Change search
Link to record
Permanent link

Direct link
BETA
Publications (10 of 92) Show all publications
Billström, K., Evins, P., Martinsson, O., Jeon, H. & Weihed, P. (2019). Conflicting zircon vs. titanite U-Pb age systematics and the deposition of the host volcanic sequence to Kiruna-type and IOCG deposits in northern Sweden, Fennoscandian shield. Precambrian Research, 321, 123-133
Open this publication in new window or tab >>Conflicting zircon vs. titanite U-Pb age systematics and the deposition of the host volcanic sequence to Kiruna-type and IOCG deposits in northern Sweden, Fennoscandian shield
Show others...
2019 (English)In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 321, p. 123-133Article in journal (Refereed) Published
Abstract [en]

The Northern Norrbotten region, and in particular the Kiruna area, hosts a number of large apatite iron oxide deposits (e.g. the huge Kiirunavaara ore) of significant economic importance. Age data from rock lithologies hosting these ores, represented by metamorphosed rocks of the Porphyrite and Kiirunavaara Groups, are complex to interpret. This is illustrated by (LA-ICP-MS) data for titanite, and to some extent for rutile, which scatter considerably yielding ages within a span from ca. 2.1 Ga to 1.7 Ga. These analysed hydrothermal minerals, characterized by complex BSE images revealing darker and brighter zones, are located in ore zones and associated with e.g. strong scapolitisation, albitisation and actinolitisation. Previous (TIMS) zircon ages of host rocks, on the other hand, define a more narrower age interval between ca. 1900 and 1870 Ma, and this is supported by new U-Pb zircon results presented here. Furthermore, one coherent set of SIMS data for titanite from the Luossavaara ore favour that crystallization took place at ca 1.88 Ga, although laser ICP data from the same locality are much more complex. An implication arising from published pre-1.9 Ga laser ablation ages for titanites is that the emplacement of host rocks started already at around 2.1 Ga. As the depositional time of these rocks is crucial for the understanding of the overall crustal formation in northern Norrbotten, additional rocks were selected for age dating. New zircon age data (LA-ICP-MS and SIMS) give support to a scenario where host rocks to ores started to develop at around 1900 Ma and this calls for a re-evaluation of published LA-ICP-MS data of hydrothermal mineral phases.

Here, we present four models that aim to explain how pre-1.9 Ga titanite ages, believed to have a questionable geological significance, may develop. The principal idea is that ≤2.1 Ga alteration events were not responsible for the crystallization of the hydrothermal minerals, instead it is believed that apparent old age domains carry excess radiogenic lead due to the effect of ≤1.9 Ga hydrothermal processes. Currently, the interpretation of U-Pb isotope data in the study area remains enigmatic, and further radiometric analyses are required.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
U-Pb age, Iron ore, Norrbotten, Sweden, Zircon, Titanite
National Category
Geology
Research subject
Ore Geology
Identifiers
urn:nbn:se:ltu:diva-72749 (URN)10.1016/j.precamres.2018.12.003 (DOI)000457657500008 ()2-s2.0-85058180697 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-01-31 (johcin)

Available from: 2019-01-31 Created: 2019-01-31 Last updated: 2019-03-08Bibliographically approved
Hällström, L., Alakangas, L. & Martinsson, O. (2018). Geochemical characterization of W, Cu and F skarn tailings at Yxsjöberg, Sweden. Journal of Geochemical Exploration, 194, 266-279
Open this publication in new window or tab >>Geochemical characterization of W, Cu and F skarn tailings at Yxsjöberg, Sweden
2018 (English)In: Journal of Geochemical Exploration, ISSN 0375-6742, E-ISSN 1879-1689, Vol. 194, p. 266-279Article in journal (Refereed) Published
Abstract [en]

