DOCSLIB.ORG

Overview of Talc Resources in the Altermark Talc Province, Northern Norway, and Possible Uses of the Talc Ore

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Overview of Talc Resources in the Altermark Talc Province, Northern Norway, and Possible Uses of the Talc Ore NGU-BULL 436, 2000 - PAGE 93 Overview of talc resources in the Altermark talc province, northern Norway, and possible uses of the talc ore TOR ARNE KARLSEN, EDVIN RIAN & ODLEIV OLESEN Karlsen, T.A., Rian, E. & Olesen, O.: 2000: Overview of talc resources and reserves in the Altermark talc province, northern Norway and possible uses of the talc ore. Norges geologiske undersøkelse Bulletin, 436, 93-102. Active prospecting during the past 10 years has proved that the Altermark area contains much more talc than previously recognised. In the Nakkan-Esjeklumpen area, 10 M tonnes or more of talc-carbonate ore are probably present, distributed in ultramafic bodies. The ore, which occurs as one of several layers within compositionally zoned ultramafic lenses dominated by antigorite serpentinites, has the following general mineralogy: talc (45-65 %), carbonate (30-50 %), chlorite (0-4 %) and magnetite (0-3 %). Relative to other known similar deposits, the ore is rather coarse-grained, and the minerals tend to be idioblastic. Several products can be made from the talc-carbonate ore. By applying flotation or other kinds of mineral separation techniques, it is likely that high-quality talc-concentrate could be made in addition to talc-carbonate mixtures. A concentrate of by-product breunnerite would possibly be of economic value. Tor Arne Karlsen, Geological Survey of Norway, N-7491 Trondheim, Norway; Edvin Rian, Norwegian Talc Altermark AS, N- 8616, Norway; Odleiv Olesen, Geological Survey of Norway, N-7491 Trondheim, Norway. Introduction Geological setting Economic talc1 mineralisation is normally associated either The Altermark area is situated about 20 km west of Mo i Rana, with dolomite or with ultramafic rocks (i.e. ‘ultramafic’ talc). northern Norway (Fig. 1). The rocks belong to the Rödingsfjäl- All known major occurrences of talc in Norway are of the let Nappe Complex (Gustavson & Gjelle 1991) of the Upper- ultramafic type, and are associated with serpentinised ophi- most Allochthon (Roberts & Gee 1985) of the Caledonides. olitic ultramafites, ultramafic conglomerates or solitary ultra- The Rödingsfjället Nappe Complex and the overlying mafic lenses. Helgeland Nappe Complex are the two dominating nappe Norwegian Talc AS, owned by Plüss Staufer AG, is the complexes along the Nordland coast. These nappe com- major talc company in Norway, and produces talc from ultra- plexes contain numerous ultramafic lenses of somewhat dis- mafic rocks in Altermark, Nordland county, northern Norway puted origin (Karlsen 1995). Immediately to the south of (Fig. 1). In the Altermark area, the ultramafic lenses are found Helgeland, ophiolitic ultramafite with associated talc occurs to be particularly well talcified, and the area is described as a on the island of Leka in Nord-Trøndelag. North of Rødøy talc province. Due to a shortage of ore reserves in the late (Bang 1985), ophiolite complexes as such have not been rec- 1980s, a prospecting campaign was carried out during the ognised, and the ultramafites occur as solitary lenses. Around following years (1989-1995). Work started with drilling and the basement windows Sjona, Høgtuva and Svartisen, soli- investigation of the Straumdalen talc deposit (Holter 1990), tary ultramafic or ultramafic/mafic lenses are widespread, sit- and was followed up by a more intensive survey including uated predominantly within the Rödingsfjället Nappe Com- airborne geophysics (Mogaard & Walker 1991, Karlsen & plex (Fig. 1). Olesen 1991), regional