North Finland Unit
Q27/2007/45
Rovaniemi
18.12.2007
Petrophysical laboratory measurements
from the drill cores of the Sakiatieva gold
deposit at Sodankylä
Pertti Turunen and Veikko Keinänen
Susceptibility (SI)
10
0
10
-1
10
-2
10
-3
10
-4
Gold [ppb]
No data
Au < 20
20 Au < 40
40 Au < 60
60 Au < 80
Au 80
2500
2750
3000
Density (kg/m3)
3250
3500
GEOLOGICAL SURVEY OF FINLAND
DOCUMENTATION PAGE
Date / Rec. no.
18.12.2007
Authors
Type of report
Pertti Turunen and Veikko Keinänen
Archive report
Commissioned by
Title of report
Petrophysical laboratory measurements from drill cores of the Sakiatieva gold deposit at Sodankylä
Abstract
The report represents the petrophysical properties measured from the drill cores of the Sakiatieva gold deposit at
Sodankylä. The data are considered from the viewpoint of the variation of rock type and of the content of chemical
elements. The variation of density, magnetic susceptibility, intensity of remanent magnetization, and Q value does
not unambiguously classify rock types into separate units. In the same way, the correlations between the physical
properties and the analysed elemental contents are so low that the elements explain only partly the physical property variation. Obviously a major part of the variation of the physical properties is caused by the variation of rock
structure. The densities of ore containing rocks are lower than the densities of other rocks, and the magnetic properties of ore containing rocks are higher than those of other rocks.
Keywords
Petrophysical properties, gold
Geographical area
Finland, Lapland Province, Sodankylä Commune, Sakiatieva
Map sheet
3741 04
Other information
Report serial
Archive code
Q27/2007/45
Total pages
Language
14 + 5 appendices
English
Price
Confidentiality
Public
Unit and section
Project code
North Finland Unit
2901005
Signature/name
Signature/name
Pertti Turunen
Veikko Keinänen
GEOLOGIAN TUTKIMUSKESKUS
KUVAILULEHTI
Päivämäärä / Dnro
18.12.2007
Tekijät
Raportin laji
Pertti Turunen ja Veikko Keinänen
Arkistoraportti
Toimeksiantaja
Raportin nimi
Petrophysical laboratory measurements from drill cores of the Sakiatieva gold deposit at Sodankylä
[= Petrofysikaaliset laboratoriomittaukset Sodankylän Sakiatievan kultaesiintymän kairansydämistä]
Tiivistelmä
Raportissa esitellään Sodankylän Sakiatievan kairasydämistä tehtyjä laboratoriomittaksia. Tuloksia tarkastellaan
kivilajivaihtelun ja kemiallisten alkuainepitoisuuksien kannalta. Tiheys-, suskeptiivisuus-, remanenssi- ja Königsbergerin suhdevaihtelu ei luokittele kivilajeja yksikäsitteisesti omiksi yksiköikseen. Samoin petrofysikaalisten
ominaisuuksien ja analysoitujen alkuainepitoisuuksien väliset korrelaation ovat niin pieniä, että alkuaineet selittävät vain osan petrofysikaalisten ominaisuuksien vaihtelusta. Ilmeisesti suuri osa petrofysikaalisten ominaisuuksien
vaihtelusta aiheutuu kivilajien rakenteen vaihtelusta. Malmipitoisten kivien tiheydet ovat taustaa matalammat ja
magneettiset ominaisuudet korkeammat.
Asiasanat (kohde, menetelmät jne.)
Petrofysikaaliset ominaisuudet, kulta
Maantieteellinen alue (maa, lääni, kunta, kylä, esiintymä)
Suomi, Lapin lääni, Sodankylä, Sakiatieva
Karttalehdet
3741 04
Muut tiedot
Arkistosarjan nimi
Arkistotunnus
Q27/2007/45
Kokonaissivumäärä
Kieli
14 + 5 liitettä
Englanti
Hinta
Julkisuus
Julkinen
Yksikkö ja vastuualue
Hanketunnus
Pohjois-Suomen yksikkö
2901005
Allekirjoitus/nimen selvennys
Allekirjoitus/nimen selvennys
Pertti Turunen
Veikko Keinänen
Contents
Documentation page
Kuvailulehti
1
INTRODUCTION
1
2
MEASUREMENTS
2.1 General
2.2 Density
2.3 Susceptibility
2.4 Intensity of remanent magnetization
2.5 Q value
1
1
1
1
2
2
3
DATA
2
4
PHYSICAL PROPERTIES OF MAIN ROCK TYPES
3
5
PHYSICAL PROPERTIES AND CHEMICAL ANALYSES
8
6
PHYSICAL PROPERTIES OF GOLD CONTAINING ROCKS
10
7
SECTION THROUGH DRILL HOLES R258 – R259 AS AN EXAMPLE
13
8
CONCLUSIONS
14
LITERATURE
14
1
1
INTRODUCTION
This report represents data on physical properties of the drill cores from 26 holes drilled at the
Sakiatieva gold occurrence, Sodankylä, northern Finland. The core samples were from holes
drilled in 2004 – 2006. The petrophysical measurements were done in 2007 at the petrophysical
laboratory, and the chemical analyses at the chemical laboratory of GTK at Rovaniemi. A total
of 2412 petrophysical samples were measured. In addition to the petrophysical data, some correlations and statistics are presented as well considerations on the sources of the data variations.
