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Redistribution of Sr and rare earth elements in the matrices of CV3 carbonaceous chondrites during aqueous alteration in their parent body

Redistribution of Sr and rare earth elements in the matrices of CV3 carbonaceous chondrites... We measured the abundances of Sr and rare earth elements (REEs) in the matrices of five CV3 carbonaceous chon- drites: Meteorite Hills (MET ) 00430, MET 01070, La Paz ice field (LAP) 02206, Asuka (A) 881317 and Roberts Massif (RBT ) 04143. In the MET 00430 and MET 01074 matrices, the Sr/CI and light REE (LREE, La–Nd)/CI ratios positively correlate with the amounts of Ca-rich secondary minerals, which formed during aqueous alteration in the CV3 chondrite parent body. In contrast, in the LAP 02206 and RBT 04143 matrices, although the Sr/CI ratios correlate with the amounts of Ca-rich secondary minerals, the LREE/CI ratios vary independently from the amounts of any secondary minerals. This suggests that the LREE/CI ratios in these matrices were produced prior to the parent body alteration, probably in the solar nebula. The LREE/CI ratios of the LAP 02206 and RBT 04143 matrices reveal the mixing process of matrix miner- als prior to the accretion of the CV3 chondrite parent body. The mixing degrees of matrix minerals might be different between these two matrices. Because solid materials would be mixed over time according to the radial diffusion model of a turbulent disk, the matrix minerals consisting of LAP 02206 and RBT 04143 matrices might be incorporated into their parent body with different timing. Keywords: Rare earth element, CV3 carbonaceous chondrite, Aqueous alteration, Solar nebula Introduction ordinary chondrites (e.g., Alexander 1995; Bland et  al. In water-bearing asteroids, aqueous alteration, the chem- 2005). In contrast, in primitive carbonaceous chondrites ical reaction between aqueous fluids and primary min - (e.g., CO3 and CV3), only CV3 Bali, which has similar erals formed in the solar nebula, had taken place after alteration conditions to CM2 or CR2 chondrites, shows the melting of ice due to the decay heat of short-lived higher Sr abundances of matrix compared to CI chon- 26 60 radiogenic nuclides such as Al and Fe (e.g., Brearley drite (e.g., Bland et  al. 2005). Typically, matrices in CO3 and Krot 2013). During the aqueous alteration, soluble and CV3 chondrites preserve the Sr abundance of CI elements (e.g., Sr) would be redistributed from primary chondrite (e.g., Hua et al. 1996; Bland et al. 2005; Martin minerals in the matrices, chondrules and Ca–Al-rich et  al. 2013). This indicates that elements with relatively inclusions to secondary minerals through aqueous flu - lower solubility compared with Sr (e.g., Au, Ga and Se) ids. This process would result in non-CI–chondritic Sr would not be redistributed during aqueous alteration abundances of matrices in the heavily aqueous-altered (e.g., Bland et al. 2005). carbonaceous (e.g., CM2 and CR2) and unequilibrated However, it was found that Sr is present in second- ary minerals in matrices of CV3 Allende and Vigarano chondrites (Dyl et  al. 2014). In addition, Sr abundances *Correspondence: kaorijogo@kopri.re.kr of some parts of Allende matrix are different from CI Division of Earth-System Sciences, Korea Polar Research Institute, 26 chondrite abundance (Inoue et al. 2004). Because Allende Songdomirae-ro, Yeonsu-gu, Incheon 21990, South Korea and Vigarano are typical CV3 chondrites and are not Full list of author information is available at the end of the article © The Author(s) 2018. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Jogo et al. Earth, Planets and Space (2018) 70:37 Page 2 of 9 heavily aqueous-altered as is Bali, we expect that redis- magnetite and altered silicates occur in these matrices tribution of Sr might have occurred even in the typical (Fig. 1a, b and Additional file  1: Table S1). These mineral CV3 chondrites during aqueous alteration in their parent species are similar to those of C V3 matrices (e.g., Krot OxB body. To verify this hypothesis, we measured the Sr and et al. 1998). In the LAP 02206 host matrix, Ca-pyroxene, REE (lower solubility than Sr) abundances of matrices in awaruite, Fe, Ni-sulfide, ferrous olivine, sodalite and the CV3 MET 00430, MET 01070, LAP 02206, A 881317 plagioclase were observed (Fig.  1c and Additional file  1: and RBT 04143 chondrites using secondary ion mass Table S1). These mineral species are consistent with spectrometry. those of CV3 matrices (e.g., Krot et  al. 1998). In the OxA A 881317 matrix 5, Ca-pyroxene, Ca-phosphate, relict Fe, Results Ni-metal, ferrous olivine and magnetite were observed Mineralogy of CV3 chondrites (Fig. 1d and Additional file  1: Table S1). Fe-sulfide and Fe, We performed mineralogical observations of five CV3 Ni-sulfide are rare. These mineralogical features are simi - chondrites including all CV3 subtypes: the oxidized lar to those of the C V3 matrix (e.g., Krot et  al. 1998), Ox Allende-like type (CV3 ) LAP 02206, the oxidized Bali- suggesting that the clast including the A 881317 matrix OxA like type (CV3 ) MET 01074 and CV3 MET 00430, 5 would be the CV3 clast in the CV3 A881317 brec- OxB OxB Ox Red and the reduced type (C V3 ) RBT 04143 and C V3 A cia. In the RBT 04143 matrices 5 and 6, similar primary Red Red 881317 (e.g., Weisberg et  al. 1997). The analytical meth - and secondary minerals were observed: kirschsteinite, ods are described in Additional file  1. These samples are Ca-pyroxene, Ca-phosphate, Fe, Ni-metal, kamacite, all Antarctic find-type meteorites, and their terrestrial Fe-sulfide, Fe, Ni-sulfide, ferrous olivine and magnetite weathering grades are A/B for RBT 04143, B for MET occur in these matrices (Fig.  1e, f and Additional file  1: 00430, MET 01047 and LAP 02206, and no data for A Table S1). Small Fe, Ni-sulfide grains (< 2 µm in size) are 881317 (e.g., Meteorite bulletin). A section of RBT 04143 abundant only in the RBT 04143 matrix 6 (Fig.  1f and that we studied contains Fe oxide weathering products Additional file  1: Table S1). These mineralogical fea - in cracks and fractures of the section (Additional file  1: tures are similar to those of the C V3 matrix (e.g., Krot Red Fig. S1). In contrast, sections of the other four CV3 chon- et al. 1998). We could not find any evidence of terrestrial drites do not contain such weathering products. weathering such as oxidation of opaques in the measured The general petrography of these five CV3 chondrites matrices (e.g., Wlotzka 1993). was described in Ishida et  al. (2015) and Jogo et  al. (2017). Briefly, the RBT 04143 and A 881317 chondrites Chemical compositions of the matrices are breccias consisting of many clasts (e.g., Fig. 2 in Jogo We measured the chemical compositions of six matrices et  al. 2017). A typical clast (from 0.5 to 1  mm in size) is (analytical methods are described in Additional file  1): 14 composed of chondrules and surrounding olivine-rich data from the CV3 MET 00430 host matrix, 10 data OxB fine-grained materials. The clasts are either embedded in from the CV3 MET 01070 host matrix, 11 data from OxB the host matrix or in direct contact with adjacent clasts. the CV3 LAP 02206 host matrix, 5 data from the OxA In contrast, such clasts were not observed in the LAP CV3 A 881317 matrix 5, 5 data from the CV3 RBT Ox Red 02206, MET 00430 or MET 01074 chondrites. 04143 matrix 5 and 3 data from the C V3 RBT 04143 Red For a more detailed mineralogical and chemical anal- matrix 6. We carefully chose matrix areas without Fe ysis, we selected six matrices: host matrices from the oxide weathering veins in CV3 RBT 04143 (Additional Red MET 00430, MET 01074 and LAP 02206 chondrites, one file 1: Fig. S1). matrix from the A 881317 chondrite (A 881317 matrix 5) The measured matrices have various Sr abundances and two matrices from the RBT 04143 chondrite (RBT and show some departures from CI chondrite abundance 04143 matrix 5 and matrix 6) (Fig.  1). In the RBT 04143 (Fig.  2 and Additional file  