mapping, detailed deposit mapping, and comprehensive mineralogical studies (Karlsen 1995). This campaign, which has been followed up by drilling, Tectonostratigraphy turned out to be successful, and several millions of tons of In the investigated area, the Rödingsfjället Nappe Complex talc-carbonate rocks were detected, both within and outside consists of three tectonic units: the Tjørnrasta Nappe, the the existing talc mine. The Nakkan deposit was detected by Straumbotn Nappe (Søvegjarto et al. 1988) and the Slettefjel- airborne geophysical exploration (Mogaard & Walker 1991, let Unit (Fig. 2). The Tjørnrasta Nappe is dominated by Karlsen & Olesen 1991, 1996), and is today the major target quartzo-feldspathic gneisses and quartz-rich mica schists for future exploitation. In the present paper, the general while the Straumbotn Nappe comprises kyanite-staurolite geology and prospects in the Altermark area are presented. bearing garnet-mica schists, marbles and amphibolites. The tectonised transition from the Tjørnrasta Nappe to the over- lying Straumbotn Nappe is marked by occurrences of 1. Talc – both pure mineralogical talc and industrial talc which may strongly deformed graphitic schists, which outline the thrust contain variable amounts of magnesite, chlorite etc. zone of the ‘Straumbotn Nappe floor thrust’ (SNft). The Slet- NGU-BULL 436, 2000 - PAGE 94 TOR ARNE KARLSEN, EDVIN RIAN & ODLEIV OLESEN Fig. 1. Tectonostratigraphic map of western Helgeland and occurrences of ultramafic rocks. Scale of ultramafic rocks is exaggerat- ed by around 100 %. The investigated area is outlined. Compiled from Søvegjarto (1977), Johnsen (1983), Søvegjarto et al. (1988, 1989) and Gustavson & Gjelle (1991). tefjellet Unit, which is situated above the Straumbotn Nappe, Deformation events post-dating the peak of metamor- is interpreted to be a structural repetition of the Tjørnrasta phism are represented by D2 and D3, which created meso- to Nappe, and contains similar rock types (Karlsen 1995). macroscopic scale folds that deform the D1 structures. The The ultramafic rocks, which can be classified as so-called Slettefjellet fold, which is the dominant macroscopic struc- solitary alpine-type ultramafites (Quale & Stigh 1985), occur ture in the area, is interpreted to be an overturned, tight, F2 as lenses within the Straumbotn Nappe and are usually asso- antiform with an axial surface dipping at about 40° towards ciated with the SNft (Fig. 2). It is possible that certain revisions SE. The Slettefjellet fold changes trend when traced west- will have to be made to the standard tectonostratigraphy of ward along the Sjona gneiss dome (interpreted from Gustav- the region. son & Gjelle 1991), probably as a result of the dome geometry The structural history of the area is complex, and will be of the Precambrian window. described in detail in a separate paper; only a summary is Décollement thrusting is observed along the outermost given here. Four deformation events have been recognised, parts of the ultramafic rocks where the enveloping rocks D1, D2, D3 and D4 (Karlsen 1995). The first deformation event, have been intensively folded by F2/F3 and slid along the bor- D1, created the well-developed metamorphic foliation, S1, der of the ultramafites. which is the dominant micro-/mesoscopic structure, and Geothermobarometric investigations have indicated that defined by mica, hornblende, kyanite, staurolite, graphite, all the rocks of the Rödingsfjället Nappe Complex in the epidote and elongated aggregates of quartz and feldspars. investigated area were metamorphosed at amphibolite D1 also created microscopic to macroscopic F1 folds, which facies at high-pressure conditions during D1 (Karlsen 1995). are moderately inclined, and weakly plunging isoclinal folds with