2
2.1
MEASUREMENTS
General
The petrophysical properties of the drill core samples from 26 holes were measured in laboratory
conditions at Rovaniemi. The suite consisted of the measurement of density, magnetic susceptibility, and the intensity of remanent magnetization. The samples were taken at every full depth
meter where possible. If the rock at this depth was missing or was too broken, or if the distance
to the nearest solid sample exceeded ~20 cm, the depth was rejected and the next full meter was
considered. The measured samples were 5 to 10 cm in length. On the average, the volume of a 32
mm diameter sample is 50 – 60 cm3 and the mass is 150 – 200 g. The mass and volume differ if
the core diameter varies as the sample length remains unchanged.
Physical properties of rock samples are determined by educated and experienced personnel of the
petrophysics laboratory of the GTK. The measurement procedures are described in the Standard
Operating Procedures of the GTK petrophysics laboratory. A thorough description of the operations is documented by Puranen & Sulkanen (1985) and Puranen et al. (1993).
2.2
Density
Density is measured by using the Archimedes submersion method. A standard sample is measured every morning to test the scales, and another standard of 1000.0 grams is weighed twice a
month. First the sample is weighed in air and then submerged in water. The density of water depends slightly on the temperature. The water temperature is read in the morning and fed into the
computer, and the computer demands a new value after 41 samples have been measured. The
water is changed when it gets dirty and at all events every week. The mass of the sample is
measured five times under computer control and the standard deviation is calculated. If the standard deviation is between preset limits, the average of the measured weighs is accepted as the
result. The dimension of density is expressed in kg/m3. The accuracy of density determinations is
better than 5 kg/m3.
For a detailed description of density measurements see Puranen (1992).
2.3
Susceptibility
The magnetic susceptibility is measured by using an AC bridge. The frequency of the circuit is
1024 Hz. The sample is placed inside the coil and the system subtracts the background susceptibility when the coil is empty. The susceptibility is scaled by the volume of the sample and demagnetization effects are approximated by a cylinder model. Susceptibility values are expressed
as SI units and they are listed and stored as μSI units. The minimum measurable susceptibility
value is 10 μSI or 10*10-6 SI. Negative (diamagnetic) susceptibilities are occasionally measured.
Quartz is the most common diamagnetic mineral is quartz.
For a detailed description of susceptibility measurements see Puranen et al (1992).
2
2.4
Intensity of remanent magnetization
The intensity of remanent magnetization (or shortly remanence) is measured by a fluxgate element. The sample is placed and supported in the middle of a plastic box. The box is placed inside
a μ-metal cylinder that acts as a shelter against the Earth´s magnetic field. The sample is measured in six directions according to a preset scheme. The dimension of remanent magnetization is
A/m and it is listed and stored as mA/m.
For a detailed description of remanence measurements see Puranen et al (1992).
2.5
Q value
Q value or Königsberger ratio is not a measured quantity but a number calculated from remanence and susceptibility. Q relates the intensity of remanent magnetization to susceptibility so
that it shows the strength of remanence as a causer of magnetic anomalies in relation to susceptibility. E.g. if Q value is unity, remanence is equally strong in causing magnetic anomalies as
susceptibility. Königsberger ratio is defined as Q = J/κ/41, where J is intensity of remanence as
A/m, κ is susceptibility as SI-unit, and 41 is the prevailing Earth’s magnetic field strength (in
Finland 41 A/m). Q value is a dimensionless quantity. High Q values are connected to thin grain
size of ferromagnetic minerals.
3
DATA
In the following table, the column marked with “Bottom depth (m)” means the depth of the lowermost measured sample. If this differs considerably from the number of measurements, either
the overburden has been thick or a number of samples have been missing due to voids or broken
rocks.
Table 1. Petrophysical measurements from the drill cores of Sakiatieva.
Hole ID
M374104R252
M374104R253
M374104R254
M374104R255
M374104R256
M374104R257
M374104R258
M374104R259
M374104R261
M374105R262
M374105R263
M374105R264
M374105R265
M374105R266
M374106R267
M374106R268
M374106R269
M374106R270
M374106R272
M374106R273
M374106R274
M374106R275
No of measurements
143
99
114
56
79
120
76
85
52
88
105
17
111
37
83
61
99
87
55
117
138
133
Bottom depth (m)
149
110
128
68
91
131
95
104
70
100
111
45
118
74
95
74
118
97
83
136
162
154
3
M374106R276
M374106R277
M374106R278
M374106R279
Σ
4
98
94
145
120
2412
131
116
157
134
PHYSICAL PROPERTIES OF MAIN ROCK TYPES
The rocks have been classified into seven groups. More than 80 % of the samples were basic
volcanites. Because alteration and ore minerals affect the physical properties, basic volcanites
have been divided into three units. Ore means the zone of gold occurrence. Table 2 shows the
measured petrophysical data.