1: Table S2). The averaged Sr/ and A 881317 breccias, we chose the matrices with clear Yb ratios normalized to the CI chondrite abundance of clast boundaries in the backscattered electron images each matrix are < 0.8 or > 1.3 (Additional file  1: Table (Fig. 1). S2). The averaged Sr/CI ratios are 0.9–3.2, and only the All of the matrices we measured consist primarily of CV3 LAP 02206 host matrix and the CV3 RBT OxA Red ferrous olivine grains, but the grain sizes and porosities 04143 matrix 5 show CI chondrite abundance (averaged differ among matrices (e.g., Fig.  1). Primary and second- Sr/CI ratios of 0.9–1.0). The range of Sr/CI ratios within ary minerals occur between matrix olivine grains. Their an individual matrix is different among matrices. The species and distributions are different in each matrix. CV3 LAP 02206 host matrix, the CV3 A 881317 OxA Ox In the host matrices of MET 00430 and MET 01074 matrix 5 and the C V3 RBT 04143 matrix 5 show Red chondrites, similar secondary minerals were observed; moderately broad Sr/CI ratios with a standard devia- Ca-pyroxene, Fe, Ni-sulfide, ferrous olivine, fayalite, tion of < 0.4. The rest of the CV3 MET 00430 and the OxB Jogo et al. Earth, Planets and Space (2018) 70:37 Page 3 of 9 CV3 MET 01074 host matrices and the C V3 RBT clear correlation between La/CI ratios and modal abun- OxB Red 04143 matrix 6 show broad Sr/CI ratios with a standard dances of magnetite in these matrices (Table 1 and Addi- deviation of > 0.8. tional file 1: Fig. S3). The LREE abundances of measured matrices are also various and show some departures from CI chondrite Discussion abundance (Fig.  2 and Additional file  1: Table S2). The The effect of terrestrial weathering on matrix Sr and LREE averaged LREE/CI ratios of the CV3 A 881317 matrix abundances Ox 5 and the C V3 RBT 04143 matrices 5 and 6 are similar The weathering grades of our samples are A/B to B, Red to CI chondrite abundance (e.g., averaged La/CI ratios of whereas no Fe oxide weathering products were observed 1.0–1.4). The rest of the CV3 MET 00430 and CV3 in their matrices (e.g., Fig. 1); minor Fe oxide weathering OxB OxB MET 01074 host matrices and the CV3 LAP 02206 veins occur only in C V3 RBT 04143 (Additional file  1: OxA Red host matrix show higher LREE/CI ratios than CI chon- Fig. S1). In weathered Antarctic meteorites, the precipi- drite abundance (e.g., averaged La/CI ratios of 1.6–1.8). tation of Fe oxide weathering products is confined to The ranges of LREE/CI ratios are narrow in the CV3 fractures through the meteorite and voids in the fusion OxA LAP 02206 host matrix, the C V3 A 881317 matrix 5 crust, rather than being pervasively distributed through- Ox and CV3 RBT 04143 matrix 5 (e.g., standard deviation out the matrix (Abreu and Brearley 2010). The low per - Red of La/CI ratios of ~ 0.2–0.3), but they are broad in the meability of the matrix might limit the incorporation CV3 MET 00430 and CV3 MET 01074 host matri- of terrestrial water into the matrices and prevent them OxB OxB ces and the C V3 RBT 04143 matrix 6 (e.g., standard from experiencing terrestrial weathering. A similar pro- Red deviation of La/CI ratios of ~ 0.5–0.7). Small Ce anoma- cess might have occurred in the matrices we measured lies are detected in each matrix (Fig.  2). The Ce anoma - and result in no precipitation of weathering products in lies are not correlated with the matrix compositions with them because CV3 matrices would have low permeabil- respect to soluble elements such as Ca, Sr and Nd (Addi- ity (Bland et al. 2009). Based on the weathering scale for tional file 1: Fig. S2). ordinary chondrites (e.g., Wlotzka 1993), the weathering The abundances of middle to heavy REEs (MREE and grades of the sections we studied are estimated to be W1 HREE; Nd–Lu) are less various compared to those of for CV3 RBT 04143 with minor Fe oxide weathering Red LREEs (Fig.  2). The MREE/CI and HREE/CI ratios are veins and W0 for the rest of the samples with no Fe oxide consistent with the errors within