a strongly developed penetrative axial plane cleavage Compositional zoning of the (S1). Most of the F1 fold axes parallel the main E-plunging, L1 ultramafic lenses stretching lineation. L1a is a micro-/mesoscopic stretching lineation defined by strongly elongated aggregates of quartz The ultramafic lenses are actually parts of composite mafic/ and/or feldspars and by a parallel orientation of the minerals ultramafic lenses, although the mafic parts, now represented kyanite, staurolite and hornblende. The L1a lineation gener- by amphibolite, are not always easy to recognise. The ultra- ally plunges at about 0-30° towards E or ESE. L1b is a meso-/ mafic parts of the lenses are mineralogically zoned, and three macroscopic stretching lineation defined by the longest axes major zones occur (Fig. 3): (1) Serpentinitic core, (2) Talc-car- of meso- and macroscale boudins of serpentinites and locally bonate zone, (3) Monomineralic rocks in the rim. The serpen- amphibolites plunging at around 20-30° towards E. All of the tinite consists predominantly of interpenetrating textured interpreted nappe boundaries within the Rödingsfjället antigorite and 5-20 % magnetite. Especially ferrite-chromite, Nappe Complex are interpreted to be of early D1 age. but locally also relics of olivine and clinopyroxene, are TOR ARNE KARLSEN, EDVIN RIAN & ODLEIV OLESEN NGU-BULL 436, 2000 - PAGE 95 Fig. 2. Simplified geological map of the investigated area with names of the ultramafic lenses and localities of cross-sections. Abbrevations: A = Anna- bergan ultramafite, SE = Store Esjeklumpen, LE = Lille Esjeklumpen, R = Remlia. N = Nakkan (situated about 150 m below surface). Nappes: Tj.Na = Tjørn- rasta Nappe, Tj.Na2 = Tjørnrasta Nappe inverted, Str.Na = Straumbotn Nappe. Cross-sections are shown in Figs. 4 & 6. present in subordinate amounts. Some of the ultramafic chemically zoned breunnerite, while dolomite may be cores carry lenses of primary clinopyroxenite, dunite, chrom- present locally in subordinate amounts. A more detailed itite and also rodingite. The rodingite, which probably repre- description of this rock, which is the primary ore, is given sent metasomatised mafic rocks, has been described only below. The monomineralic rocks in the rim consist of talc once previously
Load more

Recommended publications
  • Hemnesberget Ran Orden 12 Nesna Sandnessjøen
    GUIDE 2017 – magic and real www.visithelgeland.com R T I G R U T H U E N Slettnes Kinnarodden Gamvik Knivskjelodden Nordkapp Mehamn Omgangs- Gjesværstappan Tu orden stauren Hjelmsøystauren Hornvika Skjøtningberg Kjølnes Helnes Skarsvåg Tanahorn Gjesvær Sværholt- Kjølle ord Kamøyvær Finnkirka MAGERØYA klubben NORDKYN- Kvitnes Berlevåg Sand orden Fruholmen HALVØYA Makkaur H Skips orden ongs orden U Sværholdt K RT HJELMSØYA Sarnes I G R Nordvågen Ki ord Store Molvik Veines U T Ingøy Dy ord Skjånes E N Havøysund Måsøy Honningsvåg Eids orden Kongs ord Sylte ordstauran Gunnarnes Hopseidet Hops orden Tu ord Båts ord Hamningberg Troll ord/ a v Kå ord Lang ordnes l ROLVSØYA Gulgo e d Sylte ord Sylte orden Selvika r Bak orden Lang orden o Rygge ord SVÆRHOLT- s Hornøya g Lakse orden HALVØYA Nervei Davgejavri n N o E K lva Vardø T Sylte orde U Rolvsøysundet R Laggo Tana orden Qædnja- G Repvåg Oksøy- I Sne ord javri vatnet T R PORSANGER- Store Veidnes Akkar ord U VARANGER- H Slotten HALVØYA Tamsøya Bekkar ord HALVØYA VARANGERHALVØYA Kiberg Revsbotn Lebesby Langnes NASJONALPARK K Forsøl Lille ord Smal orden omag Skippernes Skjånes Sund- J elv a a vatnet Austertana k Revsneshamn Smal ord o Ska Komagvær b l lel Lundhamn s v Helle ord e R I ord l u v Langstrand s Ruste elbma a Hammerfest s v a l e Vestertana lv Nordmannset Iordellet e KVALØYA a Friar ord y Sandøybotn Kokelv Sandlia Lotre 370 moh b Falkeellet Rype ord Smør ord e g Dønnes ord Slettnes r 545 m Sand orden Porsanger orden e Kjerringholmen Akkar ord B Stuorra Gæssejavri Masjokmoen Sørvær Lille