Table 2. Median values of the measured physical properties of main rock types.
Rock type
Number
(-)
171
1348
495
107
169
90
32
2412
Phyllite
Basic volcanite
Altered basic volcanite
Altered basic volcanite + sulphides
Ore
Quartz sulphide rock
Scarn sulphide rock
All
Susceptibility (SI)
10
Density
(kg/m3)
2928
3003
2965
2954
2908
2890
2931
2986
Susceptibility
(SI)
0.00387
0.00114
0.00122
0.00356
0.00501
0.00400
0.00569
0.00126
Remanence
(A/m)
1.30
0.07
0.12
1.33
1.68
1.69
2.37
0.16
0
10
-1
10
-2
10
-3
10
-4
Basic volcanite
Altered basic volcanite
Altered basic volcanite + sulphides
Ore
Quartz sulphide rock
Scarn sulphide rock
Phyllite
2250
2500
2750
3000
Density (kg/m3)
3250
3500
3750
Fig. 1. Cross-plot showing susceptibility vs. density for main rock types.
Q value
(-)
8.1
1.6
2.5
7.1
8.0
8.7
10.1
3.1
Frequency
0.15
Frequency
0.15
Frequency
0.15
Frequency
0.15
Fraquency
0.15
Frequency
0.15
Frequency
4
0.15
0.1
Phyllite
0.05
0
Basic volcanite
0.1
0.05
0
Altered basic volcanite
0.1
0.05
0
0.1
Altered basic volcanite
with ore
0.05
0
Ore
0.1
0.05
0
0.1
Quartz sulphide
rock
0.05
0
Scarn sulphide rock
0.1
0.05
0
2500
2750
3000
Density (kg/m3)
3250
3500
Fig. 2. Density histograms of main rock types.
The histograms in Figures 2 - 5 show that the variation within each rock group is bigger than between the groups. This means that none of the measured properties can unambiguously be used
to classify the core samples into rock types. The ultimate goal would be to be able to separate ore
containing rocks from other rocks, but this is obscured by overlapping distributions.
The density histograms show to kinds of density distribution; a narrow peak for basic volcatines
and wide, flat and disconnected distribution for all other rocks. Alteration causes density of basic
volcanites to go lower, and introduction of ore minerals enhances the effect.
Frequency
0.2
0.15
0.1
0.05
0
Phyllite
Frequency
0.2
0.15
0.1
0.05
0
Basic volcanite
Frequency
0.2
0.15
0.1
0.05
0
Altered basic
volcanite
Frequency
0.2
0.15
0.1
0.05
0
Altered basic volcanite
with ore
Frequency
0.2
0.15
0.1
0.05
0
Ore
Frequency
0.2
0.15
0.1
0.05
0
Quartz sulphide rock
Frequency
5
0.2
0.15
0.1
0.05
0
Scarn sulphide rock
10
-4
10
-3
-2
10
10
-1
Susceptibility (SI)
Fig. 3. Susceptibility histograms for main rock types.
In susceptibility the paramagnetic peak at ~10-3 SI is pronounced for basic volcanites. Alteration
increases susceptibility slightly. The ferromagnetic parts of the histograms for phyllites and all
ore containing rocks look very similar which means that all these rocks contain some magnetite.
Phyllites have the common distribution signature with ore containing rocks.
Frequency
Frequency
Frequency
Frequency
Frequency
Frequency
Frequency
6
0.1
Phyllite
0.05
0
0.1
Basic volcanite
0.05
0
0.1
Altered basic volcanite
0.05
0
Altered basic volcanite
with ore
0.1
0.05
0
Ore
0.1
0.05
0
Quartz sulphide rock
0.1
0.05
0
Scarn sulphide rock
0.1
0.05
0
10
-2
-1
10
0
10
Intensity of Remanence (A/m)
10
1
10
2
Fig. 4. Remanence histograms for main rock types.
The intensity of remanent magnetization of phyllites and ore containing rocks have almost identical distributions. Alteration does not seem to affect the remanence.
Frequency
Frequency
Frequency
Frequency
Frequency
Frequency
Frequency
7
0.1
Phyllite
0.05
0
0.1
Basic volcanite
0.05
0
0.1
Altered basic volcanite
0.05
0
0.1
Altered basic volcanite
with ore
0.05
0
0.1
Ore
0.05
0
Quartz sulphide rock
0.1
0.05
0
Scarn sulphide rock
0.1
0.05
0
10
-1
10
0
10
1
10
2
Königsberger Ratio (-)
Fig. 5. Q value histograms for main rock types.
The Q values for phyllites and ore containing rocks are again almost identical. The Q values of
most of the samples are around 10 which means that remanence must be taken into consideration
in magnetic interpretation. As a whole, the graphs of remanence and Q value have a lot in common.
