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Bauer, T. & Andersson, J. B. .. (2023). Regional structural setting of late-orogenic IOCG mineralization along the northern Nautanen deformation zone, Norrbotten, Sweden. Ore Geology Reviews, 163, Article ID 105814.
Open this publication in new window or tab >>Regional structural setting of late-orogenic IOCG mineralization along the northern Nautanen deformation zone, Norrbotten, Sweden
2023 (English)In: Ore Geology Reviews, ISSN 0169-1368, E-ISSN 1872-7360, Vol. 163, article id 105814Article in journal (Refereed) Published
Abstract [en]

The northern Norrbotten ore province in Sweden is one of the most mineralized areas in Europe. Iron, gold and/or copper deposits occur as iron oxide-apatite-style mineralization (IOA, Kiruna-type) as well as iron oxide-copper–gold (IOCG) style. Regardless of mineralization style, most deposits appear to be spatially controlled by a set of crustal-scale Palaeoproterozoic shear zones which share similar structural characteristics and deformation histories.

Reappraisal of regional geological and geophysical data, coupled with structural mapping, suggests crustal-scale shear zones form continuous c. N-S-trending zones extending from the Skellefte district in the south into the northern Norrbotten ore province. One example from Norrbotten is a zone that extends SSW from Karesuando in the north towards Svappavaara. While this structure has traditionally been inferred to continue SW towards Arjeplog (i.e. the Karesuando – Arjeplog Deformation Zone; KADZ), we favour its deflection SSE into the Nautanen-Aitik trend, making it a continuous, IOCG-bearing, crustal-scale deformation zone. Similar shear zone geometries can be observed in analogous zones to the west. Most of these crustal scale structures record at least two time-separated deformation events of regional significance. IOA and IOCG deposits form in different tectonic environments, separated in time and overprinting each other.

Place, publisher, year, edition, pages
Elsevier, 2023
National Category
Earth and Related Environmental Sciences
Research subject
Ore Geology
Identifiers
urn:nbn:se:ltu:diva-104388 (URN)10.1016/j.oregeorev.2023.105814 (DOI)001139738400001 ()2-s2.0-85179624059 (Scopus ID)
Note

Validerad;2024;Nivå 2;2024-03-07 (signyg);

License full text: CC BY

Available from: 2024-02-27 Created: 2024-02-27 Last updated: 2024-03-26Bibliographically approved
Logan, L., Veress, E. C., Andersson, J. B. H., Martinsson, O. & Bauer, T. E. (2023). Structural framework and timing of the Pahtohavare Cu ± Au deposits, Kiruna mining district, Sweden. Solid Earth, 14(7), 763-784
Open this publication in new window or tab >>Structural framework and timing of the Pahtohavare Cu ± Au deposits, Kiruna mining district, Sweden
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2023 (English)In: Solid Earth, ISSN 1869-9510, E-ISSN 1869-9529, Vol. 14, no 7, p. 763-784Article in journal (Refereed) Published
Abstract [en]

As part of the larger mineral systems approach to Cu-bearing mineralization in northern Norrbotten, this study utilizes structural geology to set the classic Pahtohavare Cu ± Au deposits into an up-to-date tectonic framework. The Pahtohavare Cu ± Au deposits, situated only 5 km southwest of the Kiirunavaara world-class iron oxide–apatite (IOA) deposit, have a dubious timing, and their link to IOA formation is not constrained. The study area contains both epigenic Cu ± Au (Pahtohavare) and iron oxide–copper–gold (IOCG; Rakkurijärvi) mineral occurrences which are hosted in bedrock that has been folded and bound by two shear zones trending northeast to southwest and northwest to southeast to the east and southwest, respectively. Structural mapping and petrographic investigation of the area reveal a noncylindrical, SE-plunging anticline. The cleavage measurements mirror the fold geometry, which characterizes the fold as F2 associated with the late phase of the Svecokarelian orogeny. Porphyroclasts with pressure shadows, mylonitic fabrics, and foliation trails in porphyroblasts indicate S0/S1  is a tectonic fabric. The epigenetic Pahtohavare Cu ± Au mineralization sits in brittle–ductile structures that cross-cut an earlier foliation and the F2 fold, indicating that the timing of the deposits occurred syn- to post-F2 folding, at least ca. 80 Myr after the Kiirunavaara IOA formation. A 3D model and cross-sections of the Pahtohavare–Rakkurijärvi area and a new structural framework of the district are presented and used to suggest that the shear zones bounding the area are likely reactivated early structures that have played a critical role in ore formation in the Kiruna mining district.