Little attention has been paid to tailings from skarn ore deposits and their environmental impact, even though they can contain elevated concentrations of elements of potential concern together with sulfides and fluorite. Historical skarn tailings at Yxsjöberg, Sweden, containing e.g. Be, Bi, Cu, F, Sn, S, W, and Zn were geochemically characterized as a first step to evaluate the environmental impact and the potential to re-mine the tailings. The tailings were deposited between 1897 and 1963 in the Smaltjärnen Repository without dams or a complete cover, and have been in contact with the atmosphere for >30 years. Four vertical cores throughout the tailings were taken and divided into 134 subsamples, which were analyzed for total concentrations and paste pH. Selected samples from different depths were mineralogically characterized using optical microscopy, scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), Raman vibrational spectroscopy, and X-ray diffraction (XRD). Minerals, hand-picked from drilled rock cores, were analyzed for the element content, and a modified Element to Mineral Conversion (EMC) that pinpoints the quantitative distribution of elements between the minerals in the tailings was carried out. The average concentrations of Be, Bi, Cu, Sn, Zn, W, F and S in the tailings were 284, 495, 946, 559, 301, and 960 ppm, and 1.9 and 1.2 wt%, respectively. The tailings has reached a late stage development due to pyrrhotite oxidation resulting in low pH (<4) in the uppermost tailings, and formations of secondary minerals such as gypsum, hydrous ferric oxides (HFO) and orthogonal calcite. Secondary pyrite and magnetite, formed from monoclinic pyrrhotite was detected, and different weathering rates of secondary pyrite, hexagonal and monoclinic pyrrhotite was indicated, with secondary pyrite as the most stable and monoclinic pyrrhotite as the least. The rare and easily-weathered mineral danalite (Fe4Be3(SiO4)3S) was found in the drilled rock cores and by XRD in the tailings. However, the mineral could not be found by optical microscopy or SEM-EDS. This suggests that the mineral has been weathered to a great extent, which poses a high risk of releasing elements of potential concern to the groundwater since danalite contains approximately 40% of the total Be and Zn concentrations in the tailings. Fluorine was mainly found in fluorite, Cu in chalcopyrite, and Bi in bismuthinite; which all showed signs of weathering in acidic condition in the uppermost part, subsequent with decreased concentrations, followed by accumulation peaks deeper down in the tailings correlated with Al. Tungsten was mainly found in scheelite; most grains were unweathered, but a few grains had altered rims or HFO on the mineral surfaces. Tin was mainly found in ferrohornblende, hedenbergite and grossular. Beryllium, Cu, F, and Zn has high potential to be released to the surrounding environment from the Smaltjärnen Repository, while W, Bi and Sn are relatively stable in the tailings. Most of the scheelite is intact and re-mining could, therefore, be a suitable remediation method that would both reduce the environmental impact and simultaneously support the supply of critical raw materials in the EU.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Geology Geochemistry
Research subject
Applied Geochemistry; Ore Geology
Identifiers
urn:nbn:se:ltu:diva-70827 (URN)10.1016/j.gexplo.2018.09.001 (DOI)000447940000021 ()2-s2.0-85053199965 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-09-21 (svasva)

Available from: 2018-09-11 Created: 2018-09-11 Last updated: 2018-11-15Bibliographically approved
Hällström, L., Alakangas, L. & Martinsson, O. (2018). Metal Release from Acidic and Near-Neutral pH-Conditions in Historical W, Cu and F Skarn Tailings at Yxsjöberg, Sweden. In: Wolkersdorfer, Ch.; Sartz, L.; Weber, A.; Burgess, J.; Tremblay, G. (Ed.), 11th ICARD | IMWA | WISA MWD 2018 Conference: Risk to Opportunity. Paper presented at 11th ICARD IMWA MWD Conference “Risk to Opportunity” (ICARD 2018), September 10-14, 2018, Pretoria, South Africa. (pp. 351-356). , 1
Open this publication in new window or tab >>Metal Release from Acidic and Near-Neutral pH-Conditions in Historical W, Cu and F Skarn Tailings at Yxsjöberg, Sweden
2018 (English)In: 11th ICARD | IMWA | WISA MWD 2018 Conference: Risk to Opportunity / [ed] Wolkersdorfer, Ch.; Sartz, L.; Weber, A.; Burgess, J.; Tremblay, G., 2018, Vol. 1, p. 351-356Conference paper, Published paper (Refereed)
Abstract [en]