individual matrices weathering products. and among different matrices (MREE/CI = 0.2–3.6 and The measured matrices with weathering grade W1 HREE/CI = 0.5–2.4 in all matrices; Fig.  2 and Additional show similar or lower Ca, Sr and REE abundances com- file  1: Table S2). Most of the matrices show Eu anoma- pared to those with weathering grade W0 or matrices in lies with large uncertainties; both positive and negative the unweathered fall-type CV3 chondrites (Fig.  2g, Hua anomalies were detected in each matrix (Fig. 2). et  al. 1996; Inoue et  al. 2004; Bland et  al. 2005; Martin et  al. 2013). This may suggest that leaching of soluble Correlations between Sr/CI and La/CI ratios and chemical elements might occur during terrestrial weathering in composition of the matrix the matrices with weathering grade W1. However, they Correlations between the Sr/CI and La/CI (representa- do not show preferential depletion in soluble Ca, Sr and tive of REEs) ratios and chemical compositions of matrix LREEs compared to the find-type CV3 matrices. The have been investigated (Table  1, Fig.  3 and Additional depleted elements are Ce, Pr, Sm, Tb, Ho and Tm, which file  1: Fig. S3). For the Sr/CI ratio and Ca contents, all do not have high solubility in water, suggesting that sol- matrices except the CV3 RBT 04143 matrix 6 show uble element abundances of the matrices with weather- Red strong positive correlations with correlation coefficients ing grade W1 would not be disturbed during terrestrial of R ≧ 0.7. For the La/CI ratio and Ca contents, only host weathering. 3+ matrices in the CV3 MET 00430 and CV3 MET In addition, in Antarctic achondrites, oxidation of Ce OxB OxB 4+ 01074 chondrites show moderate to strong positive cor- to the more insoluble Ce caused the separation of this relations with correlation coefficients of R ≧ 0.6. For the element from the other LREEs, resulting in Ce anoma- La/CI ratio and the other elements’ contents, only the lies (e.g., Floss and Crozaz 1991; Crozaz et al. 2003). The CV3 A 881317 matrix 5 shows a moderate positive cor- leaching of soluble elements from achondrites would Ox relation between La/CI and P contents with a correlation cause low soluble element abundances with positive Ce coefficient of R ~ 0.6. The rest of the CV3 RBT 04143 anomalies. We expect that a similar process would occur Red matrices 5 and 6 and the C V3 LAP 02206 host matrix in the CV3 matrices we measured. However, a tendency OxA do not show strong positive correlations between La/CI for positive Ce anomalies to occur at low Ca, Sr and LREE and chemical compositions (R ≦ 0.3). There is also no concentrations was not found in the measured matrices Jogo et al. Earth, Planets and Space (2018) 70:37 Page 4 of 9 Fig. 1 Backscattered electron images of CV3 matrices: a CV3 MET 00430 host matrix; b CV3 MET 01074 host matrix; c CV3 LAP 02206 host OxB OxB OxA matrix; d CV3 A 881317 matrix 5; e CV3 RBT 04143 matrix 5; f CV3 RBT 04143 matrix 6. Clast boundaries between CV3 RBT 04143 matrices Ox Red Red Red 5 and 6 are shown by dotted lines in e and f. The weathering grade (A/B or B and W0 or W1) and matrix type (type 1 or 2) are also shown. All images are presented at the same magnification. awr awaruite, Ca -phs Ca-phosphate, Ca-px Ca-pyroxene, Fe-ol ferrous olivine, slf sulfide, kir kirschsteinite, mgt magnetite, ol olivine, pent pentlandite, pl plagioclase (Additional file  1: Fig. S2). This indicates the same con - preterrestrial processes, i.e., nebular or asteroidal altera- clusion that Ca, Sr and LREEs would not be leached from tion processes. Although only the CV3 RBT 04143 Red the matrices with weathering grade W1 during terrestrial matrix 6 shows a negative correlation between Sr abun- weathering. Therefore, the Ca, Sr and LREE abundances dances and Ce anomalies, it will not be discussed further of the matrices we measured would probably reflect because of its small number of data. Jogo et al. Earth, Planets and Space (2018) 70:37 Page 5 of 9 Fig. 2 CI-normalized REE, Sr