The Geology of the Bidjovagge Mining Field, Western Finnmark, Norway

The geology of the Bidjovagge mining field, western Finnmark, Norway

NILS B. HOLLANDER

Hollander, N. B.: The geology of the Bidjovagge mining field, western Finnmark, Norway. Norsk Geologisk Tidsskrift, Vol. 59, pp. 327-336. Oslo 1979. ISSN 0029-196X.

The Cu-mineralizations in Bidjovagge occur in the Caskias-Stuorajaure group which consists of green-, hornblende-, and graphitic schists, greenstones, and plagioclase-carbonate rocks. Amphibolites and diabases of presumably intrusive origin are common. The mineralizations are localized to feis and carbonaceous schist in the limbs of an anticline striking N-S and dipping 15-30" north. The ore minerals are chalcopyrite, pyrite, and pyrrhotite occurring as impregnation and in veins, occasionally with galena, sphalerite, and magnetite. The best ore is C, consisting of three ore bodies with total reserves of approximately 2.3 million ton ores with 1.5% Cu.

N. B. Ho/lander, Saga Petroleum a.s. & co. , P. O. Box 550, N-1301 Sandvika, Norway.

Bidjovagge copper mines are situated on the 1963 KKSU was taken over by NGU, which Caskias mountain 69"17' N, 22°29' E, 700 ma. s.l. continued the investigations in the next three (Fig. l) in Finnmark, north Norway. years resulting in the following estimates of the The mineralizations occur in what is known tonnage of the mineralizations (i. e. Ingvaldsen, as the Caskias-Stuorajaure Group, which in Paulsen & Mathiessen 1966): cludes greenschists, homblendeschists, graphitic schists, greenstones, and plagioclase-carbonate Prov en %Cu Probable rocks. Amphibolites and diabases, which pre reserves reserves sumably re present rocks of intrusive character, (ton) (ton) are common (Holmsen et. al. 1957, Mathiesen A: 302,000 2.10 100,000 1957, 1959, 1967). B: 253,000 1. 83 50,000 What is known of the discovery of the C: 2,065,000 1.84 250,000 mineralization dates back to the late 1940's or D: 360,000 1. 84 200,000 early 1950's when two Lapps found sulphides on Total: 2,980,000 1. 80 600,000 the Caskias mountain. Some rumours, however, indicate that it was known as early as in the In addition 1/2 ppm Au was indicated. 1920's. Whatever the truth, the claims were staked in 1952. Boliden Mining Company, Swe In 1967 A/S Bidjovagge Mining Company was den, started their field work the same year. The formed by AlS Bleikvassli Mining Company. application for a concession was, however, re The plant was completed in 1970. Production jected. started the same year. In 1974 A/S Sydvaranger In 1955 the Norwegian government made an bought A/S Bleikvassli Mining Company and agreement with the owners of the claims, bought thereby also Bidjovagge. A systematic eva1ua the geological and geophysical reports from tion of the mine and prospecting in the surround Boliden, and started investigations. In 1954-1956 ings started in 1974. During 1974-1975 the author Norges geologiske undersØkelse (NGU) made a was in charge of the geological work in the regional geological mapping. From 1956 geologi mining fieldas well as the regional prospecting in ca! mapping, geophysical measurements, geo western Finnmark. chemical sampling, and diamond drilling were Due to the falling prices of copper and small carried out by Kautokeino Kobberfelter Statens production the mine was closed down in mid- UndersØkelser (KKSU), which was specially 1975. formed for prospecting this area. The C mineralization was investigated in 1960-1962 by mining and diamond drilling at 600 m a.s.l. In 328 N. B. Ho/lander NORSK GEOLOGISK TIDSSKRIFT 4 (1979)

