Titanium deposits in Norway

NGU-BULL436 ,2000-PAGE27

An overview of titanium deposits in Norway

AREKORNELlUSS EN,SUZANNEA.McENROE,LARSPETTERNILSSON,HENRIKSCHIELLERUp, HAvARD GAUTNEB, GURLIB.MEYER&LEIFROGERST0RSETH

Korneliu ssen, A.,McEnroe, S. A.,Nilsson,L.P.,Schiellerup ,H.,Gautn eb,H.,Meyer,G.B.&Sterse t h,L.R.2000: An overviewof titaniumdepo sitsin Norw ay.Norgesgeolog iske utidersekelse Bulletin436,27-38

Tit anium depositsin No rway are of threemajortyp es:igneous,metasomati c and met amor phi c.Theigneou sdeposits arecomposed of ilmenite,magn etite and apatiteinvarious proportion s and occur in geological provincesof different ages,andsome have ametamor phi c overprint.TheothermajorTiore-type istherutile-bearingeclo gites in weste rn Norw aythat form ed during the Caledo nian high-p ressuremetamor phism ofpredomin antl yProt erozoic basic igneous rocks.Thethird Tiore-ty pe istheProterozo icrutile-bearing, scapolit isedandalbitised rocksinthe Bambl eregionofSout h Norway.

Norw egianTi mineral resour ces arelarge.TheEgersund provinc einsout hern most Norway isby farthe most significant. ThisprovinceincludestheTellnesilmenitedepo sit which isin operation , aswellaslarge volumesof other low-gradei1menite ores. The annual i1meniteprodu cti onat Tellnes,-55 0,000t.ilmenite,is6-7%ofthetotalmine productionofTi mineralsin the world, andTellnes alo ne has approxi mately12%of the world'sresourcesofilmenite.

Mineralogyisthe overall fact orinf luencing the economic signif icanceof Tideposits,defining thequalityof theTi min eralproductthatcan beproduc ed.Grainsize,mineralintergrowths and mineral chemist ryare areflecti on ofthe geolog icalenviro nmentandlatercondit ionsof the ore-formingprocess.Dueto sig nif icantvariationingeologica l sett ings, Norw egianFe-Tidepo sits show alargerang ein mineralog icalsignat ures.

AreKorn eliussen, Suza n neMcEn roe, LarsPetterNilsson ,Hav ar dGautneb,GurliB.Meyer, Geol og ical SurveyofNorway, N-749 1 Trondh eim ,Norway.

Henrik Schiellerup, Dept.ofGeology and MineralResourcesEngineering,Nor w egianUniversity ofScienceandTechnology (NTNU), N-7034 Trondheim ,Norway .

LeifRoger Ste rseth, Sundgt.10 1, N-5500Haugesund,Norway.

Fig.1.Simp lifiedgeologicalmapofNorway wit h Ti/Fe-Tiprovin ces and depo sits.

Introduction

Norw ayhas alon g tradition in ilmenit e mining, sta rt ing as early as1785 in the Egersund area (Rogaland anort hosite province)insout hwestern Norw ay (Figs.1&2) whereilme n- iteore wasmined as iro nore.For anexcellentoverview see Krauseet al.(1985) .The element Ti was first isol atedin178 9 , but itwasmorethan a cent urybefo re itcould beutil ised on theindustrial scale. Duringthe second half of the19t hcen- tur y,minin g of ilmenite ore bodies in theEgersund area,and also fart her sout heast in the Sokndalarea,com me nced as ironoremin in g,with Blafjellasthe most importantdeposit.

Befo re theturn ofthecentu ry the very large ilmenite ore reserves wit hin the Storgange n ilmenite nori te body were known(e.g.Vogt1887,18 9 2,Kolderup18 9 6 ).Afterabout ten years of pioneering research on utilising the Ticonte nts of theilmenite,the chemistsDrs. P.Farup and G.Jebsen suc- ceeded in 191 6 indevelo pi ng anind ustria l meth odfor the produ ct ion ofa white Ti0₂pigm ent, known today as thesul- phate process (Jonsson 1992). In orde r to utilisethe new meth od and thepatent staken out for it, the com pany Tit ani a A/Sin 191 7 started mini ngthe Sto rgangendeposit.Mining here conti n ued until19 6 5whenall the produc tionwastrans- ferred to the open-pi t ope rat io n at the nearby Tell nes deposit where reg ular mining thenhad already beengoing on forfive years.At present,Telln eshas an ann ualprod uction ofap proxima te ly55 0,0 0 0t. ilme nite.TheNor wegi anTislag produ cer,TinfosTit anium and Iron (TTI), is prod ucing Tislag based on ilme nitefromTell nesaswell asim port ed ilmenite.

