Pekkarinen, 1979; Pekkarinen and Lukkarinen, 1991; Kohonen and Marmo, 1992; Karhu, 1993.
Otherwise lithostratigraphy and chronostratigra- phy of the Ho¨ytia¨inen area are not resolved Ko-
honen, 1995 but depositional ages from 2.1 to about 1.9 Ga are inferred.
The Suvasvesi area is characterized by the ‘Up- per Kaleva’ Kontinen and Sorjonen-Ward, 1991
or Western Kaleva Kohonen, 1995 a term adopted in this study greywackes that occur as
allochthonous units in thrust complexes charac- terized by associated ophiolites and related rocks
Koistinen, 1981 and references therein though evidence for local deposition upon Archaean
basement has also been noted Ward, 1987. The increase in metamorphic grade from east to west
Fig. 2 is seen as an increase in quartz veins and the onset of segregational banding quartz +
feldspar leading finally to migmatites.
The boundary zone BZ includes migmatitic sedimentary rocks Korsman et al., 1984 and a
1.93 – 1.91 Ga volcano-plutonic formation Lahti- nen, 1994 and references therein. The Svecofen-
nian is divided into the central Svecofennian including the Central Finland Granitoid Complex
CFGC and Bothnian Belt BB, and the south- ern Svecofennian including the Rantasalmi –
Haukivuori
area RH.
The tentative
sedimentation ages for the central Svecofennian, based on data available from the Tampere Schist
Belt Lahtinen, 1996 and references therein, are ]
1.91 and 1.89 – 1.87 Ga for rocks correlated to basement- and arc-related groups in the Tampere
Schist Belt, respectively. The southern Svecofen- nian, including the Rantasalmi – Haukivuori area,
is characterized by granite migmatites, which is a clear difference to the central Svecofennian,
boundary zone and Suvasvesi area, which are characterized by tonalite migmatites Korsman et
al., 1999 and references therein.
4. Results
Because lithostratigraphic division of sedimen- tary rocks is rarely available, division of sedimen-
tary rocks into different groups within domains is based mainly on lithotype and geochemical char-
acteristics. All elements analyzed have been used but the main weight has been put on the REE,
Th, Sc, Cr and major elements where the REE, Th and Sc are considered as most reliable ele-
ments in monitoring the average source composi- tion Taylor and McLennan, 1985; McLennan et
al., 1990. The arc-related upper central Sve- cofennian rocks of this study Fig. 2, not dis-
cussed in detail, show CaO, MnO, P
2
O
5
, Sr, Ba and Sb enrichment, which is characteristic of sed-
imentary rocks derived from high-K calc-alkaline to
shoshonitic volcanics
Lahtinen, 1996.
Strongly altered or mineralized samples are ex- cluded from discussion as are minor groups of
sedimentary rocks either having undefined origins or a large non-clastic component e.g. iron forma-
tions and carbonate rocks.
The group characteristics were also studied by using normalized diagrams Fig. 3. Archaean
sedimentary groups are normalized to Archaean crust AC1, autochthonous and allochthonous
groups to average Karelian craton KC1 and boundary zone and Svecofennian groups to West-
ern Kaleva WK1 Table 1. The AC1 is a first approximation of the average composition of Ar-
chaean crust in Finland at its present erosion level based solely on the data from the study area. The
granitoid-dominated nature of the exposed Ar- chaean part of the study area is seen in higher
LILE and LREE and lower MgO, Cr and Ni compared to the Late Archaean 3.5 – 2.5 Ga
restoration model for average juvenile upper con- tinental crust Table 4 in Condie, 1993. The
Karelian craton includes a large contribution from Palaeoproterozoic mafic dykes and volcanics
2.2 – 1.97 Ga; Vuollo, 1994 relative to the Ar- chaean crust average Fig. 3.
4
.