    [Show full text]
  • Serie B 1995 Vo!. 42 No. 2 Norwegian Journal of Entomology
    Serie B 1995 Vo!. 42 No. 2 Norwegian Journal of Entomology Publ ished by Foundation for Nature Research and Cultural Heritage Research Trondheim Fauna norvegica Ser. B Organ for Norsk Entomologisk Forening Appears with one volume (two issues) annually. also welcome. Appropriate topics include general and 1Jtkommer med to hefter pr. ar. applied (e.g. conservation) ecology, morphology, Editor in chief (Ansvarlig redakt0r) behaviour, zoogeography as well as methodological development. All papers in Fauna norvegica are Dr. John O. Solem, University of Trondheim, The reviewed by at least two referees. Museum, N-7004 Trondheiln. Editorial committee (Redaksjonskomite) FAUNA NORVEGICA Ser. B publishes original new information generally relevant to Norwegian entomol­ Arne C. Nilssen, Department of Zoology, Troms0 ogy. The journal emphasizes papers which are mainly Museum, N-9006 Troms0, Ole A. Scether, Museum of faunal or zoogeographical in scope or content, includ­ Zoology, Musepl. 3, N-5007 Bergen. Reidar Mehl, ing check lists, faunal lists, type catalogues, regional National Institute of Public Health, Geitmyrsveien 75, keys, and fundalnental papers having a conservation N-0462 Oslo. aspect. Subnlissions must not have been previously Abonnement 1996 published or copyrighted and must not be published Medlemmer av Norsk Entomologisk Forening (NEF) subsequently except in abstract form or by written con­ far tidsskriftet fritt tilsendt. Medlemlner av Norsk sent of the Managing Editor. Ornitologisk Forening (NOF) mottar tidsskriftet ved a Subscription 1996 betale kr. 90. Andre ma betale kr. 120. Disse innbeta­ Members of the Norw. Ent. Soc. (NEF) will receive the lingene sendes Stiftelsen for naturforskning og kuItur­ journal free. The membership fee of NOK 150 should be minneforskning (NINA-NIKU), Tungasletta 2, N-7005 paid to the treasurer of NEF, Preben Ottesen, Gustav Trondheim.
    [Show full text]
  • Not for Release, Publication Or Distribution, in Whole Or in Part
    NOT FOR RELEASE, PUBLICATION OR DISTRIBUTION, IN WHOLE OR IN PART DIRECTLY OR INDIRECTLY, IN AUSTRALIA, CANADA, JAPAN, HONG KONG OR THE UNITED STATES OR ANY OTHER JURISDICTION IN WHICH THE RELEASE, PUBLICATION OR DISTRIBUTION WOULD BE UNLAWFUL. THIS ANNOUNCEMENT DOES NOT CONSTITUTE AN OFFER OF ANY OF THE SECURITIES DESCRIBED HEREIN. Rana Gruber AS: Contemplated secondary sale and listing on Euronext Growth Oslo Mo i Rana, 11 February 2021. Rana Gruber AS (“Rana Gruber” or the “Company”), one of the largest mining and iron ore beneficiation companies in Norway, has engaged Clarksons Platou Securities AS, DNB Markets, a part of DNB Bank ASA, and SpareBank 1 Markets AS (the “Managers”) to advise on and effect a contemplated secondary sale of up to NOK 925 million in existing shares in the Company (the “Offering”). "We have a leading position with more than 200 years of mining experience, a vast resource base and ambitions to become the first CO2-free iron ore producer by 2025. I’m proud of all my colleagues and the job we are doing every day, providing customers in various industries with iron ore for use in cars, buildings, and other consumer goods. A listing of the shares will enhance access to a diverse capital base, while at the same time maintaining a strong backbone of northern Norwegian capital with LNS Mining as the main owner," says Gunnar Moe, CEO of Rana Gruber. "The planned listing on Euronext Growth Oslo will create an opportunity for new investors to take part in Rana Gruber’s development and value creation together with existing owners.
