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Falconbridge Sul203- 72- 16 SulfidmalmA/S

Tittel Sulphide prospecting in the Reinfiord area.

Forfatter Dato Bedrift H A Rosenqvist Des. 1972 Sulfidmalm A/S

Kommune Fylke Bergdistrikt 1:50 000kartblad 1: 250 000 kartblad Knenangen Troms 1735217353 Hamm erfest

Fagområde Dokument type Forekomster Geologi Rapport Reinfjord area: S of Isdalen

Olderfiord area: Spitsnes Råstotttype Emneord Malm/metall Ni Cu Fe S

Sammendrag A/S SULFIDMALM

INTER-OFHCE MEMORANDUM

Date : 24th January, 1973

To : Falconbridge Nikkelverk A/S

cc: M. Clarke, D. R. Lochhead, H. A. Rosenqvist, R. B. Band, A. Sturt From : J. B. Gammon Subject :

905-16 Reinf'ord area, N. Troms. (Report No. 203-72-16).

Please find attached Rosenqvist's report on prospecting in the Reinfjord area, N. Troms. Sulphides are encountered along the pyroxenitic border facies of a layered ultrabasic intrusion. The best assay returned was 0.42% Ni, 0.32% Cu, 1.6% S. Sulphide enriched horizons were also found in a rythmically layered norite intrusion from which the best assay result was 0.31% Ni, 0.30% Cu, 1.8% S. Further follow up work will be carried out during the course of "Operation Phoenix" in 1973. • FOR FALCONRRjDCE flIRKELVERK A/S • A/S SULEIEMALR PROJECT 905-13

SULENILE ROSEECTINO IN THE

RE1NYO,(.2RPAREA fl.TRCNS.

DECENRRR 1972

by

H . A. ROSENUTST INTRODUCTION.

The report deals with sulphideprospecting,carriedout in two selectedtarget areas within the district, N. . This districtforms the SW part of the mafic-ultramaficprovinceof Vest-Finnmark,the general target for project 905-16. The Reinfjordultramaficcomplex. • The Olderfjordnorite. The geologyand economicpotentialof the first target have been treated in an earlierreport by M. C. Bennett (Sulfidmalmreport202-72-16).

LOCATIONAND ACCESS.

The Reinfjordarea (21°E/70oN)is locatedN of Kvaen- angen fjord, approximatelymidwaybetween the towns Tromsø and Alta. (Fig. 1). The small fishing village of Reinfjordcan be reached by a (more or less) regularboat connectionfrom Jøkelfjord,or by taxi flights. Target A occupiesthe high ground NE of Reinfjord,whereas target B is • exposed in the mountainsW of this fjord. The area is mountaineousand both targets are well exposed. The ultramaficcomplex extendsbeneath the ice cap Langfjordjøkelen,otherwisethe targets are only locallycoveredby snow, small lakes and talus material. More than usuallyrough topography,with steep walls and unstablescrees, creates accessibilityproblems. In simple "hammerprospecting"these are however only time consumingrather than obstructive. -2-

A. REINFJORDULTRAMAFICCOMPLEX.

General.

The ultramaficcomplex consistsessentiallyof layered peridotitesintrudinggarnet gneiss in the S and W, but elsewhereintrudinglayered gabbro (Fig.2). The complex forms a roughly saucer-shapedmass,with lateraldimensionsapprox. 6 x 4 km. A minimum of 1000 m thicknessis exposed. Fig. 3 is a simplifiedpicture of the zoned rock type distributionwithin the ultramaficcomplex,as mapped by M. C. Bennett.

UDZ Upper dunite zone: Dunite and wehrlite. MLZ Middel layered " : Layered clinopyroxenitesand wehrlites. UMZ Upper marginal " : Two-pyroxeneperidotite, felsphaticperidotiteand pyroxenite. LMZ Lower marginal " : Layered olivine-pyroxenites, pyroxeneperidotitesand pyroxenites.

For a detailedgeologicalmap and descriptionit is refered to Bennettsreport (202-72-16). Of particularinterestis a "sulphidephase" occuring within the marginal zones. Prospecting,carriedout during a 9-day trip in July 72, was mainly directed towardsthese zones. Also the centralportionswere prospected,but in a reconnaissancemanner. Later in the season a limitedsection of the sulphidecarryingSE margin (MLZ-UMZ)was mapped as an attemptto outlinethe magnitudeand possiblepattern of sulphidemineralization here. Some reconnaissanceVLF-EMprofileswere also run over this section.

