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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 Vol. 59, pp. 327-336. Oslo 1979. ISSN 0029-196X. Geologisk Tidsskrift, 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. Bidjovagge copper mines are situated on the Caskias mountain 69"17' N, 22°29' E, 700 ma. s. l. (Fig. l) in Finnmark, north Norway. The mineralizations occur in what is known as the Caskias-Stuorajaure Group, which in cludes greenschists, homblendeschists, graphitic schists, greenstones, and plagioclase-carbonate rocks. Amphibolites and diabases, which pre sumably represent rocks of intrusive character, are common (Holmsen et. al. 1957, Mathiesen 195 7, 1959, 1967). What is known of the discovery of the mineralization dates back to the late 1940's or early 1950's when two Lapps found sulphides on the Caskias mountain. Some rumours, however, indicate that it was known as early as in the 1920's. Whatever the truth, the claims were staked in 1952. Boliden Mining Company, Swe den, started their field work the same year. The application for a concession was, however, re jected. In 1955 the Norwegian government made an agreement with the owners of the claims, bought the geological and geophysical reports from Boliden, and started investigations. In 1954-195 6 Norges geologiske undersØkelse (NGU) made a regional geological mapping. From 195 6 geologi ca! mapping, geophysical measurements, geo chemical sampling, and diamond drilling were carried out by Kautokeino Kobberfelter Statens UndersØkelser (KKSU), which was specially 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 & co. , P. O. Box 550, N-1301 Sandvika, Norway. 1963 KKSU was taken over by NGU, which continued the investigations in the next three years resulting in the following estimates of the tonnage of the mineralizations (i. e. Ingvaldsen, Paulsen & Mathiessen 1966): A: B: C: D: Total: Proven reserves (ton) % Cu Probable reserves (ton) 302,000 253,000 2,065,000 360,000 2, 980,000 2. 10 1. 8 3 1. 8 4 1. 8 4 1. 80 100,000 5 0,000 250,000 200,000 600,000 In addition 1/2 ppm Au was indicated. In 1967 A/S Bidjovagge Mining Company was formed by AlS Bleikvassli Mining Company. The plant was completed in 1970. Production started the same year. In 1974 A/S Sydvaranger bought A/S Bleikvassli Mining Company and thereby also Bidjovagge. A systematic eva1ua tion of the mine and prospecting in the surround ings started in 1974. During 1974-1975 the author was in charge of the geological work in the mining field as well as the regional prospecting in western Finnmark. Due to the falling prices of copper and small production the mine was closed down in mid1975. 328 N. B. NORSK GEOLOGISK TIDSSKRIFT 4 (1979) Ho/lander Geology General From west to east the rocks around the C-mine are carbonate-rich rocks, feis, amphibolite, carbonaceous schist, diabase, alternating feis, and carbonaceous schist locally very rich in chalcopyrite and pyrite, and finally greenstone with amphibolite and diabase (Figs. l and 2). These rocks form part of the Caskias-Group which represents a period of intense and wide spread rather basic volcanic activity in the Karelic geosyncline. The present survey has, however, been carried out in much greater detail than the earlier ones. Generally, Mathiessen's map (1970) compares well with the present one. Rocks Carbonate rich rocks. - These have only been found in two outcrops but are recognized in many cores west and southwest of the C-mine. They are diffusely layered, light brown-grey, slightly weathered, fine to medium grained rocks consisting of dolomitic and ankeritic carbonate minerals with some amphibole. Pyrite occurs as an accessory mineral in the eastern limestone (lying around 800 E south of profile 1100 S) which is fairly dean. The western carbonate rock (situated between 600 and 775 E) is rich in hornblende and to some extent also biotite. Locally it contains actinolite and is slightly schistose. Diabase (metadiabase).