ISSN 1028-334X, Doklady Earth Sciences, 2017, Vol. 477, Part 2, pp. 1441–1444. © Pleiades Publishing, Ltd., 2017. Original Russian Text © Yu.V. Erokhin, V.A. Koroteev, V.V. Khiller, E.V. Burlakov, K.S. Ivanov, D.A. Kleimenov, 2017, published in Doklady Akademii Nauk, 2017, Vol. 477, No. 5, pp. 582–585.
GEOCHEMISTRY
The Kargapole Meteorite: New Data on Mineralogy Yu. V. Erokhina,*, Academician V. A. Koroteeva, V. V. Khillera, E. V. Burlakovb, K. S. Ivanova, and D. A. Kleimenovb Received February 13, 2017
Abstract—New data on the mineral composition of Kargapole meteorite, which was found in Kurgan oblast in 1961, are presented. It has been established that the meteoritic material is represented by olivine (chrysolite), orthopyroxene (bronzite), clinopyroxene (diopside), plagioclase (oligoclase), chromite, Fe and Ni metal particles (kamacite, taenite, tetrataenite), sulfides (troilite, pentlandite), chlorapatite, and merrillite. For the first time, diopside, tetrataenite, pentlandite, chlorapatite, and merrillite were identified in the Kargapole meteorite. The chemical compositions of all minerals studied are given in Table 1. In terms of petrology, the meteorite is classified a common H4 chondrite. DOI: 10.1134/S1028334X17120121
The Kargapole meteorite was found in 1961 in Kurgan oblast by D.S. Okhapkin, a local of a settlement of the same name, 5 km to the southeast of the village of Osinovskoe and 12–13 km north of the Kargapole railway station [1, 2]. A piece of stone was in a grassy hole 10 cm deep. I.A. Yudin, a prominent researcher of meteorites studied the meteorite landing place in 1963 and brought two meteorite fragments (it was broken down into two fragments by D.S. Okhapkin) to the Uralian Commission on Meteorites (Sverdlovsk). It was later suggested that this piece of meteorite is a fragment of a large fireball that fell in autumn of 1942. The total weight of meteorite was 21.8 kg. Most of the meteorite was passed to the Vernadsky Institute of Geochemistry and Analytical Chemistry, Soviet Academy of Sciences (Moscow, Soviet Union), and a small fragment (9 kg 50 g) was left in the Ural Geological Museum (Sverdlovsk) [1, 2]. The latter piece was studied during our work. In terms of the structural features of the meteorite, it was proposed that it was detached from a large parent cosmic body. The meteorite is classified as a common chondrite of the H4 type [3]. The meteorite is of brown color due to weathering; there are local zones of melting and rhegmaglypts (solidified drops of melt). The mineral composition is as follows: olivine, orthopyroxene, chromite, kamacite, taenite, troilite, and magnetite; a Institute
of Geology and Geochemistry, Ural Branch, Russian Academy of Sciences, Yekaterinburg, 620016 Russia b Ural Geological Museum, Ural State Geological University, Yekaterinburg, 620144 Russia *e-mail:
[email protected]
secondary supergene minerals are goethite, iddingsite, bravoite, pyrite, and kaolinite [1–4]. Unfortunately, the diagnostics of minerals, as a whole, was performed on the basis of optical petrography. The K–Ar age of minerals varies in the range of 4.25 ± 0.15 Ga [3]. Recently, we reviewed the collection of meteorites of the Urals, stored in the Ural Geological Museum (Yekaterinburg). As a result, new data on the Kargapole chondrite were obtained that complement significantly the literature data available. Olivine is the main