. 1 3

SULPHIDEMINERALIZATION.

(1) LMZ:

This zone was prospectedin upper Kjerringdaland along the steep slopes E of Reinfjord. The rock is a fine- medium grainedpyroxenerich ultramafic,locallyalso slightlyfelsphatic. Small amounts of interstitial po-cp mineralizationcan frequentlybe observed. • Richest found mineralizationassayed: Sample Ni Cu Fe

16 Lo 8 0,15 0,07 8,5 0,2 % 16 Lo 9 0,18 0,16 8,2 0,3 %

(2) UMZ/MLZ:

The boundarybetween these zones are difficultto observe in the field, especiallyon the W-side as pointed out by Bennett.

The area N of Isdalen ice-fallwas prospectedbetween Sneidalenand the peak 1001. (See Bennett'smap). • Only sporadicsulphidegrains were found and the area seems to be without economic interest.

The Isdalen - Storvannet sectionof the marginalzones frequentlycarrie.sainieMinatedsulphides,but in accessoric amounts. The sulphides,po with minor cp, occure inter- stitiallyparticularlywithin pyroxeniticrocks. "Concen- trations"(est. 2-5% of vol.) were observed in small irregularportions,also in localitiesnot marked by Bennett as sulphidebearing.

. 1 4 -4-

A promisingtype of mineralizationwas found at the head of a narrow valley S of Isdalen. Approximately10% of sulphides(po-cp)occure interstitiallydisseminatedin a coarse grainedpyroxenite(samples5 and 50). Being of very modest dimensions(verticalexposure 70x70 cm), this sulphideenrichedportion is economically unsignificantin itself. Neverthelessit gives a clear indicationof what type of enrichmentcould be expected within the ultramaficcomplex. Samples from sulphideenrichedportionswithin the Isdalen - Storvatnetsectionassayed:

Sample Ni Cu

16 Lo 5 b 0,42 0,32 8,7 1,6 % 6 0,24 0,13 10,2 1,0 % "19 (loc.boulder)0,31 0,10 7,9 0,8 % "50 0,36 0,25 9,2 1,5 % "51 0,20 0,11 7,9 0,6 %

- Sulphideenrichedportionsof any importancewere not found along the southernmargins. Irregularand faint disseminationscan be observedat the head of a valley running eastwardsfrom Reinfjord (i.e. southernmostUMZ), whereas the sectionNW of claim point K4 seems to be almost free of sulphides. The layeredolivinepyroxenite (MLZ) in the southernpart of the complex also appearsto be almost sterile. Two faintlydisseminatedportionswere observedand the richest possiblemineralizationsampled:

Sample NiCuFe

16 Lo 16 0,15 0,07 8,5 0,2 % 16 Lo 52 0,27 0,08 15,8 0,2 %

../5 -5-

- Reasonableamountsof sulphidedisseminatedpyroxenites occure along the E margin of the complex. Up to 10 vol. % of sulphidesZpo-cp)were found in pyroxenites adjacentto the intrudedgabbro. This section contains the most wide spread sulphidemineralizationexposed within the ultramaficcomplex. It was therefore selectedfor more detailedinvestigations. (See A-4 below).

UDZ:

This is a rather homogenousdunite frequentlycut by narrow coarse grained mafic dikes. Sulphideswithin this • body are rare. The localityN of Tverrfjorddalenvann, noted by Bennett,carriesa maximum of 1-2 vol. % of pyrrhotite. The mineralizationis here associatedwith a pyroxenebearing olivinerock (wehrlite).

The E mar in of MLZ/UMZ:

Geology andmineralization. A 1600 m long section (N 40 E) of the marginalzone was mapped at 1:1000 scale by F. Engberg (10-16.8.). His main task was to outline the sulphidemineralizedportions. Engbergsmap, also showing sample localitieswith assay results,is enclosed (1-203-72-16). 411 Three main rock types are distinguishedwithinthe area:

Gabbro (16 Lo 62) is a banded fine-mediumgrained anorthositicrock. No sulphideswere observed. Olivinepyroxenite(16 Lo 64) is a layeredultramafic with a characteristicyellowishscraggyweathering surface. It correspondsto Bennett'sMLZ. Sulphide mineralizationonly occures as scatteredsingle grains within this unit. Pyroxenitesin general occupy the ground between (a) and (b). They show clearly intrusivesharp contactsagainstthe gabbro whereas contactsagainst olivinepyroxeniteare gradational. Using the grain size and abundanceof sulphidesas criteria,4 types of pyroxenitewere distinguished.