Place, publisher, year, edition, pages
Copernicus Publications, 2023
National Category
Geology
Research subject
Ore Geology
Identifiers
urn:nbn:se:ltu:diva-100661 (URN)10.5194/se-14-763-2023 (DOI)001031584400001 ()2-s2.0-85170210557 (Scopus ID)
Projects
New Exploration Technologies – NEXT
Funder
EU, Horizon 2020, 776804
Note

Validerad;2023;Nivå 2;2023-08-21 (hanlid)

Available from: 2023-08-21 Created: 2023-08-21 Last updated: 2023-10-11Bibliographically approved
Logan, L., Andersson, J. B. H., Whitehouse, M. J., Martinsson, O. & Bauer, T. E. (2022). Energy Drive for the Kiruna Mining District Mineral System(s): Insights from U-Pb Zircon Geochronology. Minerals, 12(7), Article ID 875.
Open this publication in new window or tab >>Energy Drive for the Kiruna Mining District Mineral System(s): Insights from U-Pb Zircon Geochronology
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2022 (English)In: Minerals, E-ISSN 2075-163X, Vol. 12, no 7, article id 875Article in journal (Refereed) Published
Abstract [en]

The Kiruna mining district, Sweden, known for the type locality of Kiruna-type iron oxide-apatite (IOA) deposits, also hosts several Cu-mineralized deposits including iron oxide-copper-gold (IOCG), exhalative stratiform Cu-(Fe-Zn), and structurally controlled to stratabound Cu +/- Au. However the relationship between the IOA and Cu-systems has not been contextualized within the regional tectonic evolution. A broader mineral systems approach is taken to assess the timing of energy drive(s) within a regional tectonic framework by conducting U-Pb zircon geochronology on intrusions from areas where Cu-mineralization is spatially proximal. Results unanimously yield U-Pb ages from the early Svecokarelian orogeny (ca. 1923-1867 Ma including age uncertainties), except one sample from the Archean basement (2698 +/- 3 Ma), indicating that a distinct thermal drive from magmatic activity was prominent for the early orogenic phase. A weighted average Pb-207/Pb-206 age of 1877 +/- 10 Ma of an iron-oxide-enriched gabbroic pluton overlaps in age with the Kiirunavaara IOA deposit and is suggested as a candidate for contributing mafic signatures to the IOA ore. The results leave the role of a late energy drive (and subsequent late Cu-mineralization and/or remobilization) ambiguous, despite evidence showing a late regional magmatic-style hydrothermal alteration is present in the district.

Place, publisher, year, edition, pages
MDPI, 2022
Keywords
Kiruna, mineral system, U-Pb zircon geochronology, IOA, IOCG
National Category
Geophysics Geology
Research subject
Ore Geology
Identifiers
urn:nbn:se:ltu:diva-92436 (URN)10.3390/min12070875 (DOI)000833356600001 ()2-s2.0-85137380223 (Scopus ID)
Funder
EU, Horizon 2020, 776804Swedish Research Council, 2017-00671
Note

Validerad;2022;Nivå 2;2022-08-11 (hanlid)

Available from: 2022-08-11 Created: 2022-08-11 Last updated: 2024-01-17Bibliographically approved
Andersson, J. B. .., Logan, L., Martinsson, O., Chew, D., Kooijman, E., Kielman-Schmitt, M., . . . Bauer, T. E. (2022). U-Pb zircon-titanite-apatite age constraints on basin development and basin inversion in the Kiruna mining district, Sweden. Precambrian Research, 372, Article ID 106613.
Open this publication in new window or tab >>U-Pb zircon-titanite-apatite age constraints on basin development and basin inversion in the Kiruna mining district, Sweden
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2022 (English)In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 372, article id 106613Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Geochronology, Kiruna, IOA, basin development, basin inversion
National Category
Geology
Research subject
Ore Geology; Centre - Centre for Advanced Mining & Metallurgy (CAMM)
Identifiers
urn:nbn:se:ltu:diva-87738 (URN)10.1016/j.precamres.2022.106613 (DOI)000807894300001 ()2-s2.0-85125532558 (Scopus ID)
Funder
EU, Horizon 2020, 776804
Note