rock–forming mineral in the chondrite matrix, occurring as chondrules and grains of up to 0.8 mm in diameter. The mineral is characterized by a stable chemical composition (Table 1, an. 1–4) and classified as forsterite with 19–20% of fayalite minal. Orthopyroxene occurring both in chondrules (up to 3 mm in diameter) and the rock matrix (grains of up to 0.2–0.3 mm) is attributed to enstatite with 17– 18% of ferrosilite minal (Table 1, an. 5–8). Clinopyroxene, not determined previously, occurs more rarely; clinopyroxene grains of up to 30–40 μm in size are confined to segregations of enstatite. The mineral is characterized by a stable composition (Table 1, an. 9–10), all measurement points lie in the field of diopside (En47–48Wo46–47Fs6–7) at the boundary with the augite field in fact. Plagioclase occurs as small grains of up to 0.1 mm in size and fills the xenomorphic interstice space between grains of rock–forming minerals, in particular, in chondrules (Fig. 1). In terms of chemical composition, it refers to oligoclase (Table 1, an. 11–13) with anorthite (11–12%) and orthoclase (6–7%) minals. Cr spinel occurs as xenomorphic and isometric grains of up to 100 μm in size spreading through the
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Table 1. Chemical composition of silicates and oxides (wt %) from the Kargapole meteorite Ser. no
SiO2
TiO2
Al2O3
Cr2O3
NiO
FeO
MnO
MgO
CaO
Na2O
K2O
Total
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
38.98 39.00 39.24 39.26 56.05 56.57 56.08 55.96 53.52 54.07 65.18 65.59 64.99 – – –
0.01 0.01 – 0.01 0.20 0.05 0.19 0.14 0.58 0.54 0.06 0.04 0.02 2.19 2.26 2.29
– 0.01 – 0.01 0.19 0.04 0.19 0.13 0.58 0.61 21.30 21.10 21.39 6.49 6.43 6.43
0.10 0.08 0.03 – 0.12 0.07 0.16 0.18 0.88 0.82 – 0.01 – 58.06 58.79 58.33
– 0.07 – – 0.05 0.02 – 0.04 0.17 0.19 – 0.04 0.06 0.04 0.01 0.02
18.07 17.54 17.87 18.14 11.30 11.37 11.66 11.73 4.52 4.52 0.52 0.60 0.80 29.45 29.06 29.09
0.43 0.49 0.47 0.52 0.52 0.50 0.49 0.50 0.28 0.20 – – – 0.78 0.80 0.76
41.88 42.06 41.84 41.77 30.22 30.22 30.16 30.25 16.24 16.72 0.01 0.19 – 2.73 2.85 2.86
0.01 0.02 0.01 0.05 0.87 0.80 0.89 0.59 22.27 22.41 2.44 2.21 2.58 0.01 – 0.01
– – 0.01 – 0.01 0.03 0.02 – 0.56 0.59 9.92 9.64 10.22 0.01 – –
– – 0.01 0.01 – – – 0.01 – 0.01 1.17 1.31 0.68 0.01 – –
99.48 99.27 99.48 99.76 99.53 99.66 99.84 99.54 99.61 100.70 100.58 100.73 100.76 99.77 100.22 99.79
Here and further, analyses were performed using a CAMECA SX 100 microprobe analyzer at the Institute of Geology and Geochemistry, Ural Branch, Russian Academy of Sciences; an. 1–4, olivine; an. 5–8, orthopyroxene; an. 9–10, clinopyroxene; an. 11–13, plagioclase; an. 14–16, chromite.
entire matrix of the meteorite. As evidenced from the microprobe analysis, chromespinelide (Table 1, an. 14–16) is attributed to chromite with the following minals of hercynite (up to 14%), ulvospinel (up to 5%), and magnesiochromite (up to 15%). In the hardening zone of the chondrite and rims, spinel is altered intensively with an increasing iron content up to formation of Cr magnetite. Apatite, previously not identified, is dispersed throughout the chondrite matrix and occurs as rela-
Ol Tr
Chr Km Opx
Plg Km 100 µm
Tr
Fig. 1. Plagioclase–olivine chondrule with barred texture in the matrix of the Kargapole chondrite (BSE image, Cameca SX 100). Ol, olivine; Opx, orthopyroxene; Plg, plagioclase; Tr, troilite; Km, kamacite; Chr, chromite.