../6 -6-

Pyroxenite(blue) comparativelyfree of sulphide mineralization. Type sample 16 Lo 63. Mineralizedcoarse grainedpyroxenite(red). Type sample 16 Lo 73. Mineralizedmedium grainedpyroxenite(purpur). Type sample 16 Lo 76. Mineralizedporphyriticpyroxenite(darked). Type sample 16 Lo 98.

Apart from the distributionof these rock types, the map (1-203-72-16)also show the visuallyestimatedsulphide contentswithin them. The sulphides,mainly pyrrhotite with some chalcopyriteand pyrite, always occure inter- stitiallybetween the silicatesor along the cleavage face of pyroxenes. The sulphidedisseminationsare of uneven and discontinuous character,but generallyspeakingthey are more wide spread than in the rest of the margins of Reinfjordultramafic complex. The most wide spread mineralizationoccure within coarse grainedpyroxenite,the largestone being exposed over an 250x40 m area. (300N - 500N). A total of 35 rock samplesfrom the area were assayed for Ni, Cu, Fe and S by XRF (Kristiansandlab.). Keeping in mind that only sulphidecarryingsampleswere assayed,the results are all but promising. (Table 1). Ni/S contentsare marked on the map. The field observation that sulphideenrichmentslightlyhave favouredthe coarse grainedpyroxenite,is confirmedby assay results!

VLF-profiles.

VLF-electromagneticmeasurementswere made along 6 profiles over the mapped section. A Crone Radem instrumentwas used, transmitterat Bordeaux,France (15,1kHz). Observeddip angle data and calculated"Fraservalues" t) are shown on map 2-203-72-16.

3c)FRASER D.C. (1969) Contouringof VLF data: Geophysicsv. 34, p. 958-967.

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Table 1: Assay results, E-margin.

% Ni % Cu % Fe % S NUMBER ARITNM. ARITNM. OF RANGE RANGE RANGE RANGE SAMPLE MEAN MEAN

TOTAL 35 0,05-0,24 0,10 <0,05-0,09 6,3-12 0,19-1,20 0,44

Pyroxenite 2 18 0,05-0,18 0,10 <0,05-0,09 6,7-12 0,19-1,20 0,55

Pyroxenite 3 8 0,05-0,24 0,10 <0,05 6,3-10,4 0,19-0,70 0,40

Pyroxenite 4 5 0,06-0,10 0,08 <0,05 6,5-8,8 0,19-0,31 0,23

:57 -7-

Two clear anomalieson the southernmostprofile D, weakly picked up on E, are not explainedby present field observations. The anomaly zone in NW is most likely related to a tectoniczone, clearlyvisible on aerial photos. The main experiencefrom this VLF-reconnaissanceis that the method was unable to T= the observedsulphide disseminatedbelt. Consideringthe discontinuoustype of mineralization,this might however be achievedby a more systematicand detailedsurvey.

B. THE OLDERFJORDNORITE.

General geology.

The Olderfjordnorite (Fig. 2) is describedby Hooper in 1971 (NGU 269 pp. 148 - 151) as a rythmicallylayeredwell preservedN-S elongatedintrusion.

"Rythmiclayering,due to variableproportionsof the principalmineral phases, labradoriteand orthopyroxene, and locallyemphasizedby variationin grain size and texture,can be mapped accrossthe intrusion. Althoughdisturbedby many small faults,the general assymetricsynformalnature of this structureis well presesved,dipping away from the verticaleastern contact at 60 W, passing through the horizontaland lying at appsoximately20 E againstthe relativelyshallow (30 E) dip of the western contact. Density stratification is observedin many places, but is not universal. Igneous laminationand lineationoccurs in the pyroxenerich layers. The more feldsphaticlayers are largelyrecrystal- lized,but there appears to have been no change in compositionof either the feldsparor the pyroxene during this process. It must be assumedthat recrystal- lizationtook place either at a temperaturevery similar to that of primary crystallization,in the chrystalmush stage or, if later it took place without the availability of water to form hornblende.