Titanium deposits in Norway

Bergen province

Ragaland anorthosite province

~Permian,Osloig neous province

c=JDevon ian sedimen tary basins

c=JCaledo nian Nappe Com plexes

c=JNeoproterozoicarenites

C2JPrecambriansupracrustals/ Caledonised

CZl6~~~~~~::~^gneisscomp lexes/

• Ti/Fe-Tideposit

"?"

NGU-BULL436,2 0 00 -PAGE28 AREKORNELlUSSEN,5UZANNEA. McENROE,LARS PETTERNILSSON,HENRIK SCHIELLERUP, HAvARD GAUTNEB,GURUB.MEYERsLEIFROGER ST0RSETH

Fig. 2.Simplified geolog icalmap andilmenite orebod ies in theRog aland anorthosi teprovince.S=Storgangen ilmenit e deposit,B=BIMjellilmen- itedeposit.BKSK = rock unitsbelo nging to theBj erkreim-So kndal intru- sion.

Fig.3.Compositionof oxidemineralsinthe system FeO-Fep 3 -Ti0_2.

Thedashed linesbetweenilmenit e and magnetite indi cate comm on ge- ological coexistenceat relatively low temperature s,in whichmagne tite commonlycontainsilmen ite lamellae.Such intergrow thsareformedby the oxidationof magnetite-ulvospinelfollowed by oxidation-exsolut ion ofilmenite. Sourcecould notbelocated.

u=hcrnatite Y=(rnaghcrnitc)

FeO

Key

• coexistingpairs al sooec coe xisting: pairsat(,()(Yeandsame

ooxidationstate as•

• ~~~~:~~gs~~rs~~C^andhigher

~ ::~~:~:gs~~rs~~C^andhigher

FeO.

magnetite

TiO

rutile (anatase,brookite)

Fe.0 wii stite

FeTiO

ferropseudobrookite

FeO

N

A

10 km Gneiss

Ano rt hos ite Jotunite

Mangerite (BKS K) Nor lte(BKS K) Leuconorite Cha rn ock ite Fe-T i deposit

o o o o o o

o

More than 300 Ti/Fe-Tidepositsand minor occurrences are regi stered in Norway. Most occur in distinct geolog ical provinces(Fig. 1).It is our opini on that Norway haslarge resourcesof Tithat areinsuffici ently investi gated,and that som e of theseresources might be of sufficientqualityfor the Ti pigme ntindust ryin the future.

The purpose of this paper is to summarisegeolog ical informati on on Tiprovinces andindi vidual deposits in Nor- way. Rut ile resourcesin Norwayarereviewed in a companion paper in this vol ume byKorneliussen etal.(2000).

RQ..·

maU ria/, :

LpKrflJ~J

itme ni te:

PiKm ,"'1 production process:

Ch lorin ata ble materials Su lp h atablemat erials

Products: TiO.pis:;mf'n l

Fig.4.Pathsfrom titan iumrawmaterialstoprod uct s(modified fromDor- mann1993).

Fig .S.Schematicplotof the3majorcategoriesoftitanium mineralprod - ucts;i1menite,titanium slagand rutile,and theirapproximate market price.Thereisadistinctrelatio nshipbetween marketprice and quality, in this figureillustr ated byTi0₂cont ent.However,a complicatedsetof qualityrequirements,as outl inedbyDormann(1993),hasinfluence on the raw-material/market pricerelationships.Ironis animportant eo- productin titan iumslag production.UGS:Upgradedslag(producedby QIT,Canada).

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Ti-slag 4000

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0 2000

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1000 0

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Titanium raw materials and the titani- um ind ust ry

Titan ium isthe ninth most common element in the Eart h's crust,averaging0.9%Ti (Turekian 1977).Itis presentin rocks as oxideand silicate minerals. Oxidemineralsinthesystem FeO-Fe203 -Ti02are shown in Fig.3.Ilmenite and rutile are theprimary raw materials for Tiin the world. Force(1991) divided Ti depositsinto five major classes:igneous,metamor- phic,hydrothermal,sedimentary andweat hered.At present, the igneous, sedimentary and weat hered types are of most economic interest.Australia,South Africaand Canada are the sourcesof approximately80%of thetotalmineproduction ofTi mineralsin theworld,while Norway is producing-5%, asilmenite. The worl dresources ofTi minerals areverylarge, although the know nresources of high- qualityilmenite and rutileareprobably limited.