Weathering products stored in the pore water and/or as easily soluble salts in historical skarn tailings containing Be, Bi, Cu, W, and Zn, were released in water soluble fraction in the upper-most acidic tailings, at the visual oxidation front (1.5m), and/or below 2.5m (pH>7). Thus, there is a risk that these metals can pollute receiving waters by neutral mine drainage. Re-mining the tailings could be a suitable remediation method that would both reduce the environmental impact and simultaneously support the supply of metals.

National Category
Geochemistry
Research subject
Applied Geochemistry; Ore Geology
Identifiers
urn:nbn:se:ltu:diva-71880 (URN)9780620806503 (ISBN)
Conference
11th ICARD IMWA MWD Conference “Risk to Opportunity” (ICARD 2018), September 10-14, 2018, Pretoria, South Africa.
Available from: 2018-12-04 Created: 2018-12-04 Last updated: 2019-01-15Bibliographically approved
Salifu, M., Aiglsperger, T., Hällström, L., Martinsson, O., Billström, K., Ingri, J., . . . Alakangas, L. (2018). Strontium (87Sr/86Sr) isotopes: A tracer for geochemical processes in mineralogically-complex mine wastes. Applied Geochemistry, 99, 42-54
Open this publication in new window or tab >>Strontium (87Sr/86Sr) isotopes: A tracer for geochemical processes in mineralogically-complex mine wastes
Show others...
2018 (English)In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 99, p. 42-54Article in journal (Refereed) Published
Abstract [en]

Interpretation of geochemical data based primarily on elemental concentrations often lead to ambiguous results due to multiple potential sources including mineral weathering, atmospheric input, biological cycling, mineral precipitation and exchange processes. The 87Sr/86Sr ratio is however not fractionated by these processes. In this study, Sr isotope (87Sr/86Sr) ratios have been coupled with chemical data of Sr and Rb-bearing minerals, tailings and leachates (water-soluble) to gain insight into the geochemical processes occurring within the Yxsjöberg Cu-W mine tailings, Sweden. The tailings have been exposed to oxidizing conditions resulting in three geochemical zones namely (i) oxidized, (ii) transition and (iii) unoxidized zones. Leachates from the oxidized zone are acidic (pH = 3.6–4.5) and contain elevated concentrations of metals (e.g. Fe, Cu and Zn) and SO4. The low pH has also led to subsequent weathering of most silicates, releasing Al, Ca, Mg and Na into solution. The 87Sr/86Sr ratio in the tailings ranges from 0.84787 to 1.26640 in the oxidized zone, 0.92660–1.06788 in the transition zone, whilst the unoxidized zone has values between 0.76452 and 1.05169. For the leachates, the 87Sr/86Sr ratio ranges from 2.44479 to 5.87552 in the oxidized zone, 1.37404–1.68844 in the transition zone and 1.03697–2.16340 in the unoxidized zone. Mixing (between mineral weathering and atmospheric sources) was identified as the major process regulating the Sr composition of the tailings and leachates. The highly radiogenic signatures of the leachates in the oxidized zone suggests weathering of biotite, K-feldspar and muscovite. Despite the very radiogenic signatures in the oxidized zone, increments in Ca/K ratios, Be, Ce, Tl, Al, Fe and SO4 concentrations in the water-soluble phase were recorded in its lower parts which suggests the dissolution of amphibole, pyroxene, plagioclase, fluorite, gypsum, Al and Fe –(oxy) hydroxides as well as cation exchange by clay minerals. Presence of clay minerals has led to the partial retainment of radiogenic 87Sr/86Sr resulting in increased 87Sr/86Sr in the solid tailings material at these depths. The 87Sr/86Sr ratios of the water-soluble phase in the transition zone is similar to that of helvine and could indicate its dissolution. In the upper part of the oxidized zone, the 87Sr/86Sr ratios and trends of Be, Ca, SO4, Tl and Zn in the water-soluble phase suggest the dissolution of gypsum which precipitated from a leachate with the isotopic signature of helvine. In the lower part of the unoxidized zone, elevated concentrations of W were recorded suggesting scheelite weathering. But the 87Sr/86Sr ratios are higher than that expected from dissolution of scheelite and indicates additional processes. Possible sources include biotite weathering and groundwater. This study reveals that when interpreting geochemical processes in mine waste environments, 87Sr/86Sr should be considered in addition to chemical constituents, as this isotopic tracer offers better insights into discriminating between different solute sources.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Strontium isotopes, Silicate weathering, Yxsjöberg, Skarn mine tailings, Water-soluble
National Category
Geochemistry Geology
Research subject
Applied Geochemistry; Ore Geology
Identifiers
urn:nbn:se:ltu:diva-71501 (URN)10.1016/j.apgeochem.2018.10.022 (DOI)000451029300005 ()2-s2.0-85055999912 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-11-07 (johcin)