Validerad;2022;Nivå 2;2022-03-31 (hanlid);

Funder: Centre of Advanced Mining and Metallurgy (CAMM) (2450-2009); Science Foundation Ireland (SFI) (13/RC/2092 and 13/RC/2092_P2)

Available from: 2021-11-03 Created: 2021-11-03 Last updated: 2023-09-05Bibliographically approved
Andersson, J. (2021). Paleoproterozoic deformation in the Kiruna‑Gällivare area in northern Norrbotten, Sweden: Setting, character, age, and control of iron oxide-apatite deposits. (Doctoral dissertation). Luleå: Luleå University of Technology
Open this publication in new window or tab >>Paleoproterozoic deformation in the Kiruna‑Gällivare area in northern Norrbotten, Sweden: Setting, character, age, and control of iron oxide-apatite deposits
2021 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis covers the structural evolution of the Kiruna‑Gällivare area in the northern Norrbotten ore province, Sweden. The study area hosts several economically significant iron oxide-apatite (IOA) deposits and includes the type locality for this ore type. Despite the abundant work on the genesis of IOA-systems, their structural setting and control is poorly constrained. This highlights the need for multi-scale structural studies that can help to unravel structural controls on the genesis and overprinting deformation histories. Four IOA-hosting key study areas were under investigation covering multi-scale structural controls from regional to deposit scale. Extensive geological mapping focused on structures, stratigraphy, and hydrothermal alteration, combined with multi-scale structural analysis and U-Pb geochronology was conducted. Results are synthesized in a time-constrained tectonothermal model for IOA deposits and host rocks of the Kiruna‑Gällivare area.

The results indicate that the IOA deposits in Norrbotten formed in an overall extensional regime coeval with basin development in a backarc setting. The onset of basin development is indicated by a U-Pb age in zircon from a volcanic intercalation in a stratigraphically basal alluvial conglomerate of the ore-bearing sequence. A titanite age indicates that an ore-proximal cataclastic fault has syn-volcanic origin and formed coeval with basin development and ore formation. A similar origin is postulated for ore-proximal biotite-bearing structures at the Malmberget IOA deposit. In comparison with Kiruna, the Malmberget area experienced higher metamorphic conditions and records a more complex deformation history. 

Following backarc extension, subsequent crustal shortening resulted in basin inversion and re-activation of structures. Crustal scale, reverse shear zones developed in favourable lithologies and inferred pre-existing structures during D1. The timing of D1 crustal shortening coincides with peak metamorphism (M1) and is bracketed by crosscutting relationships. In contrast, the timing of an overprinting D2 crustal shortening is directly constrained by U-Pb geochronology in titanite indicating an age of approx. 1.8 Ga during an event tentatively interpreted to have lasted up to 20 m.y. This time span is coeval with the exhumation of the Kiruna mining district as recorded by an U‑Pb reset age in apatite in association to an IOA deposit. The D2 deformation is characterized by reactivation of older structures and responsible for juxtaposition of blocks from different crustal levels and tectonic exhumation into upper crustal domains. Transposition of fabrics and ore bodies into re-activated listric faults during basin inversion explains sub-parallel relationships between the ore-proximal structures, bedding, and stratiform/stratabound orebodies.

Sodic-calcic + Fe ± Cl alteration is widespread and generally sits in early structural positions and interpreted as pre‑ to syn‑D1. However, U-Pb titanite results indicate that sodic-calcic alteration was developed also during the younger D2 event and shows that the alteration style is temporally and spatially widely distributed. Commonly, the alteration styles associated with D2 deformation are potassic in character and associated to Fe- and Cu-sulphide minerals. These potassic alteration assemblages sit in structurally late positions, often brittle in character. Sulphides were remobilized into D2-structures and the entrapment style is mainly controlled by rock competency.