The effective susceptibility, or the combined effect of susceptibility and remanence to cause
magnetic anomalies, is almost an order of magnitude higher for ore containing rocks than for basic volcanites. Only the overlapping of the effective susceptibility of phyllites with ores may
cause shadowing effects. In the next graph the distribution of the effective susceptibility of the
seven rock groups is represented as box-whisker plots. The graphs show the min, max, median,
8
Effective susceptibility (SI)
and lower and upper quartiles for each rock type. The high Q values of ore containing rocks
make it possible to make a distinction between them and basic volcanites in magnetic field mapping. Alteration has a minor effect on effective susceptibility.
10
1
10
0
10
-1
10
-2
10
-3
10
-4
Phyllite
BV
ABV ABV + sulphides Ore
QSR
SSR
Fig. 6. Effective susceptibility of main rock types.
5
PHYSICAL PROPERTIES AND CHEMICAL ANALYSES
Several elements, including Ag, Al, As, Au, B, Ba, Bi, Ca, Cd, Co, Cr, Cu, Fe, La, Li, Mg, Mo,
Na, Ni, P, Pd, Pb, Pt, Sb, Sc, Se, Si, Sr, Te, Th, Ti, V, Y, and Zn, were analyzed in the GTK
Geolaboratory (Keinänen et al 2007). For the following examination Al, Ba, Ca, Co, Cr, Cu, Fe,
K, Mg, Mn, Ni, P, S, Sc, Sr, Ti, V, Y, and Zn are considered versus each other and the measured
physical properties. Some of the elements were excluded due to very low percentage levels or
due to low number of analyses. Gold is discussed separately in the next chapter.
The following table shows the correlation coefficients between each of the analysed elements
and the physical properties. Because of large size the matrix has been split into two.
Table 3. Correlations between physical properties and chemical analyses.
ρ
κ
J
Q
Al
Ba
Ca
Co
Cr
Cu
Fe
K
Mg
ρ
κ
J
Q
Al
Ba
Ca
Co
Cr
Cu
Fe
K
1
0.321
0.165
-0.009
-0.085
0.030
0.190
0.096
0.009
0.039
0.081
-0.092
-0.065
1
0.800
-0.107
0.048
-0.113
0.080
0.422
0.360
0.241
0.374
0.078
0.349
1
0.075
-0.016
-0.150
0.006
0.416
0.265
0.279
0.372
0.116
0.240
1
-0.070
-0.036
-0.013
0.023
-0.007
0.087
0.053
-0.031
-0.036
1
0.432
0.068
-0.053
0.442
-0.270
-0.073
0.636
0.681
1
0.142
-0.217
-0.039
-0.238
-0.153
0.586
0.084
1
-0.049
-0.232
-0.079
0.103
0.148
-0.015
1
0.295
0.575
0.843
-0.055
0.176
1
0.035
0.064
0.197
0.782
1
0.677
-0.119
-0.098
1
0.070
0.038
1
0.382
9
Mn
Ni
P
S
Sc
Sr
Ti
V
Y
Zn
Mg
Mn
Ni
P
S
Sc
Sr
Ti
V
Y
Zn
0.106
0.075
0.148
0.037
-0.349
0.162
0.076
-0.349
-0.317
0.058
0.209
0.314
-0.276
0.382
-0.127
0.133
-0.239
0.046
0.023
-0.069
0.025
0.320
-0.342
0.435
-0.047
0.033
-0.260
0.130
0.121
-0.088
-0.009
0.017
-0.049
0.058
-0.038
-0.019
-0.050
0.007
0.013
-0.018
0.166
0.163
0.073
-0.240
0.366
0.156
0.306
0.077
-0.192
0.124
0.265
-0.092
0.278
-0.309
0.189
0.269
0.472
-0.054
-0.135
0.218
0.632
-0.130
0.241
-0.052
-0.004
0.774
0.221
-0.147
-0.039
0.053
0.103
0.451
-0.352
0.787
-0.087
-0.016
-0.322
0.179
0.208
-0.024
0.032
0.536
-0.514
0.129
-0.096
-0.163
-0.391
-0.025
-0.318
-0.080
0.013
0.237
-0.295
0.689
-0.008
-0.063
-0.282
0.288
0.435
0.094
0.245
0.308
-0.235
0.851
0.075
0.102
-0.161
0.332
0.447
0.039
Mg
Mn
Ni
P
S
Sc
Sr
Ti
V
Y
Zn
1
0.158
0.420
-0.319
-0.019
0.168
-0.018
-0.157
0.041
-0.260
-0.037
1
0.047
0.024
0.091
0.087
0.689
0.125
-0.055
-0.049
0.132
1
-0.585
0.278
-0.108
-0.060
-0.327
0.045
-0.083
-0.067
1
-0.385
0.001
0.196
0.637
-0.222
-0.002
0.127
1
0.008
-0.017
-0.371
0.347
0.429
-0.067
1
0.032
0.199
0.589
0.404
0.099
1
0.204
-0.123
-0.023
0.109
1
-0.042
-0.019
0.222
1
0.681
0.077
1
0.078
1
0.191
0.084
0.049
-0.067
0.437
0.213
0.393
0.230
0.045
0.131
The chemical analyses vs. density, susceptibility, intensity of remanence and Q ratio are represented in appendices 1 to 4. Density is linear but for all the others logarithms are used. LMS
(Least Mean Square) lines are added to the graphs.