Geology rock consisting of hornblende, biotite, quartz, albite-rich plagioclase, carbonate, magnetite and General pyrrhotite, and some chlorite. Aggregates (1.5-. From west to east the rocks around the C-mine 10 mm) of hornblende are common. are carbonate-rich rocks, feis, amphibolite, carbonaceous schist, diabase, alternating feis, Feis. - This name is introduced to describe a and carbonaceous schist locally very rich in felsic, fine grained, massive, metamorphic rock chalcopyrite and pyrite, and finally greenstone consisting of albite, quartz, and calcite. It has a with amphibolite and diabase (Figs. l and 2). diffuse layering and/or heterogeneous bedding These rocks form part of the Caskias-Group with < 5 mm thick bands, white to greyish white, which represents a period of intense and wide grey or redbrown with a grain size of 0. 14l. 3 spread rather basic volcanic activity in the mm. The main mineral is albite, quartz and Karelic geosyncline. The present survey has, calcite occurring in smaller amounts. Horn however, been carried out in much greater detail blende and biotite exist in small quantities. than the earlier ones. Generally, Mathiessen's Muscovite has been found but is rare. Some map (1970) compares well with the present one. times the quartz exists in 1/2 mm lenses. 1/2 mm aggregates of sericite and pyrophyllite (probably secondary after sericite) tale and small zircon Rocks crystals were found in drillhole 1440 S, 915 E, at Carbonate rich rocks. - These have only been 477 m, a.s.l. The feis is locally very rich in found in two outcrops but are recognized in chalcopyrite, pyrite, and pyrrhotite. Magnetite is many cores west and southwest of the C-mine. usually an accessory mineral. Galena and sphal They are diffusely layered, light brown-grey, erite have been found. The feis is sometimes so slightly weathered, fine to medium grained rocks finegrained ( <0.01 mm) that identification of the consisting of dolomitic and ankeritic carbonate minerals in thin sections becomes impossible. minerals with some amphibole. Pyrite occurs as The rock is cut by irregular veins (< 5 cm) filled an accessory mineral in the eastern limestone with calcite and dolomiie, some quartz and (lying around 800 E south of profile 1100 S) albite, with accessory biotite and iddingsite. which is fairly dean. The western carbonate They can locally be very rich in chalcopyrite. rock (situated between 600 and 775 E) is rich in The feis is very similar to the leptites found in hornblende and to some extent also biotite. the Precambrian of northern and middle Swe Locally it contains actinolite and is slightly den. schistose. Carbonaceous schist. - Diffusely bedded to Diabase (metadiabase).- The diabase stretches homogeneously layered, only locally schistose or from profile O in the north to the south and even brecciated, black to greyish black with thin southeast, forming the upper central part as well light grey to greyish white hands. The dark as part of the eastern limb of the big anticline. hands are less than 10 mm thick and the light The upper central part of the fold is filled with ones less than 2 mm. The difference in colours the above mentioned carbonate-rich rock and depends on the relative amounts of light and the diabase. dark minerals. The rock is very fine grained It is massive greenish black, fine to medium (< 0.03 mm) containing graphite, plagioclase, grained rock consisting mainly of hornblende carbonate, and quartz. Aggregates (less than 30 and quartz with _some plagioclase and magnetite. mm) consisting of biotite, plagioclase, and The colour changes to dark grey and greyish quartz up to 0. 06 mm in size as well as 5 mm big green as the feldspar content increases. Carbo spots of phlogopite, sulphides, plagioclase, and nate veins and lenses occur as well as tremolite quartz of up to 0.2 mm size. Pyrrhotite and and some chalcopyrite towards the contact with pyrite occur as a fine impregnation, in thin layers the feis in the eastern limb. or in carbonate filling. The graphite which exists as impregnation and thin layers is enriched in Amphibolite. - Amphibolite occurs east as concordant zones in the C-ore. Transition to the well as west of the feis and carbonaceous schist in the eastern limb. It is a massive, locally Fig. l. Geological map of the Bidjovagge mining field, western slightly schistose, greenish black, fine grained Finnmark, Norway: 200N-750 S. NORSK GEOLOGISK TIDSSKRIFT 4 (1979) Bidjovagge mining field 329 330 N. B. Hollander NORSK GEOLOGISK TIDSSKRIFT 4 (1979)