    [Show full text]
  • The Grønli–Seter Karst System, Northern Norway 61
    NORWEGIAN JOURNAL OF GEOLOGY Characterisation of a post-glacial invasion aquifer: the Grønli–Seter karst system, northern Norway 61 Characterisation of a post-glacial invasion aquifer: the Grønli–Seter karst system, northern Norway Rannveig Øvrevik Skoglund & Stein-Erik Lauritzen Skoglund, R.Ø. & Lauritzen, S.-E.: Characterisation of a post-glacial invasion aquifer: the Grønli–Seter karst system, northern Norway. Norwegian Journal of Geology, Vol 93, pp 61–73, Trondheim 2013. ISSN 029-196X. The present-day Grønli–Seter karst aquifer in Rana is fed by a surface stream that invades a relict cave system, so that the present hydrology is constrained by pre-existing geometry. This type of karst aquifer is quite common in the glacially sculptured landscape of Norway, where speleo- genesis displays a strong imprint from glacier-ice contact. The Grønli–Seter cave system is situated in the hillside of Røvassdalen, with passage morph ology and palaeoflow marks indicating development below the watertable and by ascending water flow in the presence of a glacier filling up the valley. The aquifer has a mean annual discharge of about 0.13 m3 s-1, which makes up about half of the total runoff from Strokbekken from where it is sourced. Hydrograph and quantitative dye-tracer experiments demonstrated that the aquifer is totally dominated by conduits and com- prises three sections with distinctly different cross-sectional areas. The lower part of the traced aquifer comprises essentially phreatic (submerged) conduits with a mean cross-sectional area of about 4.5 m2 and a static volume of minimum 4000 m3. In the upper sections, the ratio of submerged, water-filled passages is lower, and the cross-sectional area of the water flow is smaller, but with a greater increase during floods.
    [Show full text]
  • Viewers Deta Gasser and Fer- Ing Sinistral Shear, the Collision May Have Become Nando Corfu Provided Insightful Comments and Construc- More Orthogonal (Soper Et Al
    Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021 Late Neoproterozoic–Silurian tectonic evolution of the Rödingsfjället Nappe Complex, orogen-scale correlations and implications for the Scandian suture Trond Slagstad1*, Kerstin Saalmann1, Chris L. Kirkland2, Anne B. Høyen3, Bergliot K. Storruste4, Nolwenn Coint1, Christian Pin5, Mogens Marker1, Terje Bjerkgård1, Allan Krill4, Arne Solli1, Rognvald Boyd1, Tine Larsen Angvik1 and Rune B. Larsen4 1Geological Survey of Norway, Trondheim, Norway 2Centre for Exploration Targeting Curtin Node, School of Earth and Planetary Sciences, Curtin University, Perth, Australia 3Department of Geology and Mineral Resources Engineering, Norwegian University of Science and Technology, Trondheim, Norway 4Department of Geosciences and Petroleum, Norwegian University of Science and Technology, Trondheim, Norway 5Département de Géologie, C.N.R.S. & Université Blaise Pascal, 5 rue Kessler, 63038 Clermont-Ferrand, France TS, 0000-0002-8059-2426; CLK, 0000-0003-3367-8961; NC, 0000-0003-0058-722X; AK, 0000-0002-5431-3972; RBL, 0000-0001-9856-3845 Present addresses: ABH, The Norwegian Directorate of Mining, Trondheim, Norway; BKS, Brønnøy Kalk, Velfjord, Norway *Correspondence: [email protected] Abstract: The Scandinavian Caledonides consist of disparate nappes of Baltican and exotic heritage, thrust southeastwards onto Baltica during the Mid-Silurian Scandian continent–continent collision, with structurally higher nappes inferred to have originated at increasingly distal positions to Baltica. New U–Pb zircon geochro- nological and whole-rock geochemical and Sm–Nd isotopic data from the Rödingsfjället Nappe Complex reveal 623 Ma high-grade metamorphism followed by continental rifting and emplacement of the Umbukta gabbro at 578 Ma, followed by intermittent magmatic activity at 541, 510, 501, 484 and 465 Ma.