Density
Susceptibility
Remanence
Q value
0.5
0.4
Correlation coefficient
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
Al
Ba
Ca
Co
Cr
Cu
Fe
K
Mg Mn
Ni
P
S
Sc
Sr
Analysed elements
Fig. 7. Correlation coefficients between physical properties and chemical analyses.
Ti
V
Y
Zn
10
Table 3 and the graph in Figure 7 show that the correlations between the measured physical
properties and the analysed elements are rather low. Density correlates negatively with Sc, V and
Y. Correlations with the metals Co, Cr, Cu, Fe, Ni, Ti and Zn are positive but so low that structural properties of the rocks easily shadow their effects.
For susceptibility there are more rather strong correlations with some metals and with sulphur.
The same applies to the intensity of remanence – its correlation coefficient with susceptibility is
as high as 0.8. The combined effect of susceptibility and remanence, as noted in Figure 6, makes
the magnetic method effective for ore prospecting in the area.
The Königsberger ratio does not correlate with any of the measured elemental abundances. The
coefficient varies between -0.1 and +0.1.
6
PHYSICAL PROPERTIES OF GOLD CONTAINING ROCKS
The content of gold does not necessarily cause any anomalies in the physical properties of rocks
but it may be useful to see if there exist correlations between physical properties and gold containing rocks. The gold content has been divided into five classes as one can see from Table 4
and Figure 8.
Table 4. Median values of physical properties in five gold content classes.
Au class
(ppb)
All
<20
20≥Au<40
40≥Au<60
60≥Au<80
Au≥80
Au content
(ppb)
10
26
48
69.5
205
No
(-)
2576
835
188
57
36
179
Density
(kg/m3)
2981
2978
2956
2938
2936
2929
Susceptibility
(SI)
0.00130
0.00159
0.00383
0.00416
0.00409
0.00041
Remanence
(A/m)
0.19
0.38
1.38
1.29
1.20
1.46
Q value
(-)
3.29
4.88
7.27
7.47
7.56
7.46
Most of the points cluster near the paramagnetic-ferromagnetic boundary at ~10-3 SI. The distribution of the points in various gold classes is rather scattered although the susceptibility value of
10
Susceptibility (SI)
10
Fig. 8. Cross-plot showing
susceptibility vs. density
for various gold content
classes.
10
0
Au [ppb]
No data
Au < 20
20 Au < 40
40 Au < 60
60 Au < 80
Au 80
-1
-2
10
-3
10
-4
2500
2750
3000
Density (kg/m3)
3250
3500
11
the red points tend to be higher than that of other points.
In the graphs in Figures 9 to 12 the median of each measured property is shown for five gold
content classes. Density shows two peaks, one around 2750 kg/m3 and the other around 3000
kg/m3. The increase of gold does not increase density. For susceptibility the increase on gold
produces higher susceptibilities. Very similar behaviour is apparent with remanence, but for Q
value there seems not to be any correlation.
Fig. 10. Susceptibility histograms
for Au content classes.
0.10
All
0.05
0.00
0.10
Au < 20
0.05
0.00
0.10
20
Au < 40
40
Au < 60
60
Au < 80
Au
80
0.05
0.00
0.10
0.05
0.00
0.10
0.05
0.00
0.10
0.05
0.00
2500
Frequency Frequency Fraquency Frequency Frequency Frequency
Fig. 9. Density histograms for Au
content classes.
Frequency Frequency Fraquency Frequency Frequency Frequency
The variation of the media of gold content in each group and the corresponding physical properties is shown in Figure 13.
0.15
0.10
0.05
0.00
2750
3000
Density (kg/m3)
3250
3500
All
0.15
0.10
0.05
0.00
Au < 20
0.15
0.10
0.05
0.00
0.15
0.10
0.05
0.00
0.15
0.10
0.05
0.00
0.15
0.10
0.05
0.00
10
-4
20
Au < 40
40
Au < 60
60
Au < 80
Au
80
10
-3
Susceptibility (SI)
10
-2
-1
10
Frequency Frequency Fraquency Frequency Frequency Frequency
12
0.10
All
0.05
0.00
0.10
Au < 20
0.05
0.00
0.10
20
Au < 40
40
Au < 60
60
Au < 80
Au
80
0.05
0.00
0.10
0.05
0.00
0.10
0.05
0.00
0.10
0.05
0.00
10
-2
-1
0
10
10
10
Intensity of Remanence (A/m)
1
2
10
Frequency Frequency Fraquency Frequency Frequency Frequency
Fig. 11. Intensity of remanence histograms for Au content classes.