600E 800E 1000E

Legend � Metadiabase m Amphibolite � Limestone E:TI Albite-fels B Black schist � Sedimentary greenstone � Schistose IWlJ Cu-mineralisation at or near surface � Cu-mineralisation in depth /20 Strike and dip j Fold axis with dip .,;-" Fault 25 50 75 100m _ % -Syn form - � - antiform NORSK GEOLOGISK TIDSSKRIFT 4 (1979) Bidjovagge mining fleld 331 feis is continuous, the difference lying mainly in The A-mineralization is limited to the north by the amount of carbonaceous material. The a N 80°E striking fault, dipping 85° SSE. The graphite, which probably was formed from or northern block was lifted as compared to the ganic material, is too fine grained to be economi southern one. Southwards the mineralization cally concentrated. gradually disappears from profile 60 N. It was on!y mined to proflle 50 N. Sedimentary greenstone. - A homogeneously Some poor mineralization was also found in layered or diffusely bedded rock with 2-20 mm the same rocks in the western limb where it thick layers, dark green to greyish green, fine extends southwards for some kilometres. grained with biotite, chlorite, amphibole, and white feid spar and traces of pyrite. Zones rich in The C-mineralization. - The best copper amphibole and layers of feis occur. The tran mineralization in the field- the C-ore - also Iies sition to feis is continuous. in the eastern limb of the big N-S-striking anticline (Fig. 2). It consists of a good eastern ore lying between 890 and 925 m east and a west Mineralizations ore between 850 and 880 m east (Figs. 3- 5). The The mineralizations are localized to the feis and northern end of the east ore Iies at profile l 040 S carbonaceous schist of the legs of an isocline. and the southern one at 1200 S in the open pit The amount of sulphides is varying and although (650-{)70 m a.s.l.) On leve! 600 (m a.s.l.) in the generally poor it increases rapidly in the faulted mine the ore Iies between 1050 and 1260 S. It is and brecciated areas. known down to 480 m a.s.l. extending from The best mineralizations in the field -call ed B, approximately 11 00-1160 S. The west ore is A, D, and C- are situated around the profiles 900 between 1085 and 1220 S on this level. In the N, 100 N, 450 S, and 1200 S respectively. The southern part it combines with the east ore. The present paper, however, does not consider the northern limit on leveis between 650 and 670 is B- and D-mineralizations. indicated to 1070 S while the southern end Iies around I180 S. The mineralizations extend both The A-mineralization.- The main mineralization north- and southwards in the eastern limb of the occurs in feis and schist on the eastern limb of fold, but are normally of very low grade. the big anticline (Fig. l), where the feis and the The mineralizations consist of chalcopyrite, interstratified carbonaceous schist form a pyrite, and some pyrrhotite; they occur as im slightly broken synform. pregnation, in irregular coarse grained albite The ore minerals are chalcopyrite, pyrrhotite, carbonate (ankerite and calcite) veins, and in and pyrite, all of which occur as impregnation irregular layers concordant to the diffuse layer and in carbonate veins mainly in the feis but also ing of the albite feis. The carbonate veins also in the adjacent parts of the schist. Accessory contain some muscovite, chlorite, and actinolite. minerals are magnetite, hematite, and complex The west-ore is rich in pyrite. Magnetite occurs Ti-V-minera1s (Mathiesen 1969). in the westernmost parts. Chalcopyrite is found The mineralization is fairly rich in gold; the in varying amounts dose to the carbonaceous analyses showed 2-7 ppm Au in ore giving schist together with some pyrrhotite. The west 20-102 ppm in 23% copper concentrate. The ore contains an impregnation of galena and lying wall between 140 and 80 N showed the sphalerite (max. 0.4% Pb and 1. 5% Zn per ton of highest gold content. ore). Although the age relationships between the Around 91 0 E the feis normally has only minerals have not yet been studied, the prelimi pyrite. The east ore, however, also contains nary observations showed that the sulphides of pyrrhotite with galena and sphalerite (max. 0.4% the veins are younger than the gangue minerals. Ph and 2.4% Zn per ton) together with Most of the pyrite seems to be older than the chalcopyrite. The central parts only contain chalcopyrite; pyrite is found in idiomorphic traces of sphalerite and even less amounts of crystals which are brecciated and replaced by galena. chalcopyrite. The central and synclinal feis is rich in chalcopyrite with pyrite, minor pyrrhotite, and

Fig. 2. Geological map of the Bidjovagge mining field, western magnetite. South and above the ore pyrrhotite Finnmark, Norway: 750-1600 S. with magnetite is common. 332 N. B. Hollander NORSK GEOLOGISK TIDSSKRIFT 4 (1979)

600

500

O 10 20 30 40 SOm

400 Leg end D Metadiabase m Amphibolite � Limes tone [2] Albite-fels - Black schist � Sedimentary greenstone � Schistose

PROFILE 1120 s

Fig. 3. Geological east-west profileof the Bidjovagge mining field: 1120 S.

The carbonaceous schist contains pyrrhotite schist are dipping steeply towards east around ' with some pyrite and chalcopyrite at the con 915-925 E and striking north to north 5o west. tacts with feis. The western part of the black schist (between The sulphides are mainly found in the feis and 880-900 E in profile 1120 S at 636-level) strikes adjacent parts of the schist. In lower parts of the north 5-10 o E. Dip is 60-S0° E. The black schist mine good mineralization occurs in the underly forms a synclinal with the closure to the north. ing schist in the copper-bearing synform around The fold axis dips 20-30° S, the central part being 900 E. Fig. 5 on the level 636 in the mine shows filled with partly mineralized feis. that the eastern feis and its contact with black Just south of the C-ore there is another NORSK GEOLOGISK TIDSSKRIFT 4 (1979) Bidjovagge mining field 333