1
. Archaean sedimentary rocks The
Archaean metagreywackes
and mica
schistsgneisses have been divided into two main groups Ar1 – Ar2. The Ar1 rocks have a homo-
geneous composition indicating a thorough mix- ing of source components. The elevated CIA
Chemical Index of Alteration; Nesbitt and Young, 1982 shows the effects of weathering in
the source area and the REE, major and trace
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Table 1 Average chemical composition of estimated Archaean crust AC1 and Karelian craton KC1, and selected sedimentary rock groups non-migmatized, except groups
BZ1–BZ2
a
BZ1 Ar1
WK2 H1
WK1frag H2
WK1 H3
BZ2 KC1
AC1 N = 4
N = 8 N = 156
N = 129 N = 5
N = 9 N = 47
N = 5 N = 17
N = 11 N = 6
67.23 69.85
69.58 63.23
65.15 68.60
56.42 SiO
2
60.16 65.15
63.64 65.18
0.51 0.80
0.62 0.68
0.69 0.83
0.72 1.08
0.65 0.76
TiO
2
0.72 12.87
14.86 14.74
13.11 13.27
15.42 15.16
17.68 14.68
Al
2
O
3
15.15 15.19
5.20 4.95
4.93 6.64
6.05 7.90
9.24 6.60
6.27 FeO
4.71 5.73
0.06 0.08
0.07 0.07
0.07 0.08
0.08 0.11
0.10 0.08
0.08 MnO
5.19 2.34
2.52 2.26
2.33 3.23
2.84 4.29
2.81 3.55
2.91 MgO
1.46 2.22
2.42 2.36
2.34 1.68
2.59 CaO
0.87 1.46
4.06 3.39
4.24 1.24
1.98 2.98
2.76 2.84
2.92 2.93
3.89 2.37
Na
2
O 2.18
3.44 2.37
2.41 3.36
3.34 3.87
3.44 2.76
K
2
O 2.71
2.35 2.46
0.15 0.18
0.11 0.16
0.15 0.16
0.14 0.11
0.18 0.12
0.13 P
2
O
5
0.34 0.05
0.13 0.22
0.29 0.07
0.05 0.05
0.05 0.10
0.09 C
graf.
0.21 0.067
0.082 0.061
0.21 1.24
0.23 S
0.12 0.41
0.061 0.054
0.070 0.054
0.053 0.085
0.078 0.094
F 0.055
0.051 0.045
0.062 0.094
62.64 54.4
54.7 55.8
55.6 57.8
62.9 62.5
49.3 61.9
CIA 50.0
36.2 31.1
32.0 31.6
30.6 33.2
36.7 44.3
31.8 15.2
La ppm 23.4
71.2 62.2
63.2 62.9
60.9 65.4
73.2 86.5
63.4 32.7
Ce ppm 47.9
7.27 7.43
7.29 8.02
8.60 7.44
10.1 Pr ppm
5.67 4.12
7.42 8.23
21.5 27.9
26.7 27.3
26.6 28.9
31.4 37.1
27.3 Nd ppm
15.3 29.7
5.17 5.13
4.98 5.55
5.72 5.49
6.44 3.10
4.28 Sm ppm
4.90 4.76
1.14 1.02
0.96 1.06
1.03 1.15
1.13 1.44
1.07 0.94
0.91 Eu ppm
4.91 3.86
4.27 4.63
4.47 5.04
5.26 6.13
4.00 2.96
3.88 Gd ppm
0.66 0.68
0.66 0.75
0.73 0.73
0.90 Tb ppm
0.61 0.48
0.55 0.50
3.36 3.68
3.42 4.12
3.75 Dy ppm
5.01 2.40
2.76 2.95
3.36 4.21
0.66 0.73
0.68 0.79
0.71 0.79
1.00 0.58
0.67 Ho ppm
0.45 0.53
2.31 1.26
1.88 2.12
2.04 2.31
2.03 3.06
1.50 1.76
1.94 Er ppm
0.33 0.18
0.27 0.31
0.30 0.32
0.29 0.47
0.21 0.26
0.28 Tm ppm
1.79 2.16
1.95 2.19
1.94 2.23
3.13 Yb ppm
1.84 1.73
1.38 1.17
0.27 0.32
0.30 0.32
0.27 0.46
Lu ppm 0.18
0.21 0.25
0.28 0.35
570 489
508 613
704 348
712 Ba ppm
392 371
742 858
116 58.1
48.8 79.4
100 139
139 172
157 127
Cl ppm 52.2
14.1 30.0
16.8 14.1
14.4 21.3
18.9 30.2
18.8 32.0
Co ppm 21.7
110 106
104 137
120 238
172 Cr ppm
180 294
80.6 77.7
3.50 5.02
5.01 4.46
4.92 Hf ppm
5.10 3.78
3.63 3.53
4.63 3.91
10.2 9.20
9.13 11.2
12.2 9.75
14.6 5.74
b
8.70 Nb ppm
5.54 5.70
149 35.6
52.4 44.9
45.4 65.3
53.6 90.9
41.3 145
111 Ni ppm
138 84.0
138 82.5
89.1 117
122 135
74.0 84.5
104 Rb ppm
15.4 15.3
14.9 20.5
17.9 22.0
29.2 Sc ppm
16.3 21.9
15.0 11.4
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153 Table 1 Continued
BZ1 H1
KC1 H2
BZ2 H3
AC1 WK1
WK1frag WK2
Ar1 N = 11
N = 5 N = 9
N = 47 N = 4
N = 17 N = 6
N = 156 N = 5
N = 8 N = 129
147 247
250 223
275 326
Sr ppm 495
437 180
111 108