0.15
0.10
0.05
0.00
All
0.15
0.10
0.05
0.00
Au < 20
0.15
0.10
0.05
0.00
0.15
0.10
0.05
0.00
0.15
0.10
0.05
0.00
0.15
0.10
0.05
0.00
10
-1
20
Au < 40
40
Au < 60
60
Au < 80
Au
80
10
0
10
1
Q value (-)
Fig. 12. Q value histograms for Au content classes.
10
2
13
10
2970
Q value (-)
1
2980
10-1
2950
2940
10-2
2930
-3
2920
Susceptibility (SI)
Density (kg/m3)
2960
Remanence (A/m)
0
10
10
0
0.05
0.1
Au (ppm)
0.15
0.2
0.25
Fig. 13. Relationship between gold content groups and physical properties.
The horizontal axis shows the median value of the gold content - the five dots represent the medians of the five groups - of the analyses that fall between the boundaries given in table 3. The
locations of the dots on the vertical axes similarly give the median values of density, susceptibility, remanence, and Q value. Density falls with growing Au content, but all the other properties
show slight increase with increasing Au content.
7
SECTION THROUGH DRILL HOLES R258 – R259 AS AN EXAMPLE
Appendix 5 shows petrophysical data from a section defined by two gold containing drill holes.
At the top in the middle and on the right the petrophysical properties along with Au content is
shown for total lengths of the holes R258 and R259. At the bottom a closer look at the mineralized zone is given. Note the direction of the x axes - depth runs from right to left.
The holes intersect a mineralized zone containing up to 8 ppm gold and increased contents of
several other metals. The zone, extending from 45 to 58 m in R258, is not clearly visible in density even if the density level is rather high, ~3000 kg/m3. Near the gold maximum the density
shows a local minimum. All the magnetic properties show similar patterns with each other.
In R259 the mineralized zone is between 75 and 85 m. Density, susceptibility, and remanence all
show positive anomalies here with the exception of negative susceptibility at 82 m. There are,
however, similar positive anomalies with no gold content.
Gamma radiation intensity was measured from the core samples of R359 in laboratory. After removing the background radiation the readings were scaled with the mass of the sample to yield
the specific activity. This makes it possible to compare the activities of various samples. As one
can see from the graph, the radiation levels are very low. Negative values are the combined effect of the very low radiation level and the statistical nature of radioactive radiation.
14
8
CONCLUSIONS
Density is not very suitable in prospecting the Sakiatieva occurrence. The variation of density
within each rock type is bigger than between separate rock types. The correlation between density and the analysed elements is low and the most notable correlation coefficients are negative.
This suggests that structural properties of rocks are the reasons behind density variation. Especially the negative correlation between density and Au content is notable.
Susceptibility of ore containing rocks is highest but causes overlapping effects with phyllites.
The correlation coefficients with analysed elements are mostly positive and explain more of the
variation than did density. Again, gold content correlates positively with susceptibility. Susceptibility, or the magnetic method, is a suitable tool in prospecting for gold bearing rocks.
The intensity of remanence correlates strongly with susceptibility and thus what is said about
susceptibility applies to remanence, too. Q value has very little correlation with any rock type or
element the good correlations of susceptibility and remanence disappear through the division
process.
Electric and radioactive methods would possibly have been even better than susceptibility in detecting and examining ore and especially gold bearing rocks. Unfortunately all the drill holes
were blocked and no downhole loggings could be made.
LITERATURE
Keinänen, V., Pulkkinen, E., Ojala, J.V., Salmirinne, H., Chernet, T., Räsänen, J., Turunen, P.
and Sarapää, O. 2007. Report on the Sakiatieva gold prospect: claims (Ruosselkä8: 7300/1 and
Sakiatieva 7392/1) Sodankylä, Finland. 47 p., 3 app. GTK, archive report, M06/3741/2007/10/60
Standard Operating Procedures of the GTK petrophysics laboratory.
http://document.gtk.fi/docushare/dsweb/View/Collection-6052
Puranen, R. & Sulkanen, K. 1985. Technical description of microcomputer-controlled petrophysical laboratory. 257 p. GTK, archive report, Q15/27/85/1.
Puranen, R., Sulkanen, K., Poikonen, A., Nissinen, R., Simelius, P. & Harinen, L. 1993. User's
manual for computerized petrophysics laboratory. 50 p., 4 app. GTK, archive report,
Q19.1/27/93/1.
Puranen, R. 1992. Tiheysmääritykset AT-mikrotietokoneen ohjauksessa (Density determinations
under AT micro computer control). 4 p., 2 app. GTK, archive report, Q15/27.1/92/1.
Puranen, R., Sulkanen, K. & Nissinen, R. 1992. Suskeptibiliteettimittaukset ATmikrotietokoneen ohjauksessa (Susceptibility determinations under AT micro computer control).
6 p., 11 app. GTK, archive report, Q15/27.2/92/1.
Puranen, R., Nissinen, R. & Sulkanen, K. 1992. Remanenssimittaukset AT-mikrotietokoneen
ohjauksessa (Remanence determinations under AT micro computer control). 8 p., 9 app. GTK,
archive report, Q15/27.2/92/2.
Chemical analyses vs. density.