../8

-8-

A very slight cryptic layeringhas been detectedby carefulopticalmeasurementof the pyroxeneand plagioclase. The higher temperatureassemblages occure at the top and bottom of the exposed section (Reinfjorddalen),andthe lowest temperatureassem- blage near the middle. The final portion to crystallizeis more feldspathicthan, and locally transgressiveto, earlier layers and containsalmost as much elinopyroxeneas orthopyroxene."

Concerningthe regionalsetting of the Olderfjordnorite, Hooper presents a hypothesisbased on the assumptionthat the adjacentSandland- Middagsfjellgabbro (to the N) and the Andsnespeninsulagabbro (to the NW) all belong to the same originalintrusion (See fig. 2). Accordingto the idea, • the Olderfjordnorite represents "a north-south elongatedfeeder dyke, widening rapidlyupwards to the west to form the conformableAndsnes sheets and with the Sandland- Middagsfjellmass forming the upper part of the intrusion,packed with sedimentaryrafts."

Sulphideprospecting.

Elementaryhammer prospectingfor sulphidemineralization was carriedout by studentsKL/LM during a 10-day trip in July 72. A stronglyweatheredrusty zone - Spitsnesrust belt - was located in the southernmostpart of the area approximately1500 m NW of cape Pilvaag (see red spot on fig. 2). The E-W trendingbelt (est. 300 x 50 m) is exposed 500-600m a.s.l. on the steep and unstablesouthernslope of Spitsnestind. Samples,showing a fine grainedsulphide disseminationin presumablya mafic layer of the norite, • assayed

Sample Ni Cu Fe 16 Lo 31 (loc.bould.) 0,31% 0,30% 18,0% 1,8% " 32 (outcrop) 0,41% 0,15% 17,6% 1,2% 33 0,31% 0,11% 12,8% 0,8%

. . /9

-9-

Except for the Spitsnesrust belt, no significantminerali- zation was found within the norite. Sulphidesare rare, occuringonly as small interstitialgrainsin accessoric amounts, if not totally absent. Two samples,representing the "richest"mineralizationfoundoutside Spitsnesrust belt, were assayed:

Sample Ni Cu Fe

16 Lo 25 0,20 0,08 11,8 0,9 % • ”27 0,18 0,09 12,0 0,5 %

CONCLUSIONS.

A. - As pointed out by Bennett (202-72-16),sulphideminerali- zation of the Reinfjordultramaficcomplex is associated with pyroxeniticrocks along the margins. Observedsulphidesalways occure interstitiallyand in a irregularand discontinuousmanner. Field observationsand assay results indicatethat the mineralizationin generalis without economic interest. • Minor follow up work seems however justifiedby: The mineralizationfoundS of Isdalen. The unexplainedVLF-anomalyat the E-margin.

This work is suggestedto include: Geologicalinvestigationof the "showing"S of Isdalen. (Blastingand mapping). DetailedVLF-EM/Mag.survey over this area S of Isdalen. Field examinationof the VLF-EM anomaly at E-marginby geologicaland systematicVLF-EM/Mag.work.

../10 -1 0- li

B. - Reconnaissanceprospectingofthe Olderfjordnorite showed that it in generalonly containstotally unsignificantaMoUntsof disseminatedsulphides. The "Spitsnesrust belt" suggeststhat sulphide enrichmentoccure. If present in other localities these shouldbe detectedby helicopterreconnaissance (OperationPhoenix1972). The Spitsneslocalityis recommendedfor geological examination,i.e. tracing,samplingand mapping the sulphideenrichedbelt. •

Encl. Fig. 1: Genl. locationmap. " 2: Geologicalmap of the Loppen district. 3: Reinfjordultramaficcomplex. Locationmap. • Map 1-203-72-16 Reinfjordultramaficcomplex. Geology of part of the E-margin. " 2-203-72-16 VLF-EM profiles. Reinfjordultramafic,E-margin. 111 I

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Mapped and compiled by PR Hooper 1961-1968 with 0 Ch710/101 information from D.Lewis ( Andsnes Fig. 9. Geological map of the Loppen dispiet, Wen Finnmark and North Troms, Norway foo.crerep peninsula). C.W.Gronow (Loggiu an0 Silda ) and C. Blackburn Isdol en longljord jekelen

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