Available from: 2018-11-07 Created: 2018-11-07 Last updated: 2019-01-10Bibliographically approved
Sarlus, Z., Andersson, U. B., Bauer, T. E., Wanhainen, C., Martinsson, O., Nordin, R. & Andersson, J. B. .. (2018). Timing of plutonism in the Gällivare area: mplications for Proterozoic crustal development in the northern Norrbotten ore district, Sweden. Geological Magazine, 155(6), 1351-1376
Open this publication in new window or tab >>Timing of plutonism in the Gällivare area: mplications for Proterozoic crustal development in the northern Norrbotten ore district, Sweden
Show others...
2018 (English)In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 155, no 6, p. 1351-1376Article in journal (Refereed) Published
Abstract [en]

Zircon ion probe (secondary-ion mass spectrometry or SIMS) data from a set of intrusive rocks emplaced in the vicinity of major ore bodies, as well as from large igneous intrusions in the Gällivare area, gave the following results: (1) the Dundret ultramafic–mafic layered complex (1883±5 Ma), the Aitik granite (1883±5 Ma), the Nautanen diorite (1870±12 Ma), the Vassaravaara ultramafic–mafic layered complex (1798±4 Ma), the Aitik dolerite (1813±9 Ma), the Bergmästergruvan and Sikträsk syenites (1795±4 Ma and 1801±3 Ma, respectively) and the Naalojärvi granite (1782±5 Ma). These data broadly fall within the ranges 1.89–1.87 Ga (early Svecofennian) and 1.80–1.78 Ga (late Svecofennian), but geochronologically allow further subdivision into pulses at 1885–1880, 1875–1870, 1800 and 1780 Ma. During these events, large layered ultramafic–mafic and felsic plutonic rocks were generated with distinct overlap in time suggesting coeval felsic–mafic magmatism. Results also indicate the presence of inherited c. 1.87 Ga zircon crystals in the plutonic rocks at 1.78 Ga, supporting reworking of the previous crust. These data indicate the importance of mantle-derived mafic underplating in the process of crustal magma generation in the region. The c. 1.88 Ga event that generated ultramafic–mafic layered complexes is tentatively suggested to have played an important role in the formation of the Aitik Cu–Au porphyry system. The later event at c. 1.80 Ga, generating voluminous mafic–felsic units, is suggested to be coupled to the regional iron-oxide-copper-gold (IOCG) overprint.

Place, publisher, year, edition, pages
Cambridge University Press, 2018
National Category
Geology
Research subject
Ore Geology
Identifiers
urn:nbn:se:ltu:diva-63390 (URN)10.1017/S0016756817000280 (DOI)000439690800008 ()2-s2.0-85018356169 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-07-26 (inah)