Some relat ionsh ips between Ti raw mat erials and their products are shown in Figs.4and 5.The term ilm enite,as used by the Ti indust ry,covers both hard-rock ilmenite, con- taining variableproportionsof exsolvedhematite,lowering the Ti02content, and sand ilmenit e enriched in Ti02 by weathering processes.Commercial ilmenite containsfrom 44 to 70%Ti02, whileweathered and heavily altered ilmenite

AREKORNEUUSSEN,SUZANNEA.McENROE,LARS PE7TERNILSSON,HENRIKSCHIELLERUP, HAvARDGAUTNEB,GURUB.MEYER&LEIFROGER ST0RSETH

NGU- BULL436, 2000- PAGE29

Tellnes

Fig. 6.Comparisonofapproximat eTi0₂contents in differe nt titani um oretyp es.Theexamplesusedinthisdiagramare:average crust (1.4%

Ti0_2;Turekian 1977);ilmenite and rut ile sand(Force1991);Tellnes(Nor- wegian hard-rockilmenite minein operation,Krauseetal.1985);Kodal (Norwegi an hard-rock apatite-ilmenite deposit, Lindberg 1985); and Engebofj ellet(Norwegianrutile-bearingeclogitedeposit,Korneliussen etal.2000).

has> 70%Ti0₂and is traded asleucoxene.In comparison , stoi chiome t ricilme ni te cont ains 52.7%Ti0₂•At present, wit h the except ion of arelat ively sma ll rutile hard-roc kmining operation in China,rutileisexclu sivelyobtained from sand deposits,wh ile hard-rock ilmenit eis activelymined in Can- ada and Norway.Titanium slag isan inte rmedia te product madefrom ilmenit e,usedforTipigment production.In theTi slag production process, the iron oxid es are reduced to metallic iron, thereby producing a TiOrrichslag and high purity iron.

The sulphate and chloride processesare used in the Ti industry torecover Ti.ln thesulphate process,i1meniteandTi slagareleached with sulphuricacid.In the chloride process, Ti0₂pigmentand Ti metalare producedfrom rutile,Ti slag and some Ti0₂-rich sand ilmenit es,via aTiCl₄stage at high temperatu res.Upgraded ilm enite,in theform of chlo rinate- ble slagand synthetic rutile,hasbecome an attractive raw material for the Ti0_2-pigment producers.Ninety-threeper- cent of theworld' s consumptionofTi isasTi0₂pigment used mainly in paint s,paper and plastics.Other usesof Ti are in welding rods,and forTi metalinaeroplane construction,heat exchangers and desalin ati on water plants,and avariety of otherapplications.

Quality requirementsim poseseve re restrictions on the Ti raw materials,as pointe dout byDorm ann(1993).Ingeneral, thereisa tende ncy for ilmeniteand Ti slag with low MgOand Cr tobe increasingly more at t ract ive relative to rawmaterials containinghigh MgOand/or Cr.InTiOr pigment production, ilme ni te usedin the chloride process must havelessthan1.5

%MgO.Chrom ium is a waste prob lemfor thesulphate proc- ess, pigment producers;thelessCr in therawmaterialthe better.Similarly,rutilewith alow U content « 10 pp m) is more att ract ive forthe chl oride- p rocess,TiOrpigm ent pro- ducers.These compo sitionallim it at ion s areduetoenviron- mental restriction s.

Miner alogyis essentialfor themineab ilityof Ti deposits.

Insand depositsthe Timinerals areliberated bynature,and theminingcan be doneon low-grade sands if theTi mineral

is of a sufficiently high-quality. H igh quality sands with

1%rutile areecono mic and ilmenite sand dep ositsmay be mined atapproximate ly5%ilm enite.In ilme nite hard-rock deposits, however,the orehastobemined,crushedand the ilmenite separate dout by anexpensive separation process;

therefor e ore-grade requirements will be high .The signifi- cantdiff erencesbetw eenmajorTi ore-typesin termsof Ti0₂ conte ntisillust ratedin Fig. 6.For manysand-d epo sitopera- tion s,by-p rodu ctminerals suchasmonazite andzircon play aneconomi cally significantrol e.

Titanium resources in Norway

Norw egi anTiresourcesaresum marisedinTable1and Figs.

7 & 8.Theigneousdepositshave ilme nite±magnetite±apa- tite in variou s proportion s.These deposits are associated with many types of mafic intrusions in several geol og ical provinces(Fig.1).Themajor Norwegianilmeniteprovinceis theRogalandanorthositeprovince insout hern Norw ay(Fig.

