intrusion, Kola Peninsula; a second occurrence in Russia. ... P. Men'shikov & L. P. Barkova, Geological Institute, Kola Science Centre, Russian Academy.
Loveringite from the Last-Yavr mafic-ultramafic intrusion, Kola Peninsula; a second occurrence in Russia AND REW Yu. BA RKOV, YEVGENY E. SAVCHENKO, YURII P. MEN'SHIKOV & LARISSA P. BA RKOVA
& Barkova, L. P. : Loveringite from the Last-Yavr mafic-ultramafic
Barkov, A. Yu., Savchenko, Ye. E., Men'shikov, Yu, P.
intrusion, Kola Peninsula; a second occurrence in Russia. Norsk Geologisk Tidsskrift, Vol. 76, pp. 1 15 - 1 20. Oslo 1996. ISSN 0029- 196X. Loveringite,
(Ca, REE)(Ti, Fe, Cr),1038 ( a member of the crichtonite group) occurs in orthocumulates (plagioclase-bearing
orthopyroxenites) of the Last-Yavr intrusion, which obviously represents a fragment of the Proterozoic Fedorova Tundra-Pana Tundra layered intrusion. The occurrence is situated immediately adjacent to the Archaean wall rocks at a lower structural leve! of the intrusion. The loveringite is closely associated with a typical intercumulus assemblage (phlogopite, quartz, albite-rich plagioclase, ilmenite, rutile and Ca-amphibole). Its composition is characterized by a relatively low content of REE and high concentrations of Cr and Mg. The rellectance values are in good agreement with published data; VHN 100= 9 1 2- 1 085. The unit-cell dimensions are a= 10.40 (3), c= 20.83 (6)
Å.
A. Yu. Barkov•, Ye. E. Savchenko, Yu. P. Men'sh ikov & L. P. Barkova, Geological Institute, Kola Science Centre, Russian Academy of Sciences,
14
184200
Fersman Street,
Apatity, Russia. • Present address: Department of Geosciences and Astronomy, University of
Oulu, FTN-90570 Oulu, Finland.
Introduction
between the hetter known Fedorova Tundra and Pana
Loveringite, (Ca, REE)(Ti, Fe, Crb 038, a rare member of
the
crichtonite
group,
was
first
described
by
Gatehouse et al. ( 1978) from the Early Proterozoic Jim
Tundra intrusions (Fig. l ). The intrusions are located between Archaean granitoids and the Palaeoproterozoic Seidorechensky volcanogenic-sedimentary sequence. Fea-
berlana layered intrusion, Australia. The mineral has also been discovered in the Bushveld layered complex, South Africa (Cameron 197 8; 1979), and later in several Early Proterozoic mafic-ultramafic layered intrusions in Finland: Narankavaara, Penikat (Alapieti 1982; Alapieti
& Lahtinen 1986) and Koitelainen (Tarkian & Mutanen 1987). Another Fennoscandian occurrence of members of the loveringite-davidite series was reported by Olerud (1988) from an Early Proterozoic albite felsite, Norway. Segalstad ( 1984) described an unusual Ti-rich oxide min
cs;:]1 �2 r:::3:::;] �4 !S]s �6 �7
eral, the chemistry of which resembles that of the crich tonite group. Lorand et al. (1987) reported an occurrence of loveringite from the Early Palaeozoic Laouni complex, AJgeria. More recently, loveringite was identified in the Burakovsky layered intrusion, Russian Karelia (Barkov et al. 1994). Minerals of the loveringite-crichtonite series have also been found in the Khibina alkaline complex, Kola Peninsula, Russia (Barkov et al., in prep.). In this paper we report a second Russian occurrence of
loveringite,
from
the
Last-Yavr
intrusion,
t
N o 2 '--L....J KM
Kola
Peninsula.
Fig.
l. Simplified geological sketch-map of the contact area between the Fe
dorova Tundra and Pana Tundra layered intrusions, showing location of the Last-Yavr intrusive body. Modified from Radchenko et al. ( 1980)
l. Geological
contacts; 2. Schists and mylonites after mafic and ultramafic rocks; 3. Archaean
Brief geological description The Last-Yavr mafic-ultramafic intrusion is situated in the central part of the Kola Peninsula, at the contact
granitoids;
4. Palaeoproterozoic Seidorechensky complex of volcanic and sedi
mentary rocks; 5. Faults; 6. Position of drill hole No. 72; 7. Mafic-ultramafic igneous rocks. Abbreviations used: Ff= Fedorova Tundra,
PT= Pana Tundra,
LY = Last-Yavr intrusions. The inset shows the approximate location of the area on the Kola Peninsula.
116 Table
A. Yu. Barkov et al.
NORSK GEOLOGISK TIDSSKRIFT 76 (1996)
I. Representative electron microprobe analyses (in wt.%) of minerals in loveringite-bearing pyroxenite from Last-Yavr. En
Aug
Si02
55. 1 7
52.99
Ti02
0. 1 5
Al203
Pl
Phi
Am
Ap
Chr
co re
rim
59.06
60.30
40. 4 1
48. 1 0
n.a.
n.a.
n.d.
0.62
n.d.
n.d.
2.63
0.40
n.a.
n.a.
0.30
1.17
2.27
25.57
25.85
14.55
1 1 .38
n.a.
n.a.
9. 82
Cr203
0.33
0.64
n.d.
n.d.
0.7 1
0. 1 0
n.a.
n.a.
43. 1 8
V20,
n.d.
0.04
n.d.
n.d.
0.05
n.d.
n.a.
n.a.
0.74 1 1 .75
Fe203 FeO
10. 8 1
6. 1 8
0. 12
0. 10
5.89
7.7 1
0. 1 9
0.24
MnO
0.27
0. 1 7
n.d.
n.d.
0.04
0. 1 3
n.a.
n.a.
MgO
30.70
1 8.65
n.d.
n.d.
22.65
17.05
n.a.
n.a.
CaO
1.14
1 7.32
7.10
7. 1 3
0.04
10.79
54.64
54.39
n.d.
SrO
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
0. 1 1
n.d.
n.a.
Na20
0. 1 6
0.46
7.21
8.07
0.47
2. 1 0
n.a.
n.a.
n.a.
K20
n.d.
n.d.
0.03
O.o3
8.6 1
0. 1 0
n.a.
n.a.
n.a.
29.61 0.45 1.32
Ce203
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
0.2 1
0. 1 2
n.a.
NiO
0.09
0.05
n.a.
n.a.
0. 1 3
0.06
n.a.
n.a.
n.d.
ZnO
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
P20s
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
42.08
42.30
n.a.
n.a.
n.a.
n.a.
n.a.
n.d.
0.06
1 .45
1.56
n.a.
0.0 1
0.33
0.36
97.97
98.35
98.25
Cl
Cl-O 99.99
Total
99.39
1 0 1.48
99.09
96. 1 8
0.84
98.0 1
Number of cations 0= 1 1
0= 8 Si
1.94
1.94
Ti
