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Geochemical gold prospecting at Vinsanmaa, northern Finland
Journal of Geochemical Exploration, 39 ( 1991 ) 379-386
379
Elsevier Science Publishers B.V., Amsterdam
Geochemical gold prospecting at Vinsanmaa, northern Finland Matti Xyr~is Geological Survey of Finland, Department of Geochemistry, 96100 Rovaniemi, Finland (Received January 24, 1990)
ABSTRACT ~,ydis, M., 1991. Geochemical gold prospecting at Vinsanmaa, northern Finland. In: A.J. BjiSrklund (Editor), Gold Geochemistry in Finland. J. Geochem. Explor., 39: 379-386. At Vinsanmaa, Rovaniemi rural commune, northern Finland, there is a mineralized quartzite vein in albite diabase, which has been investigated by Outokumpu Co. The vein averages 3 g/t Au. In the regional till-geochemical mapping done by the Geochemical Department of the Geological Survey of Finland a clear and widespread Au anomaly was found in till about 1 km SE of the vein. The investigations were made step by step. In the first two stages the samples were taken with light percussion drill, in the third stage with hydraulic hammer and finally with diamond drilling. Geophysical measurements were also carried out. The fine fraction of till and weathered bedrock and also the diamond drill core samples were analyzed for Co, Cu, Mn, Ni, Pb, Zn and Ag by flame atomic absorption and Au and Pd by flameless atomic absorption. The results show that the widespread anomaly cannot have been caused by the previously known vein. The Au occurs in rocks in a very fine-grained form and has clearly been enriched into the fine fraction of weathered bedrock. Only in one diamond drill hole anomalous Au contents were found. The highest Au content is in the upper part of altered diabase. The results indicate clearly that in the Vinsanmaa area there are no other Au showings like the vein already known. The widespread Au anomaly in till resembles the contents in bedrock and has been caused principally by weathering of diabase rock.
INTRODUCTION
The study area, Vinsanmaa, is located in Rovaniemi rural commune, some 25 km south of the city of Rovanimi, northern Finland. Outokumpu Co made exploration in Vinsanmaa in the 1960s. A mineralized quartzite vein containing chalcopyrite (Cu about 4%) was found in albite diabase about one km NW of the present study area. The vein averages 3 g/t Au (Rouhunkoski and Isokangas, 1974). The occurrence was, however, too small for mining. In the regional till-geochemical mapping done by the Geochemical Department of the Geological Survey of Finland (GSF) at the beginning of the 1980's the Vinsanmaa vein appeared as a multielement anomaly in till (Manner and 0375-6742/91/$03.50
© 1991 - - Elsevier Science Publishers B.V.
380
M. AYRXS THE DIRECTION OF ICE F L O W
YOUNGER
"
I0"
'o
~>
.,
....
Au ppb <
500
m • • •
J
A AND B
4
47 815 16 - 31 >31
COPPER-GOLD-QUARTZ VEIN THE SOUTHERN CONTACT OF ALBITE DIABASE INTRUSIVE THE LINES OF SAMPLING BY HYDRAULIC HAMMER
Fig. 1. Gold anomalies in till in the Vinsanmaa area. After Koivisto ( 1984 ).
Koivisto, 1981 ). In the next step the till investigations were carried out over an area of 1 × 2 km. In this stage, a widespread Au anomaly in till was found 1 km SE of the known Vinsanmaa vein (Fig. 1 ). The vein cannot be the source of this anomaly because the known direction of ice flow is from the west. The Au content was high and it was assumed, that the anomaly was caused by local Au contents in bedrock. Therefore, detailed investigation was carried out. GEOLOGY
Most of the study area is albite diabase, which belongs to the Middle Jatulian Formation in the Per~ipohja schist area. The albite diabases occur as dykes conforming mostly to the layering of the surrounding bedrock. The main minerals are albite, amphibole, epidote and fine-grained quartz (Perttunen, 1983a). The albite is saussuritized and occasionally there is plenty of carbonate alteration. The texture is subophitic or ophitic and the diabase dykes are usually differentiated. The host rock is generally quartzite, in which the albite diabase occurs as intercalations. In the southern part of the area (Fig. 2). there is the Pisavaara quartzite, a clearly layered, grey or reddish orthoquartz-
GEOCHEMICAL GOLD PROSPECTING AT VINSANMAA, NORTHERN FINLAND
381
lOm , i N tll
4
~
3
5
6
.