2). Thisprovince containsa largevariety ofilme nite-bearing rocks,and deposit sranging from massive orestolarg e, low- grade min eralisati ons.The most import ant deposit in this region istheworld-classTellnesdep ositwit hayearly produc- tionof 550.000t. ilmenite,which is 6-7%of thetotalproduc- tion of ilm enitein the world.TheTellnes orereserve,wit h57 Mt.of contain edTi0₂,represent sroughly12%of the world's reservesof ilmenite.Elsew here in the Egersund province, large volumesof low-gr ade ilmenite- apatite - magnetite oresrepresent aresourc ethatmight becom e ofeconomic importanc e in the future (Nor.geo !. unders.,unpu blished data),alt ho ugh these depositsstill require furt her investiga - tion.

The Kodalapat it e-ilme nite-magnet ite depositin thePer- mian Oslo Rift(Bergsto l 1972,Lindberg 1985) was investi- gated byNorsk Hydro in the1970's as anapatitedepositwith ilmenit e and magneti te as possible by-prod ucts. Proven reserves are 35 Mt.of massive orewit h 17% apatite, 40%

titaniferousmagnet ite and 8%ilmenite.Anad di t io nal35Mt.

of dissem inatedoreis regardedas a reserve incase of open- pitmini ng(Lindberg 1985).

In theSeilandalkaline provinc e in northernmostNorw ay, larg e volumes of ilme ni te ± apati te in pyroxen it ic rocks (Robin s1985)repr esenta mineralresourc e, alt ho ug hpoorly investi gat ed.Other dep ositsof magmaticilmeniteare,wit ha few excepti ons,main ly deposit s of titaniferou s magnetit e wit h subordinate ilmenite. Themagn etitein thesedepositsis commonly enr iched in vanadium, for examplein the Rod- sand deposit in the More region (Sanet ra 1985) that was mined from 1891to 1981 forvanad iferou s magnet it e wit h the by-p rodu ct ilmenite for use in coalseparat ion . Proven reservesof vanadiferousmagnetite-ilmenit eore in theRod- sand areaare 11 Mt.,wit h additional resourcesof 120 Mt.

(Korne liussenetal. 1985).Howev er, onlyapproximately10% ofthistonn age isi1menit e.Anoth er significant vanad iferous magnetite-ilmen ite deposit is Selvaq in the Lofoten-Vest- eralen province containing an identified resou rce of 44 Mt.

ore wit h an additional possibl eore est imate d to be more than 50 Mt. (Priesema nn&Krause 1985).Tw elveto fourteen percentof this tonn age isilme nite.

Enge bo- fjellet Rutile sands Ti0₂contentin titaniumore types

Kodal

Ilmenite sands

18 16 NI 4 0

f=

~ 10 8 6 4 2 0

NGU-BULL436,2000- PAGE30 AREKORNEUUSSEN,SUZANN EA.McENROE,LARSPETTER NILSSON,HENRIKSCHIELLERUP, HAvARD GAUTNEB,GURUB. MEYER&LEIFROGER SmRSETH

Table 1. Titaniumresourc esin No rw ay.Reservesare orein relation toa mine inop era tion(Tell nes).ld entifiedresourcesareproven sub-economicores. Possibleresources areiden t ifi ed oresthatare poorlyinvestig ated.

Resources (mil l.t.TiO,)

Ti-p rovi nceIregion Type or deposit ^{~Iaj or} Role of

Reserve Identifi ed Possible

Comments

Age deposit titanium resource resource

Bamble -Arendal I1m- ~ lt(V) igneous 1200 - 1250 eo-prod . <1.5%~igOinilm

Rutile mctasornatic 1180 Odegard mainprod. 0.5 >30ppmUinrutilc

Rogalandanrth. prov, I1m igneous 925 Tellnes mainprod. 57 38 3-4%~lg0in ilm

I1m. igneous 930 Sto rgangcn mainprod.

I1m-Ap-Mt igneou s 932 eo-prod, lOO <2.5%~l g0inilm

Bcrgcn I1m-~ lt igneous 950 eo-prod. <1.5 %~lg0inilm

Rutile metamorphic 400 Husebo mainprod. 0.5

Sunnfjord Ilm-Mt igneous 1200 eo-prod. <1.5%~lgOinilm

Rutile metamorphic 400 Engebofj. mainprod. 16 10 <IppmL:inrutile

Rutile metamorphic 400 mainprod. 20 <IppmUinrutile

More Mt(V)-I1m igneous 1700 by-prod. <1.5%~lgOin ilm

Rutile metamorphic 400 mainprod. 10 <1ppmUin rutile

Lofoten- Vestcr len Mt(V)-I1m igneous 1900 by-prod. 1.5-3.0%MgOinilm

Seiland I1m-Ap igneou s 500 eo-prod , 10

Otherdeposits Ap-Ilrn-Mt igneous 270 Kodal by-prod. <1.5%~lgOini1m

60 -er

50 Roga la nd anor thosi tc province

Q '

i-:

~ ³⁰

Tell" es 20

IQ

Sunnlj or d

(rutile)

Engebn - jjellet

\

Reserve

o

o

relate d to Enqebefjell et andot her eclogite sin the area are significant,though further investigationsare needed to fully quantifythe rutile ore.TheEnqebefjellet depositrepresent s alargeproport ion of theworld's resou rces of rutile .