A least two additional overprinting deformation phases are identified (D3 and D4). Clockwise rotation of the overall crustal shortening direction resulted in a gentle refolding of the inverted basin and influences the shape of some IOA deposits in the Kiruna mining district. Dominant joint structures at the Malmberget IOA deposit are indicated as relatively early features and their development is controlled by pre-existing foliation and crosscut by hydrothermally altered structures, that may be coeval with hydraulic fracturing in the Kiruna mining district that crosscut all other fabrics.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2021. p. 37
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
Keywords
Kiruna, Gällivare, structural geology, Paleoproterozoic, deformation
National Category
Geology
Research subject
Ore Geology
Identifiers
urn:nbn:se:ltu:diva-87741 (URN)978-91-7790-973-6 (ISBN)978-91-7790-974-3 (ISBN)
Public defence
2021-12-17, E632, Luleå, 08:00 (English)
Opponent
Supervisors
Available from: 2021-11-04 Created: 2021-11-03 Last updated: 2023-09-05Bibliographically approved
Andersson, J. B. .., Bauer, T. & Martinsson, O. (2021). Structural Evolution of the Central Kiruna Area, Northern Norrbotten, Sweden: Implications on the Geologic Setting Generating Iron Oxide-Apatite and Epigenetic Iron and Copper Sulfides. Economic geology and the bulletin of the Society of Economic Geologists, 116(8), 1981-2009
Open this publication in new window or tab >>Structural Evolution of the Central Kiruna Area, Northern Norrbotten, Sweden: Implications on the Geologic Setting Generating Iron Oxide-Apatite and Epigenetic Iron and Copper Sulfides
2021 (English)In: Economic geology and the bulletin of the Society of Economic Geologists, ISSN 0361-0128, E-ISSN 1554-0774, Vol. 116, no 8, p. 1981-2009Article in journal (Refereed) Published
Abstract [en]

To guide future exploration, this predominantly field based study has investigated the structural evolution of the central Kiruna area, the type locality for iron oxide-apatite deposits that stands for a significant amount of the European iron ore production. Using a combination of geologic mapping focusing on structures and stratigraphy, petrography with focus on microstructures, X-ray computed tomography imaging of sulfide-structure relationships, and structural 2D-forward modeling, a structural framework is provided including spatial-temporal relationships between iron oxide-apatite emplacement, subeconomic Fe and Cu sulfide mineralization, and deformation. These relationships are important to constrain as a guidance for exploration in iron oxide-apatite and iron oxide copper-gold prospective terrains and may help to understand the genesis of these deposit types. Results suggest that the iron oxide-apatite deposits were emplaced in an intracontinental back-arc basin, and they formed precrustal shortening under shallow crustal conditions. Subsequent east-west crustal shortening under greenschist facies metamorphism inverted the basin along steep to moderately steep E-dipping structures, often subparallel with bedding and lithological contacts, with reverse, oblique to dip-slip, east-block-up sense of shears. Fe and Cu sulfides associated with Fe oxides are hosted by structures formed during the basin inversion and are spatially related to the iron oxide-apatite deposits but formed in fundamentally different structural settings and are separated in time. The inverted basin was gently refolded and later affected by hydraulic fracturing, which represent the last recorded deformation-hydrothermal events affecting the crustal architecture of central Kiruna.

Place, publisher, year, edition, pages
Society of Economic Geologists, 2021
National Category
Geology
Research subject
Ore Geology
Identifiers
urn:nbn:se:ltu:diva-87685 (URN)10.5382/econgeo.4844 (DOI)000707200500001 ()2-s2.0-85122448953 (Scopus ID)
Note

Validerad;2021;Nivå 2;2021-10-29 (beamah);

Forskningsfinansiär: Centre of Advanced Mining and Metallurgy

Available from: 2021-10-29 Created: 2021-10-29 Last updated: 2024-03-23Bibliographically approved
Andersson, J., Bauer, T. & Lynch, E. P. (2020). Evolution of structures and hydrothermal alteration in a Palaeoproterozoic supracrustal belt: Constraining paired deformation–fluid flow events in an Fe and Cu–Au prospective terrain in northern Sweden. Solid Earth, 11(2), 547-578
Open this publication in new window or tab >>Evolution of structures and hydrothermal alteration in a Palaeoproterozoic supracrustal belt: Constraining paired deformation–fluid flow events in an Fe and Cu–Au prospective terrain in northern Sweden
2020 (English)In: Solid Earth, ISSN 1869-9510, E-ISSN 1869-9529, Vol. 11, no 2, p. 547-578Article in journal (Refereed) Published
Abstract [en]