600 +

>>> >>>> >>>> >>>> ·>>>> '>>>> .....>>> >>>> >>> '>>> >>

500 +

PROFILE 1200 S

Fig. 4. Geological east-west profile of the Bidjovagge mining field: 1200 S.

chalcopyrite mineralization. Lying on the west In addition there are 225,000 tons with 1.4% Cu side of the eastern carbonaceous schist this in the west ore. The reserves total approximately probably corresponds to the west ore in the C 2.3 million tons with 1.5% Cu. mine. It was found between approximately 1250- 1380 S from 600-500 m a.s.l. in the northern part Tectonics to 560-490 m a.s.l. in the southern part. This mineralization is probably connected with the The rocks in the Bidjovagge area are dominated one observed between 1440-1480 S roofing at by a generally north-south striking anticline (F 1) 500 and 480 m a. s. l. respectively and with a with a central part from 500 E in profile O to 650 vertical extension of approximately 100 m. E in profile 1400 S (Fig. l). The western limb Mineralogically and petrographically the se are of strikes north-south at 500 E, while the eastern the same type as the C-ore. one stands from 700 to l ,000 E. North of profile The ore reserves in the eastern C-ore are 700 S the fold axis dips to the north (15-30° at estimated as follows: profile 0). The carbonaceous schist just north west of D forms a syncline dipping north. The Between 600-650 m a.s.l. 550,000 t with 1.5% Cu dip varies from 10° N to 10° S between 700 and Between 54� m a.s.l. 150,000 t with 1.3% Cu 1000 S. South of 1000 S the dip gradually in Between 480-540 m a.s.l. 100,000 t with 1.3% Cu creases to 25-30° around profile 1200 S. These changes are due to flat-lying east-west striking The ore estimates in southern C-ore (as foldaxes (F2) which exist in the Caskias region. mentioned above) are: The folding has been very important for the

Between 540-640 m a.s.l. 515,000 t with 1.6% Cu localization of the sulphides. Both the feis and Between 480-540 m a.s.l. 785,000 t with 1.6% Cu carbonaceous schist are highly folded and often 334 N. B. Ho/lander NORSK GEOLOGISK TIDSSKRIFT 4 (1979)