    [Show full text]
  • Sluttrapport
    2020:00148 - Fortrolig Sluttrapport Mineralprosjektet på Indre Helgeland Forfatter Per Helge Høgaas Befaring i Mofjellet berghaller SINTEF Industri Prosessmetallurgi og råmateriale 2020-03-18 SINTEF Industri Postadresse: Postboks 4760 Torgarden Sluttrapport 7465 Trondheim Sentralbord: 40005100 [email protected] Foretaksregister: Mineralprosjektet på Indre Helgeland NO 919 303 808 MVA EMNEORD: VERSJON DATO Mineraler 1 2020-03-18 Industri Verdiskaping FORFATTER Per Helge Høgaas OPPDRAGSGIVER OPPDRAGSGIVERS REF. Indre Helgeland Regionråd Arne Langset / Svenn Tovås PROSJEKTNR ANTALL SIDER OG VEDLEGG: 102014651 62 SAMMENDRAG Overskrift sammendrag Rapporten gir en oversikt over gjennomførte aktiviteter og resultater fra Mineralprosjektet på Indre Helgeland. SIGNATUR UTARBEIDET AV Per Helge Høgaas KONTROLLERT AV SIGNATUR Casper van der Eijk GODKJENT AV SIGNATUR Rune Holmen RAPPORTNR ISBN GRADERING GRADERING DENNE SIDE 2020:00148 ISBN-nummer Fortrolig Fortrolig 1 av 62 Historikk VERSJON DATO VERSJONSBESKRIVELSE 1 2020-03-18 Mineralprosjektet på Indre Helgeland PROSJEKTNR RAPPORTNR VERSJON 102014651 2020:00148 1 2 av 62 Innholdsfortegnelse 1 Nasjonal bakgrunn ....................................................................................................................... 4 1.1 Regional bakgrunn ......................................................................................................................... 5 2 Målsetting ...................................................................................................................................
    [Show full text]
  • Marine and Riverine Discharges of Mine Tailings 2012
    International Assessment of Marine and Riverine Disposal of Mine Tailings Study commissioned by the Office for the London Convention and Protocol and Ocean Affairs, IMO, in collaboration with the United Nations Environment Programme (UNEP) Global Programme of Action May 2013 About this report This report presents a world-wide inventory of operating mines that dispose of mine tailings to marine and riverine waters and a review of what is known about the environmental impacts of those discharges. The report was commissioned by the Office for the London Convention and Protocol and Ocean Affairs, Marine Environment Division, International Maritime Organization, in collaboration with the United Nations Environment Programme (UNEP) Global Programme of Action, and was compiled by a consultant, Craig Vogt Inc Ocean & Coastal Environmental Consulting. Disclaimer The views expressed in this document are those of the author(s) and may not necessarily reflect those of the organization (IMO). IMO shall not be liable to any person or organization for any loss, damage or expense caused by reliance on the information or advice in this document or howsoever provided. IMO does not take responsibility for the implications of the use of any information or data presented in this publication and the publication does not constitute any form of endorsement whatsoever by IMO. Individuals and organisations that make use of any data or other information contained in the report do so entirely at their own risk. Marine and Riverine Discharges of Mine Tailings 2012 Preface This report presents a world-wide inventory of operating mines that dispose of mine tailings to marine and riverine waters and a review of what is known about the environmental impacts of those discharges.