0.80 0.68
0.66 0.76
0.82 0.68
0.74 Ta ppm
0.64 0.42
b
0.41 0.40
8.72 8.51
10.8 8.93
8.54 9.27
10.9 12.5
7.59 4.60
Th ppm 7.59
2.56 1.82
1.98 2.00
1.88 2.76
1.64 1.22
1.91 U ppm
1.49 1.32
196 94.9
120 128
128 164
143 222
127 160
142 V ppm
26.6 15.3
23.2 23.7
22.4 26.5
23.1 30.2
17.2 20.9
24.4 Y ppm
105 83.7
83.5 115
109 154
153 Zn ppm
b
108 128
88.1 81.6
144 Zr ppm
217 162
208 203
193 202
155 161
190 150
0.082 0.067
0.044 0.061
0.055 0.053
0.059 Ag ppm
b
0.16 0.068
0.052 0.047
b
0.86 12.9
4.52 0.42
0.52 0.63
1.10 1.01
0.80 1.28
As ppm
b
6.53 0.52
0.34 0.31
0.40 0.79
Au ppb
b
1.00 0.78
1.05 0.47
0.73 0.42
0.31 0.10
0.034 0.12
0.15 0.21
0.080 0.079
Bi ppm 0.20
0.22 0.072
84.0 23.8
41.9 25.6
25.1 31.7
37.3 88.8
42.7 61.3
42.7 Cu ppm
b
1.71 3.88
0.79 0.26
0.31 0.39
0.27 1.0
Pd ppb 0.2
0.2 1.80
0.031 0.028
0.021 0.021
0.046 0.095
0.041 0.029
0.035 Sb ppm
0.037 0.036
0.56 0.053
0.22 0.13
0.13 0.15
0.20 0.45
0.075 0.31
0.15 Se ppm
28.2 42.2
25.0 12.7
13.5 16.7
22.6 49.6
9.46 Te ppb
9.56 47.4
a
WK1frag is the average of mica gneiss fragments in migmatites. Values in parentheses include many determinations below the detection limit C
graf
0.05 and Pd 0.2 ppm and show either the detection limit value or averages excluding values below detection limits.
b
One to two anomalous analyses have been excluded from some group averages.
elements indicate a more mafic source compared to local Archaean bedrock at the present erosion
level Figs. 4 and 5, and Table 1. The Ar2 samples show variable REE and have higher
CaO, Na
2
O and lower K
2
O, Cr and Rb compared to Ar1 see Fig. 4 for K
2
O and Cr. The lower CIA indicates less weathering relative to Ar1 and
low ThSc 0.09 – 0.17 favours a dominant mafic source.
4
.
2
. Cratonic co6er The Jatuli-type quartzites of this study show a
strong increase in K
2
O with decreasing SiO
2
Fig. 4, which is mainly due to variations in sericite
muscovite content. One subarkose contains fresh K-feldspar also seen in a lower CIA value but
otherwise high CIA is a characteristic feature. The sedimentary rocks in the Ho¨ytia¨inen basin are
classified into high- and low-Cr groups H1 and H3, respectively Fig. 4, Table 1. A distinct litho-
logical unit Huhma, 1975 of high-Cr rocks is classified as group H2 and a suspect group of
low-Cr rocks, possibly related to the Western Kaleva Kohonen, 1995, is classified as group
H4. Samples outside the Ho¨ytia¨inen area Fig. 2, but that occur in autochthonous position to Ar-
chaean dome rocks or are geochemically similar, are included in these groups. The H1 – H3 samples
include quartz-rich greywackes and more typically pelites showing thin layering from 1 – 3 mm to
1 – 2 cm with thin psammitic interlayers occurring locally. The variation in element abundances in-
side the H1 group is mainly explained by quartz dilution Fig. 4. There is evidence of weathering
in at least one component CIA 54 – 70 and a
Fig. 3. Major- and trace-element distributions in Karelian craton 1, Western Kaleva psammites WK1, Jatuli-type mafics and Kutsu-type granites normalized to Archaean Crust AC1 in Table 1. The Karelian craton KC1 and WK1 averages are from Table
1 and the averages for Jatuli-type mafics N = 21 and Kutsu granites N = 8 are from Lahtinen unpublished data.