S
t;t
i
i
0
100
I
200
I
I
300
400
I
500 m
Fig. 2. The bedrock at Vinsanmaa after Perttunen ( 1983a, b) and the diamond drilling results. A and B are the lines of the sampling with hydraulic hammer.
ite. The main mineral is quartz which occurs as roundish grains. The matrix material is fine-grained quartz, occasionally dolomite, and a little sericite (Perttunen, 1983b). The western part of the area is poorly known, because of the lack of outcrops. In the far west there are greenstones. The geomorphological landscape type is ground moraine. The bedrock is overlain by lodgement till, 5 to 12 m in thickness. The surface of the bedrock is usually preglacially weathered to a depth of 1 to 2 m. In the topographically lower parts the till is covered by peat deposits. Only one till bed occurs, and the direction of ice transport is from the west. SAMPLING
In regional mapping the till samples were taken with light percussion drill at l-m depth intervals to the attainable depth, at a density of one sampling
382
M. ,~YR,~,S 3 4
7362.800 Jc
4@ 5®
2@
10~
/
7
6"
A '@
B
/ x
@ Drilling s i t e
i
i
q
t
i
O
100
200
300
400
i
500 m
Fig. 3. Gold contents (ppb) in the - 0 . 0 6 m m fraction of weathered bedrock in the Vinsanmaa area.
point/42. In the second stage (Fig. 1 ), the samples were taken with percussion drill at 50-m intervals along lines 200 m apart. One sample was taken from the bottom part of the till layer, and another 1 to 2 m above the bottom sample. Also, if possible, samples from weathered bedrock were taken. In the third stage (Figs. 2, 3 and 4), sampling was done with hydraulic h a m m e r from till and weathered bedrock. Two lines were sampled across the anomaly found in the second stage. The sampling point distance varied from 50 to 10 m, with the 10-m interval being in the middle of the lines. In the final stage, vertical d i a m o n d drilling was carried out to depths of 5 to l 0 m in unweathered bedrock at 11 sites (Figs. 2, 3 and 4). ANALYSIS
The fine fraction ( - 0 . 0 6 m m ) of till and weathered bedrock, as well as the pulverized coarse fraction ( + 2.0 m m ) of weathered bedrock and the drill
GEOCHEMICAL GOLD PROSPECTING AT VINSANMAA, NORTHERN FINLAND
383
7362,B00~-
4@
21~ 6-
2-
5@ 10@
8@ ,;~2.
6@
g@
11@
'~ 3
J
B
@ Drilling site
t O
I 100
i 200
i 300
i 400
i 500 m
Fig. 4. Gold contents (ppb) in the - 0 . 0 6 m m fraction of till in the Vinsanmaa area.
core samples were analyzed in the GSF laboratory in Rovaniemi. The drill cores were usually analyzed at 1-m sections. The samples were analyzed for Co, Cu, Mn, Ni, Pb, Zn and Ag by flame atomic absorption (air-acetylene), Au and Pd by flameless atomic absorption after aqua regia leach. The methods of Au and Pd analyses are described by Kontas ( 1981 ) and Kontas et al. (1986). RESULTS AND DISCUSSION
The results of the second stage of till sampling are shown in Figure 1. There are two significant Au anomalies. The northernmost anomaly, some 100 m long, is caused by the known mineralized quartz vein. The highest Au contents in till in this anomaly are about 30 ppb. The most significant and widespread Au anomaly, 0.5 × 1 km in size, is in the central southeastern part of
384
M. ,~YRAS
the study area. The bedrock in study area is covered by only one till bed, transported from the west by the younger glaciation. The known quarz vein is probably not the source of the large anomaly. The highest Au content in till of this anomaly is 270 ppb. Beneath the till bed some samples of weathered bedrock were found, in which the Au contents vary from 23 to 85 ppb. It seems obvious that the Au anomaly in till has been caused by Au contents in local bedrock (Koivisto, 1984). The results of the third stage show that Au is enriched into the fine fraction of weathered bedrock (Table 1 ), whereas Au contents in the coarse fraction are low. Copper and cobalt are also enriched into the fine fraction of the weathered rock material, but this is not so clear as in the case of Au. The contents of Au, Cu and Co are much the same in the fine fractions of till and weathered bedrock as seen as median values in Table 1. On both lines (Figs. 3 and 4) the two highest Au