10000
200
0
0
3000
3500
50000
0
2500
3
kg/m
kg/m
500000
400000
ppm
ppm
5000
2500
3000
3500
2500
3
3000
kg/m
3000
Ni
ppm
2000
0
3000
3500
2500
0
ppm
800
4000
2000
3000
3500
3000
kg/m3
3500
ppm
3000
3500
200
Sc
2500
3000
3500
Y
200
40
0
3500
Zn
150
100
0
2500
3000
kg/m3
3500
2500
3000
kg/m3
2500
3000
kg/m3
kg/m3
50
3000
100
0
250
Sr
150
10
3500
3500
kg/m
0
3000
3000
3
0
20
kg/m3
2500
50
V
2500
2000
15
2500
Mn
3000
5
60
0
2500
4000
kg/m
200
0
5000
0
kg/m3
400
kg/m
3
S
3500
1000
2500
20
3000
3
50000
3500
600
2500
Mg
3
100000
ppm
Ti
3500
50000
0
kg/m3
1000
3000
kg/m
25000
200000
3000
0
2500
150000
kg/m3
0
10000
0
2500
500
100000
kg/m
2000
100
75000
2500
1000
3
20000
3500
P
200
3500
Cr
1500
3
K
3
1000
1000
3000
30000
200000
3000
ppm
Fe
0
kg/m
ppm
40000
100000
2500
6000
2500
kg/m
300000
0
8000
3500
3
ppm
Cu
7500
4000
3000
ppm
10000
100000
ppm
2500
Co
300
ppm
400
2000
ppm
20000
600
Ca
ppm
30000
Ba
400
ppm
800
150000
ppm
Al
ppm
ppm
40000
1000
ppm
50000
Appendix 1.
3500
3500
Chemical analyses vs. susceptibility
200
0
0
10
-3
-2
10
10
-1
10
-5
-4
10
(SI)
500000
Cu
ppm
ppm
-1
10
10
5000
40000
300000
200000
0
-4
10
10
-3
-2
10
10
-1
10
-5
-4
10
(SI)
-3
10
10
-2
3000
ppm
3000
2000
0
-5
-4
10
10
-3
-2
10
10
-5
-4
10
-3
10
100000
-5
-4
10
10
-2
2000
-3
-2
10
10
-1
-5
10
-4
10
10
-3
(SI)
-2
10
10
-1
5000
Mg
10
-3
-2
10
10
-5
-4
10
-3
10
10
-2
-1
10
10
-5
-4
10
-3
10
10
-2
-1
10
(SI)
-4
10
-3
(SI)
-2
10
10
-1
150
100
0
10
-5
-4
10
10
-3
(SI)
-2
10
10
-1
-3
10
10
-2
10
10
-2
10
-1
Sr
100
-5
10
-4
10
-3
10
(SI)
10
-5
-4
10
-3
10
(SI)
Zn
200
0
10
-4
10
150
250
40
-1
(SI)
50
-5
-5
200
(SI)
20
10
10
Sc
10
Y
10
0
10
-1
-2
2000
0
-4
10
1000
20
10
-3
10
3000
0
-5
-4
10
Mn
4000
0
10
-5
(SI)
15
60
0
10
(SI)
200
0
-1
10
50
-1
400
-2
5
10
600
10
50000
ppm
ppm
4000
10
100000
V
800
-3
10
50000
S
(SI)
Ti
-4
10
(SI)
150000
1000
6000
-5
10
0
200000
(SI)
8000
-1
75000
10
P
10
0
(SI)
2000
-1
0
0
0
10
10
500
25000
-1
1000
1000
-2
10
K
(SI)
Ni
-3
1000
100
10000
10
ppm
4000
10
20000
0
-5
-4
10
30000
100000
10
-5
200
(SI)
Fe
400000
2500
ppm
-2
(SI)
7500
ppm
10
ppm
10000
-3
10
ppm
-4
10
0
ppm
-5
10
50000
Cr
1500
ppm
10000
300
100000
ppm
400
2000
Co
ppm
ppm
20000
600
400
Ca
ppm
800
30000
150000
Ba
ppm
40000
ppm
1000
Al
ppm
50000
Appendix 2.
10
-2
-1
10
-1
Chemical analyses vs. intensity of remanence.