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155 Table 2
Average chemical composition of selected sedimentary groups non-migmatized, except CF3 average including also mica gneiss fragments in migmatites
a
CF3 RH2mig
CF2 RH3lCr
CF1 RH4hCr
CF3mig RH1
RH2 N = 4
N = 4 N = 14
N = 5 N = 6
N = 6 N = 14
N = 7 N = 12
72.37 69.70
63.71 63.71
70.75 SiO
2
67.94 61.99
64.95 76.50
0.53 0.69
0.52 0.60
0.73 0.74
0.73 0.79
TiO
2
0.58 13.25
14.20 12.78
13.47 15.24
15.71 16.13
Al
2
O
3
17.84 11.75
3.78 4.56
5.97 6.33
5.25 7.18
4.51 FeO
3.78 5.77
0.07 0.03
0.06 0.07
0.08 0.09
0.05 0.06
0.08 MnO
2.78 1.38
1.56 2.21
3.04 2.92
2.30 3.17
2.05 MgO
1.91 2.13
1.88 1.94
2.44 CaO
2.04 0.89
1.23 0.52
2.91 2.54
2.97 2.94
2.59 2.57
2.18 Na
2
O 1.67
1.67 2.58
2.59 3.41
3.28 2.55
2.71 K
2
O 2.59
3.81 3.97
0.17 0.10
0.15 0.16
0.15 0.12
0.13 0.12
0.15 P
2
O
5
0.05 0.05
0.08 0.15
C
graf.
0.05 0.25
0.09 0.05
0.05 0.023
0.033 0.11
0.082 0.23
0.10 S
0.051 0.043
0.41 0.064
0.0488 0.052
0.064 0.075
0.076 0.085
0.12 0.052
F 55.1
56.4 54.6
54.8 58.0
58.8 CIA
64.8 62.3
68.8 47.6
37.9 34.2
37.0 37.9
44.8 30.7
La ppm 31.4
44.1 94.3
74.8 69.1
74.3 Ce ppm
63.2 86.9
88.7 75.8
62.5 10.5
8.69 8.16
8.79 7.34
Pr ppm 8.64
10.4 10.1
7.42 37.9
32.0 Nd ppm
30.3 27.5
32.1 38.0
38.4 32.3
27.3 6.53
5.87 5.61
5.95 5.23
7.29 5.63
Sm ppm 4.98
6.85 1.12
0.94 1.21
1.17 1.10
1.10 1.33
1.19 1.06
Eu ppm 5.59
5.28 5.15
5.46 Gd ppm
4.32 6.08
6.46 5.03
4.44 0.80
0.75 0.75
0.80 0.65
0.63 Tb ppm
0.71 0.96
0.89 3.44
3.30 3.99
3.86 3.97
4.33 4.80
5.05 3.80
Dy ppm 0.67
0.64 0.81
0.77 0.78
0.89 0.94
0.95 0.72
Ho ppm 2.32
2.27 2.19
2.64 1.91
2.64 2.14
Er ppm 1.81
2.83 0.29
0.28 0.32
0.31 0.30
0.40 0.41
0.41 0.31
Tm ppm 1.85
1.78 2.12
2.09 2.22
2.60 2.84
2.52 2.03
Yb ppm 0.33
0.34 0.33
0.39 0.27
0.29 Lu ppm
0.30 0.39
0.40 408
534 640
618 630
595 771
639 Ba ppm
628 39.5
42.0 51.1
79.7 46.7
51.7 Cl ppm
75.0 59.5
91.8 16.3
8.93 9.86
14.2 17.9
19.6 14.1
19.2 13.2
Co ppm 158
107 81.2
92.9 119
126 116
149 97.3
Cr ppm 6.62
5.40 4.45
4.56 4.50
Hf ppm 5.46
4.41 5.01
5.10 9.59
9.48 11.4
12.0 Nb ppm
9.3 13.8
15.0 9.03
10.5 32.2
39.8 59.6
62.8 58.2
77.2 38.1
Ni ppm 42.8
60.2 108
115 104
107 144
145 155
208 101
Rb ppm 16.2
10.4 11.6
15.2 18.2
19.4 17.9
20.4 13.4
Sc ppm 301
294 242
238 282
Sr ppm 240
141 181
96.0
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Table 2 Continued CF3mig
RH3lCr RH1
RH4hCr CF1
CF2 RH2mig
CF3 RH2
N = 6 N = 5
N = 6 N = 14
N = 7 N = 12
N = 4 N = 14
N = 4 0.67
0.66 0.84
0.77 0.83
0.82 0.93
1.03 0.68
Ta ppm 10.4
8.12 15.2
11.2 10.3
11.1 Th ppm
9.6 12.9
13.8 2.39
1.98 2.74
2.56 2.56
2.21 3.18
3.32 U ppm
2.29 87.5
112 144
146 143
160 107
V ppm 88.9
153 22.2
21.3 24.0
23.1 23.9
27.8 30.1
33.1 23.2
Y ppm 100
94.3 64.0
78.1 101
116 157