A third deposit category is rutileassociatedwithProtero- zoic metasomatised gabbros in the form of rutile-bearing albititesandscapoli te rocks intheBamb le-Arendal regions of sout hernNorway.Of the known rutile deposits in thisprov- ince,the 0degard rutile-bearing scapolite-hornblende rock (seeSandey1996,and references therein),called edeqardite byBroqq er(1934), isthelargestknowndeposit intheregion.

Thisdeposit probably contains more than 50 mill iontons of ore with 2-4%rutile(Korneliussen &Furuhaug 1993).

Fig.7.Titan iumreserves and reso urcesinFe-Tiprovincesin Norway.

The othermajor Ti ore-type inNorway is rutile-bearing eclogi te found mainlyin West Norway (Fig.1).Eclogitesin the Sunnfjord regi on havebeen ext ensively investi gated, lead- ing to the documentation ofaworld classrut ileresourcein the Enqebofjell deposit. The identified resource at Enge- befjel let is400 Mt . of3-5%rutileore(McLimansetal. 1999, Korneliuss en et al. 1999, 2000).Addition al rutile resour ces

IImenite and titaniferous magnetite provinces in Norway

The Rogaland anorthositeprovince,also calledthe'Farsund - Egersundigneous province'or the'Sout h Rogalandigneous province', comprises large massif-type anorthosites and associated norit ic, jotuni ti c, mangeritic and charnockitic intrusions(Duchesne et al. 1987b).It was emplacedin a Mid- dle Proterozoic, migmatised,metamorphic terrane atinter-

Ilme nite production 1998

World total:4.9:vlt.TiO,

Other countries

Canada (16 %)

llmen itereserves

Wor ld total:405i\lt.TiO,

Som-a)' (14%)

South Africa (15%)

IImenitc resources

World reserve base:538i\lt. TiO,

South Africa (12%)

Sorn·a~·

(7%)

Fig.8.Wor ld ilme n ite mineprod uc- tion, reserves and reso urces,based on J.M. Gambogi, U.s. Geological Surve y Mineral Commod it y Summa- ries,Jan.1999,with modi fi eddat a for Norway(Tell nes) in accordancewith Table 1 and Fig. 7.

AREKORNELlUSSEN, SUZANNEA.McENROE,LARSPETTERNILSSON,HENRIK SCHIELLER UP, HAvARD GAUTNEB, GURLIB.MEYERsLEIF ROGER ST0 RSETH

NGU-BU LL 436,2000-PAGE31

medi ate crusta l levels. Maj orplutoni sm,includin gform ati on of the ano rt hosites,took place between 932 and 920 Ma (Scharer et al. 1996).Ti-Fedeposit s are widespread in the provin ce,principally as ilme nite-mag net it e rich cum ulates, or as ilme nite-magn etiterich dykes.Thereis a widevariety in chemi cal charact eristics and mineral textu res in these deposit s.

TheBj erkreim-Soknd alintrusive comp lex(Fig. 2)is apart of theRogaland anort hosite provin ce withanort hosites, leu- cono rites,troct olites, norites,gab bro nor ites,jotun it es and mang erit es deriv ed through crystallisat io n from a jot unitic parenta l magm a(Duchesne etal.1987a,Wilson etal. 1996, Robi nset al. 1997).It conta ins Fe-Ti rich,noritic and gab- brono rit iccum ulates thathavebeenmined ona smallscale atseverallocation sinits sout hernextension.Theoxide com- posit io ns vary syste matica lly wit h host-rock mineralogy (Duchesne 1972,Wilsonetal. 1996).

The most prominent depo sitis at Telln es(Fig. 9), whic h conta ins mor ethan 300million ton s oforeaveraging 18%

Ti0₂(Krause etal.1985).It isrelated to apost -deform ati on noriti cdyke,havin gan uncertain genet ic relation ship wit ha latejotunitic/mang erit icdyke syste m(Wilma rt etal. 1989).