400
200
0
0
1
10
2
0
-2
10
10
-1
10
A/m
500000
Cu
ppm
ppm
1
10
2
-2
10
5000
40000
300000
200000
0
-1
10
0
10
1
10
2
-2
10
10
-1
10
A/m
10
0
10
1
10
3000
ppm
3000
2000
0
-2
-1
10
0
10
1
10
2
-2
-1
10
10
0
10
1
10
Ti
-2
-1
10
2000
0
1
10
10
2
-2
-1
10
0
10
A/m
1
10
2
10
-2
-1
10
0
10
1
10
2
1
10
200
Sc
-2
10
-1
10
0
10
1
10
2
10
A/m
250
Y
40
-1
0
10
A/m
1
10
2
10
150
100
0
-2
10
-1
10
10
0
A/m
1
10
10
2
0
10
1
10
10
2
Sr
100
-2
10
-1
10
0
10
A/m
-2
10
-1
10
0
10
A/m
Zn
200
0
10
-1
10
150
50
-2
10
A/m
10
2
20
10
-2
10
0
10
10
2000
0
0
1
3000
0
10
2
Mn
4000
50
-1
10
0
20
10
1
10
1000
A/m
0
10
5000
5
-2
0
10
A/m
15
10
-1
10
A/m
200
0
-2
10
Mg
10
S
60
400
2
10
50000
ppm
ppm
4000
10
100000
2
600
1
10
50000
0
V
800
6000
0
10
A/m
0
A/m
1000
-1
10
75000
200000
A/m
8000
-2
10
150000
10
0
2
K
10
P
2000
10
0
25000
0
10
500
A/m
1000
1000
10
1000
100
100000
A/m
Ni
1
10
200
10000
2
ppm
4000
0
20000
0
-2
10
30000
100000
10
-1
10
Cr
1500
A/m
Fe
400000
2500
ppm
10
A/m
7500
ppm
0
ppm
10000
10
ppm
0
10
50000
ppm
-1
10
100000
ppm
-2
Co
300
ppm
10000
Ca
2000
ppm
600
400
ppm
ppm
20000
10
Ba
800
30000
150000
ppm
Al
40000
ppm
1000
ppm
50000
Appendix 3.
1
10
2
10
10
2
Chemical analyses vs. Q value.
0
10
10000
-3
-2
10
10
-1
10
0
10
1
10
Cu
ppm
-1
10
10
0
10
1
10
40000
300000
200000
100000
0
4000
101
10-3 10-2 10-1 100
3000
Ni
ppm
3000
2000
0
ppm
4000
2000
400
-3
-2
10
10
-1
10
0
10
1
ppm
1
10
5000
4000
0
0
10-3 10-2 10-1 100
101
101
-3
-2
10
10
-1
10
0
1
10
-3
-2
10
10
-1
10
0
1
10
10
1
Mn
101
Sr
100
0
101
Zn
150
100
0
10
0
50
200
0
10
10-3 10-2 10-1 100
Sc
250
40
-1
2000
150
10-3 10-2 10-1 100
Y
10
0
10
5
-2
10
3000
15
50000
-3
1000
50
10
10
Mg
20
20
0
10
0
10
10-3 10-2 10-1 100
S
60
600
-1
10
50000
101
100000
101
-2
10
75000
200
0
-3
10
0
V
800
6000
1
10
150000
1000
0
100000
10-3 10-2 10-1 100
P
10-3 10-2 10-1 100
Ti
0
0
0
ppm
8000
10
K
200000
2000
101
-1
500
25000
0
10-3 10-2 10-1 100
10
1000
100
10000
101
1000
1000
-2
10
20000
0
10-3 10-2 10-1 100
-3
30000
ppm
ppm
5000
-2
10
Fe
400000
2500
ppm
-3
500000
7500
ppm
0
200
ppm
0
ppm
200
ppm
10000
50000
Cr
1500
ppm
400
2000
Co
300
100000
ppm
ppm
20000
600
400
Ca
ppm
800
30000
150000
Ba
ppm
40000
ppm
1000
Al
ppm
50000
Appendix 4.
-3
10
-2
10
-1
10
0
10
1
10
10-3 10-2 10-1 100
101
R259
8
8
4
3250
3250
ρ
(kg/m3)
0
3000
2750
10
-2
10
-3
1
0
-2
Basic volcanics
60
Ore
40
20
Basic volcanics Saprock
-3
1
10
0
-1
0
20
0
-20
Bq/kg
80
-1
10
10
A
vo lter
lc ed
an b
ic as
s ic
100
su
lp
hi
de
-1
Q
ro ua
ck rtz
10
10
10
J
(A/m)
10
10
A
vo lter
lc ed
an b
i c as
s ic
J
(A/m)
10
2750
120
100
80
A
vo lter
lc ed
an b
ic as
s ic
Q
su ua
r
lp tz
hi
de
ro
ck
-1
3000
κ
(SI)
10
Appendix 5.
4
0
κ
(SI)
ρ
(kg/m3)
Au
(ppm)
R258
Au
(ppm)
Section through drill holes R258 – R259 (Keinänen et al 2007).
Ore
3250
3250
ρ
(kg/m3)
0
2750
J
(A/m)
10
-3
10
10
10
10
1
0
-1
10
-3
56
52
48
Depth (m)
44
40
-1
10-2
10
60
1
100
-1
10
-3
10
10
10-2
-1
10-2
-1
10
κ eff
(SI)
-1
-2
10
2750
κ
(SI)
10
Basic volcanics
3000
J
(A/m)
κ
(SI)
10
Altered basic
volcanics + sulphides
20
4
0
3000
40
8
Au
(ppm)
4
κ eff
(SI)
ρ
(kg/m3)
Au
(ppm)
8
60
Depth (m)
-3
95
90
85
80
Depth (m)
75
70
0
Saprock