contents (240 and 250 ppb ) are in weathered rock, which has been interpreted as albite diabase. The highest Au content in till is on the line B at the same point as the high content in weathered bedrock. The highest Cu contents are also in the fine fraction of weathered albite diabase. The Cu anomalies are, however, larger than the Au anomalies. The highest Co contents normally coincide with high Cu contents. The results indicate that the Au anomaly has its origin in the local bedrock. However, this study does not show the mode of occurrence of Au in the bedrock of the area. In 1986, the Geophysical Department of the GSF made magnetic and VLF-R measurements in the study area and on one line acrossing the known quartz vein. The anomaly patterns are in both cases much the same, the levels being very close to one another. Therefore, it was assumed that other Au mineralization like the known quartz vein could exist in the study area. In the final stage of the investigations, the diamond drilling, anomalous Au contents were found only in drill hole No. 6 (max. 420 ppb), which penetrates the albite diabase with a large number of narrow (about 10 cm) quartz veins (Fig. 5 ). In the upper part of the diabase there is saussuritization, carTABLE 1 The average contents (Y) and medians (Md) of Au, Co and Cu in till (the - 0 . 0 6 m m ) and in the fine ( - 0 . 0 6 m m ) and the pulverized coarse ( + 2 m m ) fraction of weathered bedrock in the Vinsanmaa area. Au(ppb)
Till Weathered bedrock (fine) Weathered bedrock (coarse)
2.6 16.0 0.9
Co(ppm)
Cu(ppm)
Md
~
Md
Y
Md
2.5 3.2 1.0
21.9 26.5 25.3
18.5 17.7 10
76.2 134.2 98.4
48 60 20
GEOCHEMICALGOLDPROSPECTINGATVINSANMAA,NORTHERNFINLAND
Q U A R T Z VEIN
Au ppb
Cuppm
420
3370
20
503
20
334
20
203
40
569
<10
9
385
ALBITE DIABASE OPHITIC SAUSSURITIZATION PLENTY OF PYRITE
Q U A R T Z VEIN ALBITE DIABASE C A R B O N A T E ALTERATION PYRITE
QUARTZ VEIN ALBITE DIABASE ALTERED PYRITE
Q U A R T Z VEIN ALBITE DIABASE LOW PYRITE CONTENT
I
QUARTZ VEIN ALBITE DIABASE SAUSSURITIZATION
I <10
2
Fig. 5. The rock types and Au and Cu contents in drill hole number 6 in the Vinsanmaa area.
bonate alteration and a great deal o f pyrites. The highest Au content is in the upper part o f the diabase. Also at a depth o f 16 to 17 m there is a slight increase in Au contents. The highest Cu contents coincides the highest Au contents. Also in hole No. 3 there is a slight increase in Au contents. The results o f diamond drilling shows that in the Vinsanmaa study area there are no other Au occurrences like the previously known mineralized vein. There is a clear increase o f Au contents in contact zones o f the diabase, and the Au is associated with pyrites. The widespread Au anomaly in till resembles the contents in weathered bedrock and has been caused principally by weathering o f diabase bedrock.
REFERENCES Koivisto, T., 1984. Geokemialliset tarkistustutkimukset Per~ipohjan liuskealueella: Moreenigeokemialliset kultatutkimukset Kivimaan ja Vinsan tunnettujen Cu-Au-juonimuodostumien ymp~iristSss~i. Rep., Arch. Geol. Surv. Finl., Rovaniemi, 19 pp. (in Finnish) (unpubl.).
386
M. AYRAS
Kontas, E., 1981. Rapid determination of gold by flameless atomic absorption spectrometry in the ppb and ppm ranges without organic solvent extraction. Atomic Spectros., 2: 59-61. Kontas, E., Niskavaara, H. and Virtasalo, J., 1986. Flameless Atomic Absorption Determination of Gold and Palladium in Geological Reference Samples. Geostandard Newslett., 10: 169-171. Manner, R. and Koivisto, T., 1981. Estitutkimusraportti karttalehden 2633 (Koivu) alueelta. Rep. The archieves of the Geological Survey of Finland, Rovaniemi, 22 pp. (in Finnish) (unpubl.). Perttunen, V., 1983a. Per~ipohjan liuskealueen vulkaniiteista. Vulkaniittisymposio, Pohtimolampi 3.-4.3.1983. Unpublished report in Finnish. Arch. Geol. Surv. Finl., Rovaniemi, 6 pp. ( in Finnish ) (unpubl.). Perttunen, V., 1983 b. Per~ipohjan etel~iosan geologia. Thesis, The University of Helsinki. 36 pp. (in Finnish) (unpubl.). Rouhunkoski, P. and Isokangas, P., 1974. The copper-gold vein deposit of Kivimaa at Tervola, N-Finland. Bull. Geol. Soc. Finl., 46: 29-35.