The BIMjel1ilmenite ores are related to noriti c pegm atite dykeswit hin the Ana-Siraanor t hosite. Severalminorilmen- ite-rlchdykeshavebeenmined ona sma llscalein the past.

The com positions ofthesedykesgenerallyrange from bimin- eralic plagioclase-ilmeniterocks,to locallyoxid e-richnorit es, to'p ure' ilmenititedykes.The layeredStorgang enintrusion wit h Fe-Tlrich noriticcumulates was em placedas a sill in the Ana-Sira anort hosite and was subsequent ly deformed

o

n

rz::J

o

o

o

o

Fig.9.Geologicalmap of the southeastern part(Sokndalarea) of the Rogalandanort hositeprovince.ModifiedfromKrause &Ped all(1980).

throughtherelat ivemotion sof the ano rt hosi teand the Bjer- kreim- Soknda l intrusion (Schie llerup 1996).The Sto rga nge n int rusion was mined from 1916 to 1964. The ide nti f ied remaini ng orereserve is 60Mt.orewit h 17-1 8%Ti0₂(Krause et al. 1985). Bet we en the Egersund -Ogn a and Haland anort hos ites thereis a zoneafewhundredmetr es widewith leuc on or it ic ort ho gneissanda spect rum ofot her gneisses.

Thisunit includesseveral rew ork ed intr usive bodie s(Koldal- Kydla nd area, Fig. 2) bet w eenthetw o massif ano rt hosites and they were subseq uent ly deform ed by their relative movem ent s.llm enitedepositsin this zonearelikelytorepre- sent fragm ented and reworkedoxide- richcumulates;oxide com posit io nsvary syste mat ically from east to west (Duch- esne 1999).

The Bam ble- Arendal Fe-Tipro vin ce,alsocalled the Bamble Sector of the Balti c Shie ld, conta ins rocks that have been affecte d byboththeGoth ian(c.1500-1750 Ma) andtheSve- cono rwe gia n(990 - 1250 Ma) orogenies(e.g.,Sta rme r1991, Kullerud &Dahlgren1993).Deposits of ilmenite and V-r ich magn etite are found asband s and lensesin themet agabb ros and amp hibolites that are possibly related to magm ati sm early in the Sveco no rweg ianoroge ny.Thismagm ati sm was followed by aperiod wit h exte nsive hydr ot herm al activi ty that caused themet asom ati c altera tio nof basic rocksinto scapolite rocksand albit ites.At 0dega rden, gabbros and am p hiboliteswere metasomatically alte red to a rut ile-bea r- ingscapo lite- horn b lende rock callededeqardi te byBrag ger (1934).During thisprocess,Cl-rich fluid sleached ironfrom ilmenitewhi le Ti,whichisfairl yimmobil e,wasincor porated intorutile.The classic edeqardlte localit y is a1.5 km-lo ngand 100-150 m-w idezone surro unded bymet agabb ro/am phibo- lite (Bragge r 1934,Lieftin k etal. 1993, Korne liussen& Furu- haug1993,Sande y1996).Theedeqardite was alte redto albi- tite along fractures by later metasom ati c fluid s. Many occurrences of rutile-b earing albit ites are known in the 0degarden - Kragero regi on (Bragge r 1934, Green 1956, Bugge1965).

TheBerg enFe-Tipro vin ce.The Berge ndist rict contains a tecton ostratigraphic unit comp rising Precam brian anort hosit ic, jotuniticand mang eritic rocks wit havarietyof ilmenite - magn et it e dep osits. Part sof the regi on experi- encedCaledoni anhigh-pressuremetam orph ism andeclog i- tisation, such as the Husebelocalit y at Hol sney whichcon- tains 2-5 %rutile (Korne liussenetal.1991).

The Sunnfjo rd Fe-Tiprovinceis apart of theWestern Gneiss Regi on, com posed of Proterozoic mafic and felsic igneous rock sthat werest ronglyaffec te d bytheCaledon ian orogeny (see Korneliussen etal. 2000).Tw otyp es ofTi depositsoccur in thisregion:magm ati cilmenite -magn etite depositsassoci- ate d with Proterozoic mafic int rusions,and rutile-bearing Caledon ian eclogitic roc ks.Therutile-b earin g eclogites are Proterozo icbasicrocksthat were transform ed into eclogi te during Caledonianhigh -pr essuremet amorphi sm atap proxi- mately400 Ma.During thisprocess,ilmenitein the prot olith brokedown, wit h theFeentering garnetand Ti intorutile.In thisprocess,large volumesof ilmenit e-b earing mafic rocks were transform edinto rutile-bearing eclogitic rocks wit h the same Ti0₂ content, but of much more econo mic interest

NGU-BULL436,2000-PAGE32 AREKORNEUUSSEN,SUZANNEA.McENROE,LARSPEITER NILSSON,HENRIKSCHIELLERUP, HAvARD GAUTNEB,GURU B.MEYERs LEIFROGER ST0RSETH

since the price of rutileis much higher than that of ilmenite.