    [Show full text]
  • The Coastal Road (State Highway 17) from Holandsfjorden to Nesna
    The coastal road (state highway 17) from Holandsfjorden to Nesna 93 Locality 39 - Blokktinden, Tjong On the road to Tjong and onwards to Reppa there is a good view towards Blokktinden and its very large avalanche cone. Blokktinden is carved in granitic gneiss and belongs to one of the Precambrian basement windows. Strong vertical jointing in the bedrock is one of the reasons for the large quantities of scree material which have accumulated here. The main shore line forms a break in the avalanche slope and can be seen as a horizontal line. Here it represents the marine limit and is clearly developed in the fallen material. This means that most of the cone is a little older than the last part of the Younger Dryas. Probably most of the stoneblocks fell from the mountain wall a little after the mountain emerged from the ice masses 12,000-11,000 years ago. The climate during the first part of Younger Dryas time was very cold which enhanced fracturing of the rock walls and initiated stone-block production. Blokktinden with its 400 m avalanche cone, looking south from Tjong. Photo: Terje H. Bargel. 94 Locality 40 - Nordværnes On a branch road, about 15 km from Straumsvika and only a few hundred metres from Nordværnes, is a body of peridotite (olivine/pyroxene rock). It is easily seen because of ifs reddish yellow alteration colour. Parts of this body, particularly the marginal zone and intersecting veins, are very special. In a groundmass which consists mostly of orthopyroxene there are olivine crystals 5 cm to 1 m in length and randomly orientated.
    [Show full text]
  • Relation Between Seismicity and Tectonic Structures Offshore and Onshore Nordland, Northern Norway
    NORWEGIAN JOURNAL OF GEOLOGY Vol 97 Nr. 3 https://dx.doi.org/10.17850/njg97-3-02 Relation between seismicity and tectonic structures offshore and onshore Nordland, northern Norway Ilma Janutyte1, Conrad Lindholm1 & Odleiv Olesen2 1 NORSAR, 2027 Kjeller, Norway. 2 Geological Survey of Norway, P. O. Box 6315 Torgard, 7491 Trondheim, Norway. E-mail corresponding author (Ilma Janutyte): [email protected] A temporary network of 27 seismic stations was deployed from August 2013 to May 2016 along the coast of Nordland, northern Norway, where northwestern Europe’s largest earthquake of magnitude 5.8 over the last two centuries has occurred. The NEONOR2 project aimed to improve our understanding of neotectonic movements, stress regime and the overall seismicity pattern in Nordland and the adjacent offshore areas. From the data retrieved from the temporary NEONOR2 deployment and the permanent stations of the Norwegian National Seismic Network, nearly 1250 earthquakes were located in the study area. During the monitoring period, the seismic activity in Nordland was mostly sporadic, but in some areas it was clearly episodic, especially to the west of the Svartisen glacier where an earthquake swarm with several hundred small seismic events was recorded from April 2015 until March 2016. The shallow swarm activity could possibly be partly related to the changes in the glacier mass and groundwater conditions. During the monitoring period, no earthquakes were recorded along the prominent Bivrost transfer zone, on the Trøndelag Platform and in the larger Vestfjorden Basin area, and it could therefore be concluded that these areas are aseismic; however, only three years of monitoring in such areas of low deformation rates is not enough to make strict conclusions.
    [Show full text]
  • Mineralogy and Texture of the Storforshei Iron Formation, and Their Effect on Grindability
    Mineralogy and texture of the Storforshei iron formation, and their effect on grindability Marte Kristine Tøgersen1,2, Rolf Arne Kleiv1, Steinar Ellefmo1 and Kurt Aasly1 1Department of Geoscience and Petroleum, Norwegian University of Science and Technology, Sem Sælandsveg 1, N-7491 Trondheim, Norway 2Rana Gruber AS, Mjølanveien 29, Gullsmedvik, 8601 Mo i Rana, Norway Abstract Investigating how ore mineralogy and texture affect the recovery from the processing plant is important for any mining operation. The results will assist in production planning and optimising the utilisation of a deposit. Easily available validated tests are desirable and useful. The Storforshei iron formation (IF) consists of several iron oxide deposits with mineralogical and textural differences. Although the Fe grades of the ores are similar, mineralogical and textural characteristics of the deposits affect the individual recoveries from the magnetic separation. For this paper three of the ore deposits were sampled, and important mineralogical and textural properties were investigated and tested. The investigations included geological mapping and optical microscopy, and the test work involved surface hardness measurements by Schmidt hammer and Equotip, and autogenous milling tests (i.e., grindability). The aim of the study was to investigate whether ore mineralogy and textures can be correlated to surface hardness measurements, and whether these three parameters can be used to evaluate grindability. The ores were classified into six ore types based on mineralogy and textures. The results show that the ore mineralogy and texture influence the surface hardness. Fine-grained ore types with irregular-to-no visible grain boundaries have higher surface hardness than coarser-grained ore types with straight grain boundaries.