tively large elongated xenomorphic grains up to 300– 400 μm in size. Phosphates are replaced by goethite aggregate in the rims and along fractures. The mineral is characterized by a stable chemical composition (Table 2, an. 1–5) and is classified as chlorapatite. The crystallochemical conversion yields the following variations in the anion grouping: from (Cl0.63OH0.22F0.15) to (Cl0.76F0.18OH0.06). In terms of composition, phosphate is comparable with apatite from H-type chondrites [5, etc.]. Merrillite, previously not identified, occurs as relatively large xenomorphic grains of up to 500 μm and dispersed throughout the chondrite matrix, but without any connection with apatite. Phosphates are altered by a goethite aggregate in the rims and along fractures. This mineral is also characterized by a stable composition (Table 2, an. 6–10) and is identified with confidence as merrillite. Merrillite is a typomorphic mineral of common chondrites, which is nearly always characterized by stable composition independently of the type of meteorite [6–7, etc.]. It is interesting that the occurrence of merrillite in the chondrite is evidence of a low P content in the adjacent metal phases, and, correspondingly conversely, its absence assumes the occurrence of shreibersite or other iron phosphides in the rock [8]. The Fe and Ni metal phases in the Kargapole meteorite dispersed throughout the matrix of the chondrite are represented by kamacite, taenite, and tetrataenite. Kamacite occurs as the largest irregular grains up to 0.5 mm in diameter, and it is characterized by a low Ni content in the range of 6–13 wt % (Table 3,
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Table 2. Chemical compositions of phosphate minerals (wt %) from the Kargapole meteorite Ser. no
P2O5
SiO2
Cr2O3
FeO
1 2 3 4 5
41.49 41.67 41.55 41.43 40.93
0.34 0.23 0.43 0.54 0.24
0.06 0.11 0.10 0.11 0.01
1.16 0.75 1.07 0.59 0.88
6 7 8 9 10
46.70 46.63 46.53 46.97 47.03
0.23 0.08 0.03 0.07 0.06
0.03 0.05 0.05 0.01 0.01
0.87 1.07 1.01 0.93 0.96
MnO
MgO
Chlorapatite 0.03 0.02 0.02 0.05 0.01 0.02 0.11 0.02 0.04 0.02 Merrillite – 3.41 0.06 3.52 0.01 3.60 – 3.61 0.04 3.56
CaO
Na2O
Cl
F
Total
53.57 53.74 53.56 53.28 53.74
0.31 0.25 0.29 0.26 0.32
5.25 4.29 4.46 4.79 4.68
0.68 0.54 0.89 0.66 1.05
102.91 101.65 102.38 101.79 101.91
45.74 47.01 47.31 46.95 46.89
2.51 2.89 2.74 2.71 2.85
0.25 0.01 – 0.02 0.01
0.09 0.07 0.12 0.07 0.06
99.83 101.39 101.43 101.34 101.48
Table 3. Chemical composition of metals and sulfides (wt %) from the Kargapole meteorite Ser. no
Cr
Fe
Co
1 2 3
0.34 0.38 0.25
93.06 92.83 87.16
0.31 0.34 0.42
4 5 6
0.53 0.44 0.27
69.46 58.95 52.57
0.09 0.07 0.09
7 8 9
0.17 0.25 0.21
49.21 47.62 46.05
– – 0.02
10 11 12 13
0.02 0.02 0.01 0.80
63.22 63.30 55.85 57.12
– – 0.34 0.11
14 15
0.01 0.05
29.70 35.85
0.93 0.17
Ni Kamacite 5.79 6.01 12.83 Taenite 29.19 41.17 48.07 Tetrataenite 51.17 52.54 54.14 Troilite 0.08 0.04 8.20 8.95 Pentlandite 34.93 30.24
an. 1–3). Plessite was previously noted [3] in the core of large kamacite grains (an overgrowth of kamacite with taenite). Here, taenite occurs as single small rounded grains of up to 100 μm, and it is characterized by a higher Ni content in the range of 30–48 wt % (Table 3, an. 4–6). Tetrataenite was identified in this meteorite for the first time; it forms thin rims of up to 10 μm around taenite grains. In terms of composition, tetrataenite is more nickel–containing (Ni in the DOKLADY EARTH SCIENCES
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Mn
Cu
S
Total
– – 0.02
– – –
0.03 0.04 0.01
99.53 99.60 100.69
– 0.05 –
0.18 0.21 0.32
0.02 – 0.01
99.47 100.89 101.33
0.04 – –
0.36 0.19 0.21
0.02 – 0.02
100.97 100.60 100.65
0.06 0.04 0.02 –
– 0.04 0.04 0.05
36.35 35.78 35.29 34.05
99.73 99.22 99.75 101.08
0.01 0.06
0.53 0.15
32.72 33.30
98.84 99.83