11805 [•'•''.•.!.. �� Limes tone [2] Albite-fels - Black schist � Sedimentary

/10 Strike and dip t Fold axis with

-%-Synform

636 m 1220 NORSK GEOLOGISK TIDSSKRIFf 4 (1979) Bidjovagge mining fl.eld 335 disrupted. This caused the main mobilization of chemical analyses, and to Saga Petroleum a. s. for the exten the sulphides - both laterally towards troughs sive drafting. but especially the crests of the folds, and trans versely into cross-fractures. It appears that the relative mobility increases in the sequence py References rite-sphalerite-pyrrhotite-galena. The thickening Aalstad, l. 1961: Magnetic and electromagnetic airborne at the crests and troughs has been coupled with surveys. Kautokeino. Nor. Geo/. Unders. report nr. 258. Bølviken, B. 1959: Geochemical surveys in Bidjovaggel thinning out along limbs. This mobilization has Kautokeino. Kautokeino Kobber/elter Statens Un resulted in increased copper values in strongly dersøkelser (KKSU) report. folded beds as compared with their less de Bølviken, B. 1960: Kautokeino - case history. KKSU report. formed equivalents. BØlviken, B. 1961: Geochemical prospecting in Finnmark 1960. KKSU report. In addition it seems that faulting and fissuring Gjelsvik, T. 1955: A report on ore prospecting in Cashias. were of significant importance for improving the Nor. Geo/. Unders. report nr. 2606. ore grade, i.e. it was observed that as faulting Gjelsvik, T. 1958: Albiterich rocks in the Karelic Mountains in decreases the amount of ore minerals also de Finnmark, northern Norway. Nor. Geo/. Unders. 203, 60- 72. creases. The faulting has taken place after the Gjelsvik, T. 1958: Epigenetic copper mineralization in Finn N folding. The most prominent faults occur in mark. Nor. Geo/. Unders. 203, 49-59. 40-50° E. Another system strikes N 45-55° W. In Hollander, N. B. 1975: Report over the geological survey in addition there is a third one (very weakly shown) Bidjovagge mining area 1974/75. AlS Sydvaranger report. Hollander, N. B. 1975: AlS Sydvarangers regional ore in east-west. These represent a combination of prospecting in the Kautokeino-Bidjovagge area (KABI), blockfaulting and fissuring. As noted above, the Finnmark, 1974. AlS Sydvaranger report. A-mineralization is limited to the north by east Holmsen, P., Padget, P. & Pehkonen, E. 1957: The Pre west faulting. The C and D mineralizations Iie in cambrian geology of Vest-Finnmark, Northern Norway. Nor. Geo/. Unders. 201, 107 p. areas with movements in north-easterly direc Ingvaldsen, K. 1958: Report of the field season 1958. KKSU tion. In many other parts the rocks are broken report. with secondary chloritization along fractures but Ingvaldsen, K. 1960: Report of the investigations of Bid with no signs of displacement. jovagge 1956-1959. KKSU report. Ingvaldsen, K. 1963: Report of the investigations of Bid jovagge 1956-1962. KKSU report, Nr. 3375. Ingvaldsen, K., Paulsen, G. & Mathiesen, C. O. 1969: Report The ore genesis over investigations 1956-1965. KKSU report, nr. 3837. The original geological setting of the rocks in Kruse, A. 1967: A preliminary report on Bidjovagge C. AlS Bleikvassli report. Caskias was a sedimentary basin in which there Kvalheim, A. 1959: Report of the year 1959 for Statens was a widespread volcanic activity. The feis Råstoff-Laboratorium. KKSU report. probably represents the volcanic ashes settling Kvalheim, A. & Næss 1967: Geochemical surveys in Bid in a reducing millieu of organic black clays jovagge-Lamsejaure, Kautokeino. Nor. Geo/. Unders. re port nr. 724 A. alternating with more carbonaceous material. Logn, Ø & Sakshaug, F. 1958: A geophysical survey of The sulphides could have come from submarine BidjovaggeiKautokeino. Nor. Geo/. Unders. report nr. 185. syngenetic exhalations being precipitated in the Mathiesen, C. O. 1957: A geological report on Bidjovagge. smaller depths in various amounts. Later folding KKSU report. Mathiesen, C. O. 1959: A summary geological report on and faulting mobilized the sulphides and pro Bidjovagge 1958. KKSU report. vided new space for deposition and concentra Mathiesen, C. O. 1967: Report over investigations 1966. tion across the original sedimentary boundaries. KKSU report nr. 3838. Mathiesen, C. O. 1969: An occurrence of unusual minerals at Acknowledgements. The author is indebted to AlS Bidjovagge, Northern Norway. Nor. Geo/. Unders. 266, Sydvaranger for permission to publish the data, and to the 86-104. director of the prospectingdepartment, T. L. Sverdrup, for his Mathiesen, C. O. 1970: A geological-geophysical map over the great interest and many fruitfuldiscussions. Thanks are due to Bidjovagge area. 1:10,000. Map published by Nor. Geo/. Professor J. A. W. Bugge for valuable discussions and con· Unders. structive criticism of this pa per. Sakshaug, F. 1957: A geophysical survey of Bidjovaggel In the field the author bad great hel p fr om geologists H. Kautokeino. Nor. Geo/. Unders. report nr. 185. Delin and S. E. Bull. He is most grateful to the technical staff Sakshaug, F. 1959: A geophysical survey of Bidjovaggel at the laboratory of the mining office in Kirkenes for all Kautokeino. Nor. Geo/. Unders. report nr. 208. Sakshaug, F. 1961: A magnetic survey of Bidjovagge. Nor. Geo/. Unders. report nr. 276/E. Sakshaug, F. 1961: A geophysical survey of Bidjovagge, Fig. 5. Geological map of the C-mine of the Bidjovagge mining LæmsejauretiKautokeino. Nor. Geo/. Unders. report nr. field: 636 m above sea levet. 306. 336 N. B. Ho/lander NORSK GEOLOGISK TIDSSKRIFT 4 (1979)

Sakshaug, F. 1963: An e1ectromagnetic survey of Bidjovagge/ Kautokeino. Nor. Geo/. Unders. report nr. 525. Sakshaug, F. 1965: An e1ectromagnetic survey of Bidjovagge, Kautokeino. Nor. Geo/. Unders. report nr. 604. Sverdrup, T. L. 1963: Investigations of the occurrence of Au in Bidjovagge, Finnmark. KKSU report nr. 4440. Tau, H. 1959--1967: Regional ore prospecting on the Green stones Belt of Cashias. Nor. Geo/. Unders. report nrs. 548 A, 620 A, 756 & 959. Tau, H. 1964: Microboulders in Cashias. Nor. Geo/. Unders. report nrs. 548 C & 620 B.