Available from: 2017-05-17 Created: 2017-05-17 Last updated: 2018-08-15Bibliographically approved
Warlo, M., Martinsson, O., Wanhainen, C., Karlsson, P. & Höglund, S. (2017). Mineralisation paragenesis of the Liikavaara Cu-(W-Au) deposit, northern Sweden. In: Mercier Langevin, P; Dube, B; Bardoux, M; Ross, PS; Dion, C (Ed.), Mineral Resources to Discover: . Paper presented at 14th SGA Biennial Meeting on Mineral Resources to Discover, Quebec City, Canada, AUG 20-23, 2017 (pp. 971-974). Society for Geology Applied to Mineral Deposits
Open this publication in new window or tab >>Mineralisation paragenesis of the Liikavaara Cu-(W-Au) deposit, northern Sweden
Show others...
2017 (English)In: Mineral Resources to Discover / [ed] Mercier Langevin, P; Dube, B; Bardoux, M; Ross, PS; Dion, C, Society for Geology Applied to Mineral Deposits , 2017, p. 971-974Conference paper, Published paper (Refereed)
Abstract [en]

The Liikavaara Cu-(W-Au) deposit is located in the Gallivare ore district in northern Sweden, a few kilometres east of the renowned Aitik Cu-(Au) deposit. Its enrichment in Critical Raw Materials and its scheduled production for the near future make the Liikavaara deposit ideal as the subject of a case study on improved ore characterisation using various micro-analytical techniques. Here we present a general overview of the mineralogy in Liikavaara to provide a base for future micro-analytical studies. The deposit lies within Palaeoproterozoic volcanosedimentary rocks of andesitic composition. A unit of biotite schist hosts the ore. Mineralisation in Liikavaara is mainly controlled by quartz-(calcite)-(tourmaline) veins. Aplitic dykes and calcite veinlets also cut the deposit. Ore minerals are chalcopyrite, pyrrhotite, pyrite, sphalerite, galena, and molybdenite. Non-sulfide sources include scheelite and minor magnetite. The deposit is affected by alteration such as sericitisation, calcification, tourmalinisation, epidotisation, and chloritisation. The genesis of the deposit is up to today not determined and studies are few. However, the deposit's spatial proximity to a mineralised granodiorite dated at ca. 1.87 Ga offer some similarities to the Aitik deposit and its 1.89 Ga quartz monzodiorite. A primary magmatic origin with later IOCG overprint could therefore be a possibility.

Place, publisher, year, edition, pages
Society for Geology Applied to Mineral Deposits, 2017
National Category
Geology
Research subject
Ore Geology; Ore Geology
Identifiers
urn:nbn:se:ltu:diva-70289 (URN)000439764100240 ()978-2-9816898-0-1 (ISBN)
Conference
14th SGA Biennial Meeting on Mineral Resources to Discover, Quebec City, Canada, AUG 20-23, 2017
Available from: 2018-08-09 Created: 2018-08-09 Last updated: 2018-08-09Bibliographically approved
Wanhainen, C., Pålsson, B., Martinsson, O. & Lahaye, Y. (2017). Rare earth mineralogy in tailings from Kiirunavaara iron ore, northern Sweden: Implications for mineral processing. Minerals & metallurgical processing, 34(4), 189-200
Open this publication in new window or tab >>Rare earth mineralogy in tailings from Kiirunavaara iron ore, northern Sweden: Implications for mineral processing
2017 (English)In: Minerals & metallurgical processing, ISSN 0747-9182, Vol. 34, no 4, p. 189-200Article in journal (Refereed) Published
Abstract [en]

Four main and three minor rare-earth-element (REE)-bearing minerals were identified and quantified in the Kiirunavaara apatite iron ore tailings using optical microscopy, an electron probe microanalyzer (EPMA) and a mineral liberation analyzer, and their chemical compositions were analyzed by the EPMA and laser ablation inductively coupled plasmamass spectrometry. REEs are shown to be contained in the minerals apatite, monazite, allanite, titanite, zircon, thorite and synchysite. In zircon, thorite and synchysite, they occurred in only trace amounts and contributed limited amounts to the total REE budget, and these are consequently of minor importance. Monazite occurred as inclusions in apatite and as free particles, 90 percent liberated. Allanite occurred to some degree in mixed grains with magnetite but also as free particles. Monazite mainly reported to the apatite concentrate, while allanite and titanite largely went to the tailings, the latter preferably to those fractions smaller than 38 μm. The amount of titanite in the finest tailings fraction was 2.3 weight percent, containing close to 1 percent REEs, with heavy rare earth elements (HREEs) making up 28 percent of the total REEs. However, a texturally distinct group of titanite grains showed an HREE/REE ratio of up to 67 percent. Furthermore, titanum dioxide analyses indicate that titanite is preferentially released into the tailings from the secondary magnetic separation step in the concentrator. Our data therefore suggest that titanite, occasionally enriched in HREEs, can be extracted from the processing stream and might thus be considered a new source for REEs at Kiirunavaara and similar deposits.