379
Elsevier Science Publishers B.V., Amsterdam
Geochemical gold prospecting at Vinsanmaa, northern Finland Matti Xyr~is Geological Survey of Finland, Department of Geochemistry, 96100 Rovaniemi, Finland (Received January 24, 1990)
ABSTRACT ~,ydis, M., 1991. Geochemical gold prospecting at Vinsanmaa, northern Finland. In: A.J. BjiSrklund (Editor), Gold Geochemistry in Finland. J. Geochem. Explor., 39: 379-386. At Vinsanmaa, Rovaniemi rural commune, northern Finland, there is a mineralized quartzite vein in albite diabase, which has been investigated by Outokumpu Co. The vein averages 3 g/t Au. In the regional till-geochemical mapping done by the Geochemical Department of the Geological Survey of Finland a clear and widespread Au anomaly was found in till about 1 km SE of the vein. The investigations were made step by step. In the first two stages the samples were taken with light percussion drill, in the third stage with hydraulic hammer and finally with diamond drilling. Geophysical measurements were also carried out. The fine fraction of till and weathered bedrock and also the diamond drill core samples were analyzed for Co, Cu, Mn, Ni, Pb, Zn and Ag by flame atomic absorption and Au and Pd by flameless atomic absorption. The results show that the widespread anomaly cannot have been caused by the previously known vein. The Au occurs in rocks in a very fine-grained form and has clearly been enriched into the fine fraction of weathered bedrock. Only in one diamond drill hole anomalous Au contents were found. The highest Au content is in the upper part of altered diabase. The results indicate clearly that in the Vinsanmaa area there are no other Au showings like the vein already known. The widespread Au anomaly in till resembles the contents in bedrock and has been caused principally by weathering of diabase rock.
INTRODUCTION
The study area, Vinsanmaa, is located in Rovaniemi rural commune, some 25 km south of the city of Rovanimi, northern Finland. Outokumpu Co made exploration in Vinsanmaa in the 1960s. A mineralized quartzite vein containing chalcopyrite (Cu about 4%) was found in albite diabase about one km NW of the present study area. The vein averages 3 g/t Au (Rouhunkoski and Isokangas, 1974). The occurrence was, however, too small for mining. In the regional till-geochemical mapping done by the Geochemical Department of the Geological Survey of Finland (GSF) at the beginning of the 1980's the Vinsanmaa vein appeared as a multielement anomaly in till (Manner and 0375-6742/91/$03.50
© 1991 - - Elsevier Science Publishers B.V.
380
M. AYRXS THE DIRECTION OF ICE F L O W
YOUNGER
"
I0"
'o
~>
.,
....
Au ppb <
500
m • • •
J
A AND B
4
47 815 16 - 31 >31
COPPER-GOLD-QUARTZ VEIN THE SOUTHERN CONTACT OF ALBITE DIABASE INTRUSIVE THE LINES OF SAMPLING BY HYDRAULIC HAMMER
Fig. 1. Gold anomalies in till in the Vinsanmaa area. After Koivisto ( 1984 ).
Koivisto, 1981 ). In the next step the till investigations were carried out over an area of 1 × 2 km. In this stage, a widespread Au anomaly in till was found 1 km SE of the known Vinsanmaa vein (Fig. 1 ). The vein cannot be the source of this anomaly because the known direction of ice flow is from the west. The Au content was high and it was assumed, that the anomaly was caused by local Au contents in bedrock. Therefore, detailed investigation was carried out. GEOLOGY
Most of the study area is albite diabase, which belongs to the Middle Jatulian Formation in the Per~ipohja schist area. The albite diabases occur as dykes conforming mostly to the layering of the surrounding bedrock. The main minerals are albite, amphibole, epidote and fine-grained quartz (Perttunen, 1983a). The albite is saussuritized and occasionally there is plenty of carbonate alteration. The texture is subophitic or ophitic and the diabase dykes are usually differentiated. The host rock is generally quartzite, in which the albite diabase occurs as intercalations. In the southern part of the area (Fig. 2). there is the Pisavaara quartzite, a clearly layered, grey or reddish orthoquartz-
GEOCHEMICAL GOLD PROSPECTING AT VINSANMAA, NORTHERN FINLAND
381
lOm , i N tll
4
~
3
5
6
.