    [Show full text]
  • Aktsomhetskart for Jordfallshull I Nordland: En Forstudie
    Aktsomhetskart for jordfallshull i Nordland: en forstudie Mastergradsoppgave i kvartærgeologi og paleoklima Ragnhild Austbø Kjønsøy Institutt for geovitenskap Universitetet i Bergen Juni 2019 Sammendrag Store deler av Nordland utgjør områder hvor karstbergarter er tildekket av kvartære løsmasser. Ved slike forhold kan suffosjonsdoliner og katastrofale jordfallshull utvikles. Jordfallshull er en type doline (lukket karstforsenkning) i landoverflaten som utløses plutselig fra kollaps av et underliggende hulrom i et løsmassedekke. Utvikling av jordfallshull har tidligere hatt store konsekvenser for bebyggelse i Nordland, men studier av hvilke områder som er av risiko har ikke blitt gjort før. Denne forstudien har hatt som formål å undersøke mulighetene for å produsere aktsomhetskart for geofaren. Gjennom GIS-baserte analyser i programvaren ArcGIS har aktsomhetsområder blitt definert, en automatisk metode for å detektere doliner har blitt forsøkt utviklet, og forståelse av landskaps- og glasialhistorie har blitt knyttet opp mot dagens fordeling av doliner. Produserte polygoner av aktsomhetsområder viser at store deler av områdene i Nordland er i risiko for jordfallshullutvikling, og flere områder av allerede etablert infrastruktur og bebyggelse ligger innenfor polygonene. En automatisk metode for å detektere doliner fra LiDAR-generert DTM med 1 meters oppløsning har vist seg å ha stor overordnet nøyaktighet i forhold til tradisjonell kartlegging av lukkede forsenkninger. Resultat fra automatisk metode viser at kartlagte bergartsgrenser i Nordland er unøyaktige, og medfører store feilkilder for å definere aktsomhetsområder. Tolkning av dolinestatistikk generert fra automatisk metode viser at det er to populasjoner doliner i Nordland; preglasiale og postglasiale. I områder under marin grense virker det til å være størst nydannelse av suffosjonsdoliner og jordfalshull.
    [Show full text]
  • Rana Gruber AS (A Private Limited Liability Company Incorporated Under the Laws of Norway)
    INFORMATION DOCUMENT Rana Gruber AS (A private limited liability company incorporated under the laws of Norway) Admission to trading of shares on Euronext Growth Oslo ________________________________________________________ This information document (the "Information Document") has been prepared by Rana Gruber AS (the "Company" or "Rana Gruber" and, together with its subsidiary, the "Group") solely for use in connection with the admission to trading of the Company's 37,392,000 shares, each with a nominal value of NOK 0.25 (the "Shares") on Euronext Growth, operated by Oslo Børs ("Euronext Growth Oslo"). The Company has applied for admission to trading of its Shares on Euronext Growth Oslo and it is expected that the Shares will start trading on or about 26 February 2021 under the ticker symbol "RANA". The present Information Document has been drawn up under the responsibility of the Company. It has been reviewed by the Euronext Growth Advisors and has been subject to an appropriate review of its completeness, consistency and comprehensibility by Euronext Growth Oslo. Euronext Growth is a market operated by Euronext. Companies on Euronext Growth, a multilateral trading facility (MTF), are not subject to the same rules as companies on a Regulated Market (a main market). Instead they are subject to a less extensive set of rules and regulations adjusted to small growth companies. The risk in investing in a company on Euronext Growth may therefore be higher than investing in a company on a Regulated Market. Investors should take this into account when making investment decisions. The present Information Document does not constitute a prospectus within the meaning of Regulation (EU) 2017/1129 of the European Parliament and of the Council of 14 June 2017 on the prospectus to be published when securities are offered to the public or admitted to trading on a regulated market, and repealing Directive 2003/71.
    [Show full text]