Place, publisher, year, edition, pages
Society for Mining, Metallurgy and Exploration, 2017
National Category
Geology Metallurgy and Metallic Materials
Research subject
Ore Geology; Mineral Processing
Identifiers
urn:nbn:se:ltu:diva-66621 (URN)10.19150/mmp.7859 (DOI)000419794200005 ()2-s2.0-85032955143 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-11-17 (andbra)

Available from: 2017-11-17 Created: 2017-11-17 Last updated: 2018-03-26Bibliographically approved
Andersson, J. B. .., Bauer, T. E., Martinsson, O. & Wanhainen, C. (2017). The tectonic overprint on the Per Geijer apatite iron ores in Kiruna, northern Sweden. In: Mercier Langevin, P; Dube, B; Bardoux, M; Ross, PS; Dion, C (Ed.), Mineral Resources to Discover: . Paper presented at 14th SGA Biennial Meeting on Mineral Resources to Discover, Quebec City, Canada, AUG 20-23, 2017 (pp. 903-906). Society for Geology Applied to Mineral Deposits
Open this publication in new window or tab >>The tectonic overprint on the Per Geijer apatite iron ores in Kiruna, northern Sweden
2017 (English)In: Mineral Resources to Discover / [ed] Mercier Langevin, P; Dube, B; Bardoux, M; Ross, PS; Dion, C, Society for Geology Applied to Mineral Deposits , 2017, p. 903-906Conference paper, Published paper (Refereed)
Abstract [en]

This ongoing project focusses on the structural evolution of the Per Geijer apatite iron ores in Kiruna, northern Sweden. The Per Geijer iron ores are situated in a NNE-SSW trending shear zone. This study indicate that the shear zone was active during D2 E-W compression giving rise to dip-slip and oblique slip components. The ductile fabric is overprinted by brittle structures carrying Cu, possibly representing traces of a separate Iron Oxide Copper Gold event in northern Norrbotten.

Place, publisher, year, edition, pages
Society for Geology Applied to Mineral Deposits, 2017
National Category
Geology
Research subject
Ore Geology; Ore Geology
Identifiers
urn:nbn:se:ltu:diva-70285 (URN)000439764100223 (DOI)978-2-9816898-0-1 (ISBN)
Conference
14th SGA Biennial Meeting on Mineral Resources to Discover, Quebec City, Canada, AUG 20-23, 2017
Available from: 2018-08-09 Created: 2018-08-09 Last updated: 2018-08-09Bibliographically approved
Sarlus, Z., Martinsson, O., Bauer, T. E. & Wanhainen, C. (2017). Timing and tectonic setting of host rocks to the Malmberget AlO deposit, Sweden. In: Mercier Langevin, P; Dube, B; Bardoux, M; Ross, PS; Dion, C (Ed.), Mineral Resources to Discover: . Paper presented at 14th SGA Biennial Meeting on Mineral Resources to Discover, Quebec City, Canada, AUG 20-23, 2017 (pp. 959-962). Society for Geology Applied to Mineral Deposits
Open this publication in new window or tab >>Timing and tectonic setting of host rocks to the Malmberget AlO deposit, Sweden
2017 (English)In: Mineral Resources to Discover / [ed] Mercier Langevin, P; Dube, B; Bardoux, M; Ross, PS; Dion, C, Society for Geology Applied to Mineral Deposits , 2017, p. 959-962Conference paper, Published paper (Refereed)
Abstract [en]

Host felsic and intermediate meta-volcanic rocks to the Malmberget apatite iron ore (AlO) deposit have been investigated geochemically and geochronologically, the latter using the U-Pb method on a set of zircons. Results indicate emplacement age of 1.9 Ga for the felsic and intermediate volcanic rocks, potentially in an extensional environment. The zircon U-Pb radiometric ages are among the first conclusive ages with implicit constraint on the geological evolution of the northern Norrbotten ore district and Malmberget deposit.