- The diabase stretches from profile O in the north to the south and southeast, forming the upper central part as well as part of the eastern limb of the big anticline. The upper central part of the fold is filled with the above mentioned carbonate-rich rock and the diabase. It is massive greenish black, fine to medium grained rock consisting mainly of hornblende and quartz with _some plagioclase and magnetite. The colour changes to dark grey and greyish green as the feldspar content increases. Carbo nate veins and lenses occur as well as tremolite and some chalcopyrite towards the contact with the feis in the eastern limb. Amphibolite. - Amphibolite occurs east as well as west of the feis and carbonaceous schist in the eastern limb. It is a massive, locally slightly schistose, greenish black, fine grained rock consisting of hornblende, biotite, quartz, albite-rich plagioclase, carbonate, magnetite and pyrrhotite, and some chlorite. Aggregates (1.5-. 10 mm) of hornblende are common. Feis. - This name is introduced to describe a felsic, fine grained, massive, metamorphic rock consisting of albite, quartz, and calcite. It has a diffuse layering and/or heterogeneous bedding with < 5 mm thick bands, white to greyish white, grey or redbrown with a grain size of 0. 14l. 3 mm. The main mineral is albite, quartz and calcite occurring in smaller amounts. Horn blende and biotite exist in small quantities. Muscovite has been found but is rare. Some 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 crystals were found in drillhole 1440 S, 915 E, at 477 m, a.s.l. The feis is locally very rich in chalcopyrite, pyrite, and pyrrhotite. Magnetite is usually an accessory mineral. Galena and sphal erite have been found. The feis is sometimes so fine grained ( <0. 01 mm) that identification of the minerals in thin sections becomes impossible. The rock is cut by irregular veins (< 5 cm) filled with calcite and dolomiie, some quartz and albite, with accessory biotite and iddingsite. They can locally be very rich in chalcopyrite. The feis is very similar to the leptites found in the Precambrian of northern and middle Swe den. Carbonaceous schist. - Diffusely bedded to homogeneously layered, only locally schistose or even brecciated, black to greyish black with thin light grey to greyish white hands. The dark hands are less than 10 mm thick and the light ones less than 2 mm. The difference in colours depends on the relative amounts of light and dark minerals. The rock is very fine grained (< 0. 03 mm) containing graphite, plagioclase, carbonate, and quartz. Aggregates (less than 30 mm) consisting of biotite, plagioclase, and quartz up to 0. 06 mm in size as well as 5 mm big spots of phlogopite, sulphides, plagioclase, and quartz of up to 0. 2 mm size. Pyrrhotite and pyrite occur as a fine impregnation, in thin layers or in carbonate filling. The graphite which exists as impregnation and thin layers is enriched in concordant zones in the C-ore. Transition to the l. Geological map of the Bidjovagge mining field, western Finnmark, Norway: 200N-750 S. Fig. NORSK GEOLOGISK TIDSSKRIFT 4 (1979) Bidjovagge mining field 329 330 N. B. Hollander NORSK GEOLOGISK TIDSSKRIFT 4 (1979) 600E 800E Legend � m � E:TI B � � IWlJ � /20 j Metadiabase Amphibolite Limestone Albite-fels Black schist Sedimentary greenstone Schistose Cu-mineralisation at or near surface Cu-mineralisation in depth Strike and dip Fold axis with dip .,;-" Fault _ % -Syn form -�- antiform 25 50 75 100m 1000E Bidjovagge mining fleld NORSK GEOLOGISK TIDSSKRIFT 4 (1979) feis is continuous, the difference lying mainly in the amount of carbonaceous material. The 331 The A-mineralization is limited to the north by 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 feidspar and traces of pyrite. Zones rich in The 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 Mineralizations ore lying between 890 and 925 m east and a west The mineralizations are localized to the feis and northern end of the east ore Iies at profile l040 S C-mineralization. anticline (Fig. 2). - The best copper It consists of a good eastern ore between 850 and 880 m east (Figs. 3- 5). The 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 - c alled B, approximately 1100-1160 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, 1 00 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 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. around I180 S. The mineralizations extend both the big anticline (Fig. l), where the feis and the interstratified carbonaceous schist form a slightly broken synform. The mineralizations consist of chalcopyrite, pyrite, and some pyrrhotite; they occur as im 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 in the westernmost parts. Chalcopyrite is found Ti-V-minera1s (Mathiesen 1969). 