S
t;t
i
i
0
100
I
200
I
I
300
400
I
500 m
Fig. 2. The bedrock at Vinsanmaa after Perttunen ( 1983a, b) and the diamond drilling results. A and B are the lines of the sampling with hydraulic hammer.
ite. The main mineral is quartz which occurs as roundish grains. The matrix material is fine-grained quartz, occasionally dolomite, and a little sericite (Perttunen, 1983b). The western part of the area is poorly known, because of the lack of outcrops. In the far west there are greenstones. The geomorphological landscape type is ground moraine. The bedrock is overlain by lodgement till, 5 to 12 m in thickness. The surface of the bedrock is usually preglacially weathered to a depth of 1 to 2 m. In the topographically lower parts the till is covered by peat deposits. Only one till bed occurs, and the direction of ice transport is from the west. SAMPLING
In regional mapping the till samples were taken with light percussion drill at l-m depth intervals to the attainable depth, at a density of one sampling
382
M. ,~YR,~,S 3 4
7362.800 Jc
4@ 5®
2@
10~
/
7
6"
A '@
B
/ x
@ Drilling s i t e
i
i
q
t
i
O
100
200
300
400
i
500 m
Fig. 3. Gold contents (ppb) in the - 0 . 0 6 m m fraction of weathered bedrock in the Vinsanmaa area.
point/42. In the second stage (Fig. 1 ), the samples were taken with percussion drill at 50-m intervals along lines 200 m apart. One sample was taken from the bottom part of the till layer, and another 1 to 2 m above the bottom sample. Also, if possible, samples from weathered bedrock were taken. In the third stage (Figs. 2, 3 and 4), sampling was done with hydraulic h a m m e r from till and weathered bedrock. Two lines were sampled across the anomaly found in the second stage. The sampling point distance varied from 50 to 10 m, with the 10-m interval being in the middle of the lines. In the final stage, vertical d i a m o n d drilling was carried out to depths of 5 to l 0 m in unweathered bedrock at 11 sites (Figs. 2, 3 and 4). ANALYSIS
The fine fraction ( - 0 . 0 6 m m ) of till and weathered bedrock, as well as the pulverized coarse fraction ( + 2.0 m m ) of weathered bedrock and the drill
GEOCHEMICAL GOLD PROSPECTING AT VINSANMAA, NORTHERN FINLAND
383
7362,B00~-
4@
21~ 6-
2-
5@ 10@
8@ ,;~2.
6@
g@
11@
'~ 3
J
B
@ Drilling site
t O
I 100
i 200
i 300
i 400
i 500 m
Fig. 4. Gold contents (ppb) in the - 0 . 0 6 m m fraction of till in the Vinsanmaa area.
core samples were analyzed in the GSF laboratory in Rovaniemi. The drill cores were usually analyzed at 1-m sections. The samples were analyzed for Co, Cu, Mn, Ni, Pb, Zn and Ag by flame atomic absorption (air-acetylene), Au and Pd by flameless atomic absorption after aqua regia leach. The methods of Au and Pd analyses are described by Kontas ( 1981 ) and Kontas et al. (1986). RESULTS AND DISCUSSION
The results of the second stage of till sampling are shown in Figure 1. There are two significant Au anomalies. The northernmost anomaly, some 100 m long, is caused by the known mineralized quartz vein. The highest Au contents in till in this anomaly are about 30 ppb. The most significant and widespread Au anomaly, 0.5 × 1 km in size, is in the central southeastern part of
384
M. ,~YRAS
the study area. The bedrock in study area is covered by only one till bed, transported from the west by the younger glaciation. The known quarz vein is probably not the source of the large anomaly. The highest Au content in till of this anomaly is 270 ppb. Beneath the till bed some samples of weathered bedrock were found, in which the Au contents vary from 23 to 85 ppb. It seems obvious that the Au anomaly in till has been caused by Au contents in local bedrock (Koivisto, 1984). The results of the third stage show that Au is enriched into the fine fraction of weathered bedrock (Table 1 ), whereas Au contents in the coarse fraction are low. Copper and cobalt are also enriched into the fine fraction of the weathered rock material, but this is not so clear as in the case of Au. The contents of Au, Cu and Co are much the same in the fine fractions of till and weathered bedrock as seen as median values in Table 1. On both lines (Figs. 3 and 4) the two highest Au