An approximately 90 km long Palaeoproterozoic supracrustal belt in the northwestern Norrbotten ore province (northernmost Sweden) was investigated to characterize its structural components, assess hydrothermal alteration–structural geology correlations, and constrain a paired deformation–fluid flow evolution for the belt. New geological mapping of five key areas (Eustiljåkk, Ekströmsberg, Tjårrojåkka, Kaitum West, and Fjällåsen–Allavaara) indicates two major compressional events (D1 and D2) have affected the belt, with each associated with hydrothermal alteration types typical for iron oxide–apatite and iron oxide Cu–Au systems in the region. Early D1 generated a regionally distributed, penetrative S1 foliation and oblique reverse shear zones that show a southwest-block-up sense of shear that formed in response to NE–SW crustal shortening. Peak regional metamorphism at epidote–amphibolite facies broadly overlaps with this D1 event. Based on overprinting relationships, D1 is associated with regional scapolite ± albite, magnetite + amphibole, and late calcite alteration of mafic rock types. These hydrothermal mineral associations linked to D1 structures may form part of a regionally pervasive evolving fluid flow event but are separated in this study by crosscutting relationships.

During D2 deformation, folding of S0–S1 structures generated F2 folds with steeply plunging fold axes in low-strain areas. NNW-trending D1 shear zones experienced reverse dip-slip reactivation and strike-slip-dominated movements along steep, E–W-trending D2 shear zones, producing brittle-plastic structures. Hydrothermal alteration linked to D2 structures is a predominantly potassic–ferroan association comprising K-feldspar ± epidote ± quartz ± biotite ± magnetite ± sericite ± sulfides. Locally, syn- or post-tectonic calcite is the main alteration mineral in D2 shear zones that intersect mafic rocks. Our results highlight the importance of combining structural geology with the study of hydrothermal alterations at regional to belt scales to understand the temporal–spatial relationship between mineralized systems. Based on the mapping results and microstructural investigations as well as a review of earlier tectonic models presented for adjacent areas, we suggest a new structural model for this part of the northern Fennoscandian Shield. The new model emphasizes the importance of reactivation of early structures, and the model harmonizes with tectonic models presented by earlier workers based mainly on petrology of the northern Norrbotten area.

Place, publisher, year, edition, pages
Copernicus publications, 2020
National Category
Geology
Research subject
Ore Geology
Identifiers
urn:nbn:se:ltu:diva-78783 (URN)10.5194/se-11-547-2020 (DOI)000527805400001 ()2-s2.0-85083756752 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-05-05 (johcin)

Available from: 2020-05-05 Created: 2020-05-05 Last updated: 2023-09-04Bibliographically approved
Sarlus, Z., Andersson, U. B., Martinsson, O., Bauer, T. E., Wanhainen, C., Andersson, J. B. .. & Whitehouse, M. J. (2020). Timing and origin of the host rocks to the Malmberget iron oxide-apatite deposit, Sweden. Precambrian Research, 342, Article ID 105652.
Open this publication in new window or tab >>Timing and origin of the host rocks to the Malmberget iron oxide-apatite deposit, Sweden
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2020 (English)In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 342, article id 105652Article in journal (Refereed) Published
Abstract [en]

The northern Norrbotten region in Sweden hosts abundant iron-oxide apatite (IOA) deposits including Kiirunavaara, the type locality for Kiruna-type deposits, and Malmberget. Felsic and intermediate metavolcanic rocks hosting the Malmberget IOA deposit contain oscillatory zoned zircon which yield magmatic U-Pb SIMS ages of 1885±6 Ma and 1881±6 Ma, respectively. Metamorphic rims on zircon from these rocks yield 1797±7 Ma and 1775±6 Ma, respectively, and record the age of the latest Svecofennian regional metamorphic event in the Gällivare area, tentatively interpreted as regional contact metamorphism. Two granite dikes that cut the ore yield U-Pb zircon emplacement ages of 1790±6 Ma and 1791±7 Ma, respectively, overlapping with the metamorphic overgrowths, and set a lower age limit for ore formation in the Malmberget IOA deposit. Rocks hosting the Malmberget IOA deposit have an alkalic to alkali-calcic affinity with a geochemical signature that favors a continental-arc, transitional to extensional setting. These rocks are suggested to have been generated in a back-arc region, in response to subduction beneath the craton margin retreating to the SW or W. The obtained ages and geochemical signatures of these rocks coincide well with the regionally defined Kiirunavaara group rocks, hosting several other IOA deposits in northern Sweden.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
U-Pb SIMS geochronology, northern Sweden, Svecofennian, IOA deposit
National Category
Geology
Research subject
Ore Geology
Identifiers
urn:nbn:se:ltu:diva-77874 (URN)10.1016/j.precamres.2020.105652 (DOI)000528208200001 ()2-s2.0-85080036882 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-04-06 (alebob)