Place, publisher, year, edition, pages
Society for Geology Applied to Mineral Deposits, 2017
National Category
Geology
Research subject
Ore Geology; Ore Geology
Identifiers
urn:nbn:se:ltu:diva-70281 (URN)000439764100237 ()978-2-9816898-0-1 (ISBN)
Conference
14th SGA Biennial Meeting on Mineral Resources to Discover, Quebec City, Canada, AUG 20-23, 2017
Available from: 2018-08-09 Created: 2018-08-09 Last updated: 2018-08-09Bibliographically approved
Martinsson, O., Billström, K., Broman, C., Weihed, P. & Wanhainen, C. (2016). Metallogeny of the Northern Norrbotten Ore Province, northern Fennoscandian Shield with emphasis on IOCG and apatite-iron ore deposits (ed.). Paper presented at . Ore Geology Reviews, 78, 447-492
Open this publication in new window or tab >>Metallogeny of the Northern Norrbotten Ore Province, northern Fennoscandian Shield with emphasis on IOCG and apatite-iron ore deposits
Show others...
2016 (English)In: Ore Geology Reviews, ISSN 0169-1368, E-ISSN 1872-7360, Vol. 78, p. 447-492Article in journal (Refereed) Published
Abstract [en]

The Northern Norrbotten Ore Province in northernmost Sweden includes the type localities for Kiruna-type apatite iron deposits and has been the focus for intense exploration and research related to Fe oxide-Cu-Au mineralisation during the last decades. Several different types of Fe-oxide and Cu-Au ± Fe oxide mineralisation occur in the region and include: stratiform Cu ± Zn ± Pb ± Fe oxide type, iron formations (including BIF's), Kiruna-type apatite iron ore, and epigenetic Cu ± Au ± Fe oxide type which may be further subdivided into different styles of mineralisation, some of them with typical IOCG (Iron Oxide-Copper-Gold) characteristics. Generally, the formation of Fe oxide ± Cu ± Au mineralisation is directly or indirectly dated between ~ 2.1 and 1.75 Ga, thus spanning about 350 m.y. of geological evolution.The current paper will present in more detail the characteristics of certain key deposits, and aims to put the global concepts of Fe-oxide Cu-Au mineralisations into a regional context. The focus will be on iron deposits and various types of deposits containing Fe-oxides and Cu-sulphides in different proportions which generally have some characteristics in common with the IOCG style. In particular, ore fluid characteristics (magmatic versus non-magmatic) and new geochronological data are used to link the ore-forming processes with the overall crustal evolution to generate a metallogenetic model.Rift bounded shallow marine basins developed at ~ 2.1–2.0 Ga following a long period of extensional tectonics within the Greenstone-dominated, 2.5–2.0 Ga Karelian craton. The ~ 1.9–1.8 Ga Svecofennian Orogen is characterised by subduction and accretion from the southwest. An initial emplacement of calc-alkaline magmas into ~ 1.9 Ga continental arcs led to the formation of the Haparanda Suite and the Porphyrite Group volcanic rocks. Following this early stage of magmatic activity, and separated from it by the earliest deformation and metamorphism, more alkali-rich magmas of the Perthite Monzonite Suite and the Kiirunavaara Group volcanic rocks were formed at ~ 1.88 Ga. Subsequently, partial melting of the middle crust produced large volumes of ~ 1.85 and 1.8 Ga S-type granites in conjunction with subduction related A −/I-type magmatism and associated deformation and metamorphismIn our metallogenetic model the ore formation is considered to relate to the geological evolution as follows. Iron formations and a few stratiform sulphide deposits were deposited in relation to exhalative processes in rift bounded marine basins. The iron formations may be sub-divided into BIF- (banded iron formations) and Mg-rich types, and at several locations these types grade into each other. There is no direct age