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 910 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 Most of the pyrite seems to be older than the chalcopyrite. The central parts only contain and 2.4% Zn per ton) together with 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 Finnmark, Norway: 750-1600 S. magnetite. South and above the ore pyrrhotite with magnetite is common. 332 N. B. Hollander NORSK GEOLOGISK TIDSSKRIFT 4 (1979) 600 500 O 10 20 30 40 SOm Leg end 400 PROFILE D m � [2] � Metadiabase � Schistose Amphibolite Limes tone Albite-fels Black schist Sedimentary greenstone 1120 s Fig. 3. Geological east-west profile of 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 tacts with feis. The western part of the black schist (between The sulphides are mainly found in the feis and adjacent parts of the schist. In lower parts of the and striking north to north 5o west. 880-900 E in profile 1120 S at 636-level) strikes 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 Bidjovagge mining field NORSK GEOLOGISK TIDSSKRIFT 4 (1979) 333 + 600 >>> >>>> >>>> >>>> ·>>>> '>>>> ..... >>> >>>> >>> '>>> >> + 500 PROFILE 1200 S Fig. 4. Geological east-west profile of the Bidjovagge mining field: 1200 S. 225,000 In addition there are in the west ore. The reserves total approximately probably corresponds to the west ore in the C 2.3 million tons with 1.5% tons with 1. 4% chalcopyrite mineralization. Lying on the west side of the eastern carbonaceous schist this Cu Cu. mine. It was found between approximately 1250- 1380 S from 600-500 to 560-490 m a.s. l. m a. s. l. in the northern part in the southern part. This mineralization is probably connected with the one observed between 500 and vertical 480 1440-1480 S roofing at m a. s. l. respectively and with a extension of approximately 100 m. Mineralogically and petrographically the se are of the same type as the C-ore. The ore reserves in the eastern C-ore are estimated as follows: Between 600-650 m a.s.l. Between 54� m a.s.l. Between 480-540 m a.s.l. The ore estimates Between 480-540 m a.s.l. The rocks in the Bidjovagge area are dominated by a generally north-south striking anticline (F 1 ) 500 E in profile O to 650 l). The western limb strikes north-south at 500 E, while the eastern one stands from 700 to l ,000 E. North of profile 700 S the fold axis dips to the north (15-30° at profile 0). The carbonaceous schist just north with a central part from E in profile 1400 S (Fig. west of D forms a syncline dipping north. The Cu 150,000 t with 1.3% Cu 100,000 t with 1.3% Cu in southern C-ore 10° N to 10° S between 700 and 1000 S the dip gradually in 25-30° around profile 1200 S. These dip varies from 550,000 t with 1.5% mentioned above) are: Between 540-640 m a.s.l. Tectonics 1000 S. South of creases to (as changes are due to flat-lying east-west striking foldaxes (F2) which exist in the Caskias region. The folding has been very important for the Cu 785,000 t with 1.6% Cu 515,000 t with 1.6% localization of the sulphides. Both the feis and carbonaceous schist are highly folded and often 334 N. B. 11805 Ho/lander [•'•'' .•.!.. ���� [2] � !?Æ.] /10 t Limes tone Albite-fels Black schist Sedimentary <Teenstone Strike and dip Fold axis with -%-Synform 1220 636 m NORSK GEOLOGISK TIDSSKRIFT 4 (1979) Bidjovagge mining fl.eld NORSK GEOLOGISK TIDSSKRIFf 4 (1979) disrupted. This caused the main mobilization of the sulphides - both laterally towards troughs but especially the crests of the folds, and trans versely into cross-fractures. It appears that the relative mobility increases in the sequence py rite-sphalerite-pyrrhotite-galena. The thickening at the crests and troughs has been coupled with thinning out along limbs. This mobilization has resulted in increased copper values in strongly folded beds as compared with their less de formed equivalents. In addition it seems that faulting and fissuring were of significant importance for improving the ore grade, i.e. it was observed that as faulting decreases the amount of ore minerals also de creases. The faulting has taken place after the folding. The most prominent faults occur in N 40-50° E. Another system strikes N 45-55° W. In addition there is a third one (very weakly shown) in