Froma mineral resource perspective,the ilmenite deposits in the regionare of only minor int erest, while the rutile-bearing eclogitesrep resentamajo r mineralresource,part icularly the Engeb ofj elldeposit.

The More Fe-Ti provinceis, like the Sunnfjord province,a part of the WesternGneiss Regionof southern Norway, with a large variety of Proterozoic rocks affected by the Caledo- nian orogeny.Magnetite- ilmenite ores(Geis 1971)are found in certainsuitesof metagabbro and amphibolite.Rutile-bear- ingeclogi tesarecommon in partsof this province.TheRod - sand deposits (Sanetra 1985) wereamajor sourceofFe-Ti-V ore inNorway for80 years,unti lmining ceased in 1981.

The Lofoten - vesteralen Fe-Ti province.Massive and dis- seminatedFe-Ti deposits occur in gabbros and anorthosites that belong to a 1900 Ma suite of intrusions emplaced into Early Proterozoic sup racrustals and Archaean gneisses. A maj orFe-Ti depositis the layeredSelvaqgabbroic intrusion (Priesemann &Krause 1985).This int rusion contains cumu - latelayers of magnetit e -ilmenit e.Anoverview of thegeol- ogy ofthis province hasbeen givenby Griffin et al. (1978).

Th e Seiland Fe-Tiprovince.The SeilandIgneous Province in northern Norway consists of very large volumes of mafic and ultramafic rocks. The province contains large, low-grade deposits of Fe-Tioxides within intrusions of gabbronorite, oli- vine gabbro and horn bl ende c1inopyroxenite(Robins1985).

RecentresuItsofisotopicdata suggestt hat much ofthemag- matism took placein connect ion wit h Riphean to Mid dl e Camb rian intracontin entalrifting (Robins 1996).

Isolated deposits.Scat tered occurrences of Fe-Tideposit s occur outside the main Fe-Ti geological provinces. Most of these are of Proterozoic age, an exception being the Kodal deposit (Lindberg 1985)in the Perm ianOslo Igneous Prov- ince.This oreisbelievedtohave formed either from a Fe-Ti oxide andapat ite- rich magm agenerated by liqui d immisci- bility (Berqstol 1972) or by cumulus processes relate d to a monzonit ic magma (Lindberg 1985).

Oxide mineralogy

General oxide mineralogy

The mainTi-bearing minerals ofinterest, ilmenite (FeTi0₃).

hemo-il menit e (FeTi03 wit hexte nsive Fep 3 solidsolut ion, now ilmenitewithhemat ite exsolutionlamellae),rutile(Ti02) and titanomagnetite (Fe2Ti04-Fe304).are all in the system FeO-Fe20 3-Ti02 (Fig.3).There is a large compositional range in ilmenites in intrusive igneous rocks,because ilmenite is formed either by direct crystallisation from a melt, or as a produ ct ofoxidation-exsolutionfrom titanomagnetite(Frost

& Lindsley 1991).At low temp eratu res and unde rstrongly oxidi sing conditions ilmenit e alters to rut ile plushem atit e.

IImenite and magnetiteoccur widely in low- to hig h-grade metamorphic rocks.Rutile occursmost commonly in three metamorphic settings,in all of which FeO available for the format ion ofilmeniteis lacking:(a) in rocks dominated by sul- phid es or hematite. (b) in rocks that are low in FeO due to hydrot hermal alter at ion,such asinthe Bamblearea ofSout h Norway. (c)inhigh-pressuremetam orp hic rockswhere FeOis

strongly fractionated into silicates,such asin the eclogite province of West Norway.

In Norway, ilmenite is found in both igneous and meta- morphic settings as illustrated by the examples shown in Fig.10.The selected samples represent a variety of geo- graphic locations and petrogenetic histories and highlight the variation in oxidemineralogy.The largest hemo-ilmen ite andilmenit e± magnetitedepositsare those associated with anorthosite bodies in the Rogaland region . More detailed descriptions of ilmenite from Tellnes, as well as elsewhere in the Rogaland region, are presented in a companion paper in th is volume (McEnroe et al.2000) and in Duchesne(1972, 1999). The magmatic ores in this region vary intheir average ilmenite, hemo-ilmenite and magnetite contents and show significant textural variations.