evidence to constrain the deposition of iron formations, but stable isotope data and stratigraphic correlations suggest a formation within the 2.1–2.0 Ga age range. The major Kiruna-type ores formed from an iron-rich magma (generally with a hydrothermal over-print) and are restricted to areas occupied by volcanic rocks of the Kiirunavaara Group. It is suggested here that 1.89–1.88 Ga tholeiitic magmas underwent magma liquid immiscibility reactions during fractionation and interaction with crustal rocks, including metaevaporites, generating more felsic magmatic rocks and Kiruna-type iron deposits. A second generation of this ore type, with a minor economic importance, appears to have been formed about 100 Ma later. The epigenetic Cu-Au ± Fe oxide mineralisation formed during two stages of the Svecofennian evolution in association with magmatic and metamorphic events and crustal-scale shear zones. During the first stage of mineralisation, from 1.89–1.88 Ga, intrusion-related (porphyry-style) mineralisation and Cu-Au deposits of IOCG affinity formed from magmatic-hydrothermal systems, whereas vein-style and shear zone deposits largely formed at c. 1.78 Ga.The large range of different Fe oxide and Cu-Au ± Fe oxide deposits in Northern Norrbotten is associated with various alteration systems, involving e.g. scapolite, albite, K feldspar, biotite, carbonates, tourmaline and sericite. However, among the apatite iron ores and the epigenetic Cu-Au ± Fe oxide deposits the character of mineralisation, type of ore- and alteration minerals and metal associations are partly controlled by stratigraphic position (i.e. depth of emplacement). Highly saline, NaCl + CaCl2 dominated fluids, commonly also including a CO2-rich population, appear to be a common characteristic feature irrespective of type and age of deposits. Thus, fluids with similar characteristics appear to have been active during quite different stages of the geological evolution. Ore fluids related to epigenetic Cu-Au ± Fe oxides display a trend with decreasing salinity, which probably was caused by mixing with meteoric water. Tentatively, this can be linked to different Cusingle bondAu ore paragenesis, including an initial (magnetite)-pyrite-chalcopyrite stage, a main chalcopyrite stage, and a late bornite stage.Based on the anion composition and the Br/Cl ratio of ore related fluids bittern brines and metaevaporites (including scapolite) seem to be important sources to the high salinity hydrothermal systems generating most of the deposits in Norrbotten. Depending on local conditions and position in the crust these fluids generated a variety of Cu-Au deposits. These include typical IOCG-deposits (Fe-oxides and Cu-Au are part of the same process), IOCG of iron stone type (pre-existing Fe-oxide deposit with later addition of Cu-Au), IOCG of reduced type (lacking Fe-oxides due to local reducing conditions) and vein-style Cu-Au deposits. From a strict genetic point of view, IOCG deposits that formed from fluids of a mainly magmatic origin should be considered to be a different type than those deposits associated with mainly non-magmatic fluids. The former tend to overlap with porphyry systems, whereas those of a mainly non-magmatic origin overlap with sediment hosted Cu-deposits with respect to their origin and character of the ore fluids.

National Category
Geology
Research subject
Ore Geology
Identifiers
urn:nbn:se:ltu:diva-12551 (URN)10.1016/j.oregeorev.2016.02.011 (DOI)000378450300028 ()2-s2.0-84968909194 (Scopus ID)bb499b14-f022-4437-a476-ca37d5cb06f5 (Local ID)bb499b14-f022-4437-a476-ca37d5cb06f5 (Archive number)bb499b14-f022-4437-a476-ca37d5cb06f5 (OAI)
Note
Validerad; 2016; Nivå 2; 20160317 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-0935-3430

Search in DiVA

Show all publications