Available from: 2020-02-26 Created: 2020-02-26 Last updated: 2023-09-05Bibliographically approved
Bauer, T. E., Andersson, J. B. .. & Kampmann, T. C. (2019). Analysis of data from Unmanned Aerial Systems (UAS) in a Virtual Reality environment. In: Tobias C. Kampmann (Ed.), Proceedings of the Visual3D conference 2019, 1–2 October 2019, Uppsala, Sweden: Visualization of 3D/4D models in geosciences, exploration and mining: . Paper presented at Visual3D conference 2019, Uppsala, Sweden, October 1–2, 2019 (pp. 19-19). Luleå University of Technology
Open this publication in new window or tab >>Analysis of data from Unmanned Aerial Systems (UAS) in a Virtual Reality environment
2019 (English)In: Proceedings of the Visual3D conference 2019, 1–2 October 2019, Uppsala, Sweden: Visualization of 3D/4D models in geosciences, exploration and mining / [ed] Tobias C. Kampmann, Luleå University of Technology, 2019, p. 19-19Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

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.

Place, publisher, year, edition, pages
Luleå University of Technology, 2019
National Category
Geosciences, Multidisciplinary
Research subject
Ore Geology
Identifiers
urn:nbn:se:ltu:diva-76446 (URN)
Conference
Visual3D conference 2019, Uppsala, Sweden, October 1–2, 2019
Note

ISBN för värdpublikation: 978-91-7790-474-8

Available from: 2019-10-18 Created: 2019-10-18 Last updated: 2023-09-04Bibliographically approved
Sarlus, Z., Martinsson, O., Bauer, T., Wanhainen, C., Andersson, J. & Nordin, R. (2019). Character and tectonic setting of plutonic rocks in the Gällivare area, northern Norrbotten, Sweden. GFF, 141(1), 1-20
Open this publication in new window or tab >>Character and tectonic setting of plutonic rocks in the Gällivare area, northern Norrbotten, Sweden
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2019 (English)In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 141, no 1, p. 1-20Article in journal (Refereed) Published
Abstract [en]

Petrographical and lithogeochemical investigations in combination with mapping in the Gällivare area, northern Norrbotten, Sweden, have led to the identification of several igneous intrusive rock types. These include: (1) ultramafic-mafic complexes, (2) mafic-intermediate rocks, (3) dolerites and (4) felsic plutons. The ultramafic-mafic rocks include the ca. 1.88 Ga Dundret complex and ca. 1.80 Ga Vassaravaara complex. The Dundret complex has tholeiitic to calc-alkaline affinity, shows a primitive mineral content and was formed in an extensional tectonic setting. The Vassaravaara complex has a similar chemical signature as the Dundret complex. The mafic-intermediate plutons vary in composition from gabbro to diorite. The chemical signature of the dioritic rocks indicate formation in a volcanic arc setting. Dolerites occur as solitary dikes and have calc-alkaline affinity. The felsic plutons include granite and syenite of ca. 1.88, 1.80 and 1.78 Ga age. The felsic plutons have calc-alkaline to shoshonitic affinity and mostly show a metaluminous I-type character. Results indicate subduction at 1.90 Ga resulting in a volcanic arc system, and including extensional events generating back-arc environments leading to mafic, intermediate and felsic magmatism in the Gällivare area. Subduction at 1.80 Ga is suggested to have caused a similar process generating mafic and felsic magmatic rocks in the same area. A subsequent collision event finally generated 1.78 Ga granitic rocks.

Place, publisher, year, edition, pages
Taylor & Francis, 2019
Keywords
Gällivare area, mafic layered intrusions, petrography, lithogeochemistry, back-arc environment
National Category
Geology
Research subject
Ore Geology
Identifiers
urn:nbn:se:ltu:diva-69190 (URN)10.1080/11035897.2018.1526209 (DOI)000467182600001 ()2-s2.0-85057552346 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-06-18 (johcin)

Available from: 2018-06-08 Created: 2018-06-08 Last updated: 2023-09-05Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-8682-8180

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