resources at depth, and eventually reduce environmental impacts and costs by enhancing the efficiency of exploration workflows. The distribution and possible commercialization of the NoI´s outcomes among stakeholders of the extractive industry will improve the competitiveness of European exploration and mining.
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| 8. |
- de Kock, Michiel Olivier, et al.
(author)
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U-Pb geochronology and paleomagnetism of the Westerberg sill, Kaapvaal Craton - Support for Vaalbara into the Paleoproterozoic
- 2014
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Conference paper (peer-reviewed)abstract
- Precise geochronology combined with paleomagnetism provides first-order information necessary for paleoreconstructions of crustal blocks and for revealing the history of supercontinent formation and break-up. These techniques are used here in an attempt to further constrain the apparent polar wander path of the Kaapvaal craton through the Neoarchean and Paleoproterozoic. A new baddeleyite U-Pb age of 2440.2 ± 5.9 Ma for the intracratonic Westerberg sill manifests a new event of mafic magmatism within the Kaapvaal Craton of southern Africa and falls in the center of a ca. 450 Ma gap in the paleomagnetic record, between 2.66 and 2.22 Ga. The Westerberg sill is coeval with the Woongarra sills on the Pilbara craton and intrudes into a remarkably similar sedimentary succession, hence supporting a coherent Kaapvaal-Pilbara block (i.e., Vaalbara) spanning the Archean-Proterozoic boundary interval. The coeval Westerberg-Woongarra igneous event may represent a large igneous province, here recognized for the first time on the Kaapvaal craton. The virtual geomagnetic pole obtained for the Kaapvaal craton for the Westerberg sill fits well into a large gap of the craton’s apparent polar wander path. Furthermore, combined with a coeval Pilbara pole, it allows for a reconstruction of Vaalbara that places Pilbara in relative close proximity and to the north of the Kaapvaal craton.
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| 9. |
- Fahlvik, Anton, et al.
(author)
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Hydrothermal alteration, lithogeochemical marker units and vectors towards mineralisation at the Svärdsjö Zn-Pb-Cu deposit, Bergslagen, Sweden
- 2022
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In: GFF. - : Taylor & Francis. - 1103-5897 .- 2000-0863. ; 144:3-4, s. 177-195
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Journal article (peer-reviewed)abstract
- The Svärdsjö Zn-Pb-Cu deposit is situated in the heavily mineralised Bergslagen lithotectonic unit of the Fennoscandian shield, south-central Sweden. Intense hydrothermal alteration followed by a strong overprint by deformation and metamorphism during the Svecokarelian orogeny complicate interpretation of the local geology. Integration of whole-rock lithogeochemical and petrographic methods has allowed the mainly dacitic volcanic host succession and effects of ore-related hydrothermal alteration to be characterised. Mineralisation is hosted by 2–15 m thick, commonly skarn-altered dolomitic marble interbeds. Zones of strong–intense hydrothermal chlorite-sericite alteration envelop the marble units, recording mass gains of Fe and Mg, as well as Na depletion. Minerals such as cordierite, anthophyllite and sillimanite formed in these rocks during regional metamorphism. Mineralisation via sub-seafloor replacement is suggested for the deposit based on alteration zoning and the irregular, stratabound, marble-hosted style of sulphide lenses. It is inferred that mineralisation formed via neutralisation of hot, acidic metalliferous fluids. Geochemically and lithologically distinct units adjacent to the mineralised zones can serve as marker units to aid further exploration in the area. Mass change calculations reveal that Fe and Mg enrichment, as well as Na depletion exhibit detectable changes extending up to 100 m from the mineralised lenses, providing exploration vectors.
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| 10. |
- Firsching, Markus, et al.
(author)
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REWO-SORT Sensor Fusion for Enhanced Ore Sorting: a Project Overview
- 2019
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In: Procemin GEOMET 2019. - : GECAMIN.
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Conference paper (peer-reviewed)abstract
- Among the numerous challenges recently confronting the mining industry is the need to process ore with successively lower grades due to the continuous depletion of high-grade deposits. This increases the consumption of energy and water and, thus, the operational costs at a mine site. Multimodal sorting represents a promising technique to achieve pre-concentration of valuable minerals already at an early stage in the metallurgical process.In the ERA-MIN2 project “Reduction of Energy and Water Consumption of Mining Operations by Fusion of Sorting Technologies LIBS and ME-XRT” (REWO-SORT), a fusion technology including laser-induced breakdown spectroscopy (LIBS) and multi energy X-ray transmission (ME-XRT) is being developed by a multidisciplinary expert consortium. The project aims at classifying crushed mineral particles on a conveyor belt with the aid of deep learning technologies. In addition, the operating conditions to work with high throughput while keeping a particle monolayer on the conveyor belt have been identified. The latter objective is addressed using discrete element method (DEM) simulations. Parameter calibrations were experimentally obtained using a copper sulfide ore from the Rafaela mining company (Chile). The combination of LIBS and ME-XRT is promising, as they complement each other regarding analytical and particle selection capabilities: LIBS can provide an elemental analysis of the sample surface, while ME-XRT produces volumetric data with lower accuracy. Both sensors will be combined to extrapolate accurate and representative volumetric data, thereby securing an optimal particle selection at high throughputs. First measurements and analyses of ore samples using LIBS and ME-XRT, as well as their correlation with the Cu concentration obtained by reference lab analysis will be presented and discussed. Preliminary DEM studies indicate the existence of a threshold of conveyor belt surface area covered with particles of around 85%. Above this value the particle monolayer cannot be maintained, imposing another restriction for the speed of sensor analysis.
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