east-west. These represent a combination of blockfaulting and fissuring. As noted above, the A-mineralization is limited to the north by east west faulting. The C and D mineralizations Iie in areas with movements in north-easterly direc tion. In many other parts the rocks are broken with secondary chloritization along fractures but with no signs of displacement. The ore genesis The original geological setting of the rocks in Caskias was a sedimentary basin in which there was a widespread volcanic activity. The feis probably represents the volcanic ashes settling in a reducing millieu of organic black clays alternating with more carbonaceous material. The sulphides could have come from submarine syngenetic exhalations being precipitated in the smaller depths in various amounts. Later folding and faulting mobilized the sulphides and pro vided new space for deposition and concentra tion across the original sedimentary boundaries. The author is indebted to AlS Sydvaranger for permission to publish the data, and to the director of the prospecting department, T. L. Sverdrup, for his great interest and many fruitful discussions. Thanks are due to Professor J. A. W. Bugge for valuable discussions and con· structive criticism of this paper. In the field the author bad great help from geologists H. Delin and S. E. Bull. He is most grateful to the technical staff at the laboratory of the mining office in Kirkenes for all Acknowledgements. 335 chemical analyses, and to Saga Petroleum a. s. for the exten sive drafting. References Aalstad, l. 1961: Magnetic and electromagnetic airborne surveys. Kautokeino. Nor. Geo/. Unders. report nr. 258. Bølviken, B. 1959: Geochemical surveys in Bidjovaggel Kautokeino. Kautokeino Kobber/elter Statens Un dersøkelser (KKSU) report. Bølviken, B. 1960: Kautokeino - case history. KKSU report. BØlviken, B. 1961: Geochemical prospecting in Finnmark 1960. KKSU report. Gjelsvik, T. 1955: A report on ore prospecting in Cashias. Nor. Geo/. Unders. report nr. 2606. Gjelsvik, T. 1958: Albiterich rocks in the Karelic Mountains in Finnmark, northern Norway. Nor. Geo/. Unders. 203, 6072. Gjelsvik, T. 1958: Epigenetic copper mineralization in Finn mark. Nor. Geo/. Unders. 203 49-59. Hollander, N. B. 1975: Report over the geological survey in Bidjovagge mining area 1974/75. AlS Sydvaranger report. Hollander, N. B. 1975: AlS Sydvarangers regional ore prospecting in the Kautokeino-Bidjovagge area (KABI), Finnmark, 1974. AlS Sydvaranger report. Holmsen, P., Padget, P. & Pehkonen, E. 1957: The Pre cambrian geology of Vest-Finnmark, Northern Norway. Nor. Geo/. Unders. 201, 107 p. Ingvaldsen, K. 1958: Report of the field season 1958. KKSU , report. Ingvaldsen, K. 1960: Report of the investigations of Bid 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 over investigations 1956-1965. KKSU report, nr. 3837. Kruse, A. 1967: A preliminary report on Bidjovagge C. AlS Bleikvassli report. Kvalheim, A. 1959: Report of the year 1959 for Statens Råstoff-Laboratorium. KKSU report. Kvalheim, A. & Næss 1967: Geochemical surveys in Bid jovagge-Lamsejaure, Kautokeino. Nor. Geo/. Unders. re port nr. 724 A. Logn, Ø & Sakshaug, F. 1958: A geophysical survey of BidjovaggeiKautokeino. Nor. Geo/. Unders. report nr. 185. Mathiesen, C. O. 1957: A geological report on Bidjovagge. KKSU report. Mathiesen, C. O. 1959: A summary geological report on Bidjovagge 1958. KKSU report. Mathiesen, C. O. 1967: Report over investigations 1966. KKSU report nr. 3838. Mathiesen, C. O. 1969: An occurrence of unusual minerals at Bidjovagge, Northern Norway. Nor. Geo/. Unders. 266, 86-104. Mathiesen, C. O. 1970: A geological-geophysical map over the Bidjovagge area. 1:10,000. Map published by Nor. Geo/. Unders. Sakshaug, F. 1957: A geophysical survey of Bidjovaggel Kautokeino. Nor. Geo/. Unders. report nr. 185. Sakshaug, F. 1959: A geophysical survey of Bidjovaggel Kautokeino. Nor. Geo/. Unders. report nr. 208. Sakshaug, F. 1961: A magnetic survey of Bidjovagge. Nor. Geo/. Unders. report nr. 276/E. Geological map of the C-mine of the Bidjovagge mining field: 636 m above sea levet. Fig. 5. Sakshaug, F. 1961: A geophysical survey of Bidjovagge, LæmsejauretiKautokeino. Nor. Geo/. Unders. report nr. 306. 336 N. B. Ho/lander 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. NORSK GEOLOGISK TIDSSKRIFT 4 (1979)