166 69.9
Zn ppm 267
218 178
181 181
227 Zr ppm
225 175
203 0.067
0.061 0.039
0.044 0.063
0.071 Ag ppm
0.088 0.096
0.059 0.58
1.43 0.92
0.60 2.11
1.38 As ppm
b
1.03 0.56
1.12 1.38
0.67 0.46
0.82 0.67
0.38 1.16
0.84 0.88
Au ppb
b
0.17 0.14
0.056 0.12
0.18 0.045
0.24 0.23
0.12 Bi ppm
11.3 16.6
33.2 53.2
27.0 Cu ppm
19.0 24.0
32.4 30.8
0.2 0.29
Pd ppb
b
0.48 0.25
0.85 0.82
1.02 0.28
0.25 0.042
0.041 0.032
0.037 0.083
0.027 0.059
Sb ppm 0.045
0.089 0.10
0.18 0.053
0.10 0.13
0.18 0.56
0.12 0.053
Se ppm 17.4
10.6 6.6
14.8 23.5
28.2 Te ppb
b
36.0 8.7
21.4
a
The RH2mig and BB4mig are the averages of migmatites, respectively. Group RH3 have been divided into low-Cr RH3lCr and high-Cr RHhCr populations. Values in parentheses include many determinations below the detection limit C
graf
0.05 and Pd 0.2 ppm and show either the detection limit value or averages calculated excluding values below detection limits.
b
One to two anomalous analyses have been excluded from some group averages.
Fig. 4. Harker-type Cr, K
2
O, MgO and CIA Nesbitt and Young, 1982 variation diagrams for Archaean, autochthonous and allochthonous sedimentary rocks in the study area. Ar1 and Ar2-Archaean, Jqzt – Jatuli-type quartzites, H1 – H2-autochthonous
high-Cr, H3-autochthonous low-Cr, H4- a low-Cr suspect group of Ho¨ytia¨inen area. WK1 – WK2 main field-allochthonous Western Kaleva. AC1 is the average of Archaean crust Table 1.
large mafic component indicated by high contents of HREE, MgO and Pd. The H2 group has many
compositional similarities with H1 but the H2 average shows higher levels of most elements e.g.
MgO and lower SiO
2
Fig. 4 and Table 1. Some H3 pelites show enrichment of felsic source com-
ponents manifested as low MgO contents Fig. 4. The K
2
O, Rb and Bi enrichment not shown favour a source dominated by a late-Archaean
granite Kutsu; see Fig. 3. The H4 is a heteroge- neous group that deviates to some extent from the
WK1 main group in having higher K
2
O and lower Cr Fig. 4.
The allochthonous Western Kaleva WK sedi- mentary rocks have been divided into WK psam-
mites and SiO
2
-poor pelitic rocks WK2. The WK1 psammites Table 1 form a geochemically
homogeneous group Fig. 4 and most of the variation can be explained by grain size variation.
The more pelitic nature of WK2 is seen in enrich- ment of elements e.g. Al
2
O
3
, MgO, FeO, K
2
O that characterize clay minerals Table 1 but the
WK2 also seems to be enriched in a mafic source as seen in higher Sc and Cr relative to Th. The
WK1 migmatites are mainly psammitic fragments floating in tonalitic often trondjhemitic veined
gneisses WK2 migmatites. Both groups of migmatites only show the systematic depletion of
Bi compared to non-migmatitic samples Table 1.
4
.