The Tellnes deposit in Rogaland,southern Norway,con- tains hemo-ilmen iteand minor magnetite.The ilmenite host has abundant hematite exsolution lamellae parallelto{OOOl}

as shown in Fig. lOa. Multiplegenerations of hematite exso- lutiondow nto themicron scale are observed,and,based on measured magnetic properties(McEnroe et al. 1996,McEn- roe1997),it appears that generation of exsolution lamellae continued down to the nanometre scale (Harrison et al.

1998). Minor aluminous spinels are common exsolut ion products.Directly surrounding the spinelthere is a zone free of hematite exsolution. When hemo-ilmeniteand magnetite are in contact(Fig. l Ob),a symplectiteof magnetite,ilmenite and spinel is formed by re-equilibration during cooling in which Fe³+ in the ilmenite was exchanged for Fe²+in the magnetite.The portion of the ilmenite grain thatis in direct contact with magnetite is free of hematite exsolution due to the diffusional loss of Fe3_+.In the magnetite-rich cumulate rocks from other localitiesin the Sokndal regionthe magnet- ite generally has {111} oxidation-exsolution lamellae of i1menite as well as lame llae of spinel. Spinel-magnetite- ilmenit e symplectitesare common where ilmenite-magnet- ite grains are in contact(Fig. lOb).Discrete ilmenite grains in the magnetite-rich rocks are free of hematite lamellae. Fig.

10c shows a typical titanomagnetite from the Kodaldeposit in larvikite of the Permian Oslo rift.This deposit is richin mag- netite, ilmenite and apatite.The titanomagnetitecommonly has{111} lamellae of ilmenite and minute spinel parallel to {lOO}. Discret e i1menite and euhedral apatite crystals are present in most samples.

In the Lofoten - Vesteralen province the Proterozoic Eid et-Hovdenlayered mafic intrusion hosts the SelvaqFe-Ti- V deposit(Priesemann&Krause 1985).The titanomagnetite grains commonly have{111} oxidation -exsolution lamellae of ilmenite(Fig 1Od).The first generation of ilmenite lamellae commonly enclose spinel. Multiple generations of spinel exsolution parallel to {lOO} are also presentthroughout the titanomagnetite grains. The variety of microstructures reported from the deposit, trellis, sandwich and composite lamellae,and lit-par-Iittextures may well beindicat ive of var- iations in the oxidation and cooling history in the layered intrusion.

Two examples of metamorphosed Fe-Tiore deposits are shown in Fig.10.TheRedsandore, host ed by anamphibolite

AREKORNEUUSSEN, SUZANNEA.McENROE, LARS PETTER NILSSON, HENRIK SCHIELLERUP, HAvARD GAUTNEB,GURU B.MEYER&LEIFROGER ST0RSETH

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NGU-BULL436, 2000-PAGE

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Fig.10.(A) IImenite(darkbrown)with very fine hematiteexsolutionlamellae(light grey),Tellnes ilmenite norite ore. (B) Ilmenite withspinelsym plect ite at themagn etit e co ntact, and magn etit ewith lamellaeof ilmeniteandspinel. llmenite-magnet it e bearing norite from theSokndal area.(C)Titanom ag- netit e (lightgrey) wit h closelyspacedilme nite lamellae andabundant euhed ralapatite (dark grey) cryst als. Kodallarvikit e (monzonite)hoste dap-rnt- ilm/P-Fe-Tidepositin thePermia nalkaline OsloRift . (D) Tit anom agn etite (light grey)withseveral generation sof fineand very fine spinel exsolut ion lamellae (black) plusbroaderi1menitelamell ae,all following crystallograph icdirectionsin the host magnetite.SelvagFe-Ti-Vdepositin theProterozoic, Eidet-Hovden ,layeredmafic intrusion,l.ofoten-VesteralenFe -Ti province.(E) Typical Redsand ore:magnetite (grey) with minutespinel exsolution lam ellae (rig ht),abundantsulp hides (white) and hemo -i1menitegraduallypassingintoilmeno-hematite aw ay from the magnetite contact.Redsand tit anom agn etit e-iim enit edeposit,hosted ina st rong ly deform ed andam phibo litised Palaeoproterozoic gabbro,MoreFe-Tiprovince. (F) Prismatic inclusio nsof ilme nitein magn etite.Reramagnetit e-ilm enit e occurrence, hosted inabasic complexwestof Porsgrunn,Bamble -ArendalFe-Tiprovi nce (Kongsberg-Bam ble, Mid Prot erozoic,high-gr ade shear belt).The ore isamong the most vanadiumrich in Norwaywith up to 1.5 wt.%V₂0₃in magn et - ite.