range of 51–54 wt %, Table 3, an. 7–9). It is interesting that these rims were previously identified as bravoite [3] or pyrite [4]. In subsequent publications, no mention has been made of these minerals [1, 2]. Troilite occurs as single grains or forms aggregates of up to 0.5 mm in diameter, sometimes in intergrowths with kamacite, and highly dominates in its proportion over metals. Troilite is characterized by a stable chemical composition without any admixtures
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(Table 3, an. 10–13). Here, there is a sharp increase in the Ni content (up to 8–9 wt %) in the rims of grains up to the first occurrence of pentlandite rims proper (Table 3, an. 14–15). In terms of the chemical composition, troilite is attributed to Fe pentlandite and pentlandite proper (classified after [9]) and contains significant Co (up to 0.9 wt %) and Cu (up to 0.5 wt %) admixtures [10]. The entire matrix of the chondrite is “fractured” by a fine net of fractures filled with goethite, which is likely to inherit troilite veinlets by analogy with the Chelyabinsk [11] and Kunashak [12] meteorites. In addition, goethite fills wider late fractures and pseudomorphic aggregates over ore minerals and is characterized by a higher Ni content (NiO up to 3.5 wt %). In the classification diagram plotted for olivine and clinopyroxene from stone chondrites [13], the Kargapole meteorite lies in the H-type field. Taking into account the average Co content in kamacite (within the range of 0.3–0.4 wt %), this meteorite can be attributed to the H4-type (according to classification in [14]). Against the background of the groundmass of the meteorite, chondrules appear quite distinct. According to the classification of common chondrites [15], the petrological type of meteorite can be classified as H4. Thus, the chemical composition of the Kargapole meteorite (chondrite) has been studied and reported in this work for the first time. The following new minerals of the Kargapole meteorite have been identified: diopside, tetrataenite, pentlandite, chlorapatite, and merrillite. In terms of petrology, this meteorite has been classified as the H4 type. ACKNOWLEDGMENTS
REFERENCES 1. V. N. Loginov, Extended Abstract of Doctoral Dissertation in Geology and Mineralogy (Yekaterinburg, 1991). 2. V. N. Loginov, Meteorites of the Urals (Ural State Mining Univ., Yekaterinburg, 2004) [in Russian]. 3. L. N. Ovchinnikov and I. A. Yudin, Meteoritika, No. 27, 76–88 (1966). 4. I. A. Yudin, Meteoritika, No. 30, 158–168 (1970). 5. R. H. Jones and J. A. McCubbin, in Proc. 43rd Lunar Planet. Sci. Conf. (Woodlands, TX, 2012), Abstr. No. 2029. 6. R. P. Lozano and T. Martin-Crespo, Meteorit. Planet. Sci. 39 (8), 157–162 (2004). 7. A. M. Reyes-Salas, G. Sanchez-Rubio, P. AltuzarCoello, F. Ortega-Gutierrez, D. Flores-Gutierrez, K. Cervantes-de la Cruz, E. Reyes, and C. Linares, Rev. Mex. Cienc. Geol. 27 (1), 148–161 (2010). 8. A. Ruzicka, M. Killgore, D. W. Mittlefehldt, and M. D. Fries, Meteorit. Planet. Sci. 40 (2), 261–295 (2005). 9. N. N. Shishkin, A. M. Karpenkov, E. A. Kulagov, and G. A. Mitenkov, Dokl. Akad. Nauk SSSR 217 (1), 194–197 (1974). 10. Yu. V. Erokhin, S. V. Berzin, V. V. Khiller, and K. S. Ivanov, Litosfera, No. 3, 139–146 (2016). 11. V. A. Koroteev, S. V. Berzin, Yu. V. Erokhin, K. S. Ivanov, and V. V. Khiller, Dokl. Earth Sci. 451 (2), 839– 842 (2013). 12. Yu. V. Erokhin, V. A. Koroteev, V. V. Khiller, E. V. Burlakov, K. S. Ivanov, and D. A. Kleimenov, Dokl. Earth Sci. 464 (2), 1058–1061 (2015). 13. A. J. Bearley and R. H. Jones, in Planetary Materials (Min. Soc. America, Washington, DC, 1998), pp. 35– 38. 14. R. J. Reisener and J. I. Goldstein, Meteorit. Planet. Sci. 38 (11), 1679–1696 (2003). 15. W. R. Van Schmus and J. A. Wood, Geochim. Cosmochim. Acta 31 (5), 747–765 (1967).
This work was supported by the Russian Foundation for Basic Research, project no. 17–05–00297-а.
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Translated by Dm. Voroschuk
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