contents (240 and 250 ppb ) are in weathered rock, which has been interpreted as albite diabase. The highest Au content in till is on the line B at the same point as the high content in weathered bedrock. The highest Cu contents are also in the fine fraction of weathered albite diabase. The Cu anomalies are, however, larger than the Au anomalies. The highest Co contents normally coincide with high Cu contents. The results indicate that the Au anomaly has its origin in the local bedrock. However, this study does not show the mode of occurrence of Au in the bedrock of the area. In 1986, the Geophysical Department of the GSF made magnetic and VLF-R measurements in the study area and on one line acrossing the known quartz vein. The anomaly patterns are in both cases much the same, the levels being very close to one another. Therefore, it was assumed that other Au mineralization like the known quartz vein could exist in the study area. In the final stage of the investigations, the diamond drilling, anomalous Au contents were found only in drill hole No. 6 (max. 420 ppb), which penetrates the albite diabase with a large number of narrow (about 10 cm) quartz veins (Fig. 5 ). In the upper part of the diabase there is saussuritization, carTABLE 1 The average contents (Y) and medians (Md) of Au, Co and Cu in till (the - 0 . 0 6 m m ) and in the fine ( - 0 . 0 6 m m ) and the pulverized coarse ( + 2 m m ) fraction of weathered bedrock in the Vinsanmaa area. Au(ppb)
Till Weathered bedrock (fine) Weathered bedrock (coarse)
2.6 16.0 0.9
Co(ppm)
Cu(ppm)
Md
~
Md
Y
Md
2.5 3.2 1.0
21.9 26.5 25.3
18.5 17.7 10
76.2 134.2 98.4
48 60 20
GEOCHEMICALGOLDPROSPECTINGATVINSANMAA,NORTHERNFINLAND
Q U A R T Z VEIN
Au ppb
Cuppm
420
3370
20
503
20
334
20
203
40
569
<10
9
385
ALBITE DIABASE OPHITIC SAUSSURITIZATION PLENTY OF PYRITE
Q U A R T Z VEIN ALBITE DIABASE C A R B O N A T E ALTERATION PYRITE
QUARTZ VEIN ALBITE DIABASE ALTERED PYRITE
Q U A R T Z VEIN ALBITE DIABASE LOW PYRITE CONTENT
I
QUARTZ VEIN ALBITE DIABASE SAUSSURITIZATION
I <10
2
Fig. 5. The rock types and Au and Cu contents in drill hole number 6 in the Vinsanmaa area.
bonate alteration and a great deal o f pyrites. The highest Au content is in the upper part o f the diabase. Also at a depth o f 16 to 17 m there is a slight increase in Au contents. The highest Cu contents coincides the highest Au contents. Also in hole No. 3 there is a slight increase in Au contents. The results o f diamond drilling shows that in the Vinsanmaa study area there are no other Au occurrences like the previously known mineralized vein. There is a clear increase o f Au contents in contact zones o f the diabase, and the Au is associated with pyrites. The widespread Au anomaly in till resembles the contents in weathered bedrock and has been caused principally by weathering o f diabase bedrock.
REFERENCES Koivisto, T., 1984. Geokemialliset tarkistustutkimukset Per~ipohjan liuskealueella: Moreenigeokemialliset kultatutkimukset Kivimaan ja Vinsan tunnettujen Cu-Au-juonimuodostumien ymp~iristSss~i. Rep., Arch. Geol. Surv. Finl., Rovaniemi, 19 pp. (in Finnish) (unpubl.).
386
M. AYRAS
Kontas, E., 1981. Rapid determination of gold by flameless atomic absorption spectrometry in the ppb and ppm ranges without organic solvent extraction. Atomic Spectros., 2: 59-61. Kontas, E., Niskavaara, H. and Virtasalo, J., 1986. Flameless Atomic Absorption Determination of Gold and Palladium in Geological Reference Samples. Geostandard Newslett., 10: 169-171. Manner, R. and Koivisto, T., 1981. Estitutkimusraportti karttalehden 2633 (Koivu) alueelta. Rep. The archieves of the Geological Survey of Finland, Rovaniemi, 22 pp. (in Finnish) (unpubl.). Perttunen, V., 1983a. Per~ipohjan liuskealueen vulkaniiteista. Vulkaniittisymposio, Pohtimolampi 3.-4.3.1983. Unpublished report in Finnish. Arch. Geol. Surv. Finl., Rovaniemi, 6 pp. ( in Finnish ) (unpubl.). Perttunen, V., 1983 b. Per~ipohjan etel~iosan geologia. Thesis, The University of Helsinki. 36 pp. (in Finnish) (unpubl.). Rouhunkoski, P. and Isokangas, P., 1974. The copper-gold vein deposit of Kivimaa at Tervola, N-Finland. Bull. Geol. Soc. Finl., 46: 29-35.