3
. Boundary zone and S6ecofennian sedimentary rocks
The sedimentary rocks in the boundary zone BZ; Fig. 2 have been divided into psammitic
BZ1 and pelitic BZ2 groups. The BZ1 rocks are heterogeneous in chemical composition show-
ing high variation, e.g. in HREE, CaO, K
2
O, Th and Nb and the average Table 1 should be only
considered as an areal average. The southern Svecofennian sedimentary rocks
in the Rantasalmi – Haukivuori area have been classified into three groups RH1 – RH3. The
non-migmatitic RH1
rocks are
quartz-rich greywackes and the well-preserved RH2 rocks are
more pelitic in character. Both RH1 and RH2 show rather similar patterns in Fig. 6 where the
strong effect of weathering is seen in negative peaks of Ba, Sr, CaO, MnO and P
2
O
5
, and high CIA values Table 2. The depletion of HREE, Sc,
V, TiO
2
and enrichment of K
2
O, Rb, Th and especially U is the main difference when com-
pared to the Western Kaleva source. A relative
Fig. 5. Plots of La vs. Yb and EuEu vs. Gd
N
Yb
N
for selected sedimentary rocks in this study. Gd
N
and Yb
N
are chondrite-normalized values and EuEu has been calculated using Eu = Sm
N
+ Gd
N
2. The Archaean average has been calculated from the average in the Table 1 and Jatuli-type mafics from the average N = 21 in Lahtinen unpublished data.
Ar – Ar2-Archaean groups, Jqtz – Jatuli-type quartzites, H1 – H2-autochthonous high-Cr, H3-autochthonous low-Cr, RH1 – RH2- southern Svecofennian, RH3-southern Svecofennian. CF1 – CF3-central Svecofennian.
Fig. 6. Major- and trace-element distributions in averages of southern Svecofennian sedimentary rock groups RH1 – RH3 Table 2 from the Rantasalmi – Haukivuori area normalized to the average of Western Kaleva psammites WK1 in Table 1. RH3lCr and
RH3hCr are averages of low- and high-Cr populations of RH3.
enrichment of Zn to Ni and Co is also a charac- teristic feature. The RH2 group shows the relative
enrichment of CaO, Ba, Nb, V and Sc and low CrSc ratio favouring a new additional mafic
component in the RH2. The lower CIA values Table 2, which are normally higher in more
pelitic rocks, indicate that this additional compo- nent was less weathered. Compared to the RH1
and RH2 rocks the RH3 samples show lower CIA and higher CaO and Na
2
O with strong variation in the amount of mafic component Fig. 6 and
Table 2. The RH1 – RH2 migmatites vary from gneisses
with quartz veins and small melt patches cut by pegmatites to veined gneisses with abundant gran-
ite leucosome. The main differences Table 2 can be interpreted to show a more pelitic precursor
for migmatites but the slightly lower REE and especially deep negative Eu anomaly in some sam-
ples ask for a loss of felsic component. The slight depletion in Ba, K
2
O and KRb can be related to a loss of a K-feldspar component and the enrich-
ment of ferromagnesian components to the in- creased amount of restite. So it seems that these
migmatites are mainly in situ migmatites that show a complex mixture of restite and a melt
fraction in variable proportion in outcrop scale.
The sedimentary rocks in the central Svecofen- nian have been divided to three groups CF1 –
CF3 where the CF1 includes high-SiO
2
and high ThSc ] 1 psammites, CF2 lower ThSc 5 1
psammites and CF3 silt-pelite rocks. The non- migmatitic CF1 samples show LREE enrichment
compared to the Western Kaleva psammites Fig.
5. The depletion of elements characteristic of mafic components and the relative enrichment of
LREE, Sr, Th, U and Zr point to a larger felsic component relative to the WK psammites. The
chemical composition of the CF2 group shows an enrichment of mafic components relative to CF1.
CF3 is a heterogeneous group characterized by migmatites and thus the average Table 2 in-
cludes also mica gneiss fragments in migmatites. Mineralogically the CF3 rocks differ from the
CF1 – CF2 in the ubiquitous occurrence of garnet. The more clay-rich nature of CF3 is seen in lower
SiO
2
and higher MgO and K
2
O Table 2. The CF3 migmatites form an inhomogeneous group
ranging from samples with HREE enrichment to samples with HREE depletion and Eu enrichment
at low total REE abundances compared with less migmatitic CF3 samples. This is interpreted as
different amounts of restite and leucosome in sampled outcrops.
5. Discussion