and Ca abundances of CV3 matrices (a–f). Representative error bars (1σ) are shown in each matrix. Average composi- tions of find-type CV3 matrices [weathering grades of B and W0 (red), A/B and W1 (blue) and W0 (black)] and fall-type CV3 matrices (green) are shown in (g) Redistribution of Sr and LREEs in the matrix classified into two types (Table  1): [type 1] CV3 MET OxB during aqueous alteration in the parent body 00430 and CV3 MET 01074 host matrices, char- OxB Based on the correlation between the Sr/CI, La/CI ratio acterized by moderate to strong positive correlations and the Ca contents of a matrix, the matrices could be between the Sr/CI and La/CI ratios and the Ca contents Jogo et al. Earth, Planets and Space (2018) 70:37 Page 6 of 9 (R ~ 0.6–0.9); and [type 2] C V3 LAP 02206 host OxA matrix, CV3 A 881317 matrix 5 and C V3 RBT 04143 Ox Red matrix 5, characterized by strong positive correlation between the Sr/CI ratio and Ca contents (R ~ 0.7–0.9) but no strong correlation between the La/CI ratio and Ca contents (R ~ 0.0–0.2). We will discuss whether any redistribution of Sr and LREEs occurred during aque- ous alteration in type 1 and 2 matrices in the following sections. Type 1 matrix (CV3 MET 00430 and CV3 MET OxB OxB 01074 host matrices) The Sr/CI and La/CI ratios of a type 1 matrix are positively correlated with the Ca con- tents of the matrix (Table 1 and Fig. 3). This implies that the amounts or mineral species of the Ca-rich phase con- trol the Sr/CI and La/CI ratios of a type 1 matrix. The Ca- rich phase in a type 1 matrix is Ca-pyroxene (Additional file  1: Table S1 and Fig. 1a, b), which is a secondary min- eral formed during aqueous alteration in the CV3 chon- drite parent body (e.g., MacPherson and Krot 2014). The Sr and LREE partition coefficients in Ca-pyroxene from melt are highest among those in secondary minerals in a type 1 matrix (e.g., Kuehner et  al. 1989; Nielsen et  al. 1992; Kennedy et  al. 1993; Prowatke and Klemme 2006; Sun et  al. 2017, Additional file  1: Fig. S4). This suggests that the Sr and LREEs in aqueous fluids would be prefer - entially incorporated into Ca-pyroxene during its forma- Fig. 3 Ca (wt%) versus Sr/CI (blue) and Ca/CI (red) plots of CV3 matri- tion. Since the amounts of Ca-pyroxene minerals control ces. Error bars are 1σ. R : correlation coefficient the Sr and LREE abundances of the matrix, the Sr and LREE abundances of a type 1 matrix would be disturbed during aqueous alteration in the parent body. abundance of a type 2 matrix would be disturbed during Type 2 matrix (CV3 LAP 02206 host matrix, CV3 A aqueous alteration in the parent body. OxA Ox 881317 matrix 5 and CV3 RBT 04143 matrix 5) The Regarding the lack of a strong positive correlation Red Sr/CI ratios of the type 2 matrix are positively correlated between the La/CI ratio and Ca contents of the matrix, with the Ca contents of the matrix, but the La/CI ratios there could be two possible explanations: (1) La in the are not (Table 1 and Fig. 3). This implies that the amounts aqueous fluids was incorporated into Ca-poor second - or mineral species of the Ca-rich phase control the Sr/CI ary minerals, and the amounts of such minerals con- ratios of the matrix, but the La/CI ratios of the matrix are trolled the LREE abundances of matrix or (2) La was not controlled by other factors. dissolved in the aqueous fluids. There are no secondary minerals that have higher LREE partition coefficients Concerning positive correlations between the Sr/ than those of the Ca-rich secondary minerals in a type CI ratios and Ca contents, we adopt the same logic for 2 matrix (Additional file  1: Table S1 and Fig. S4). Thus, explaining the Sr abundance of type 1 matrix. The Ca- case 1 would not be possible. Therefore, we propose rich phases in type 2 matrix are kirschsteinite, Ca- case 2 as a mechanism for explaining the La/CI ratios of pyroxene, Ca-phosphate and plagioclase (Fig.  1c–e and the type 2 matrix. The lack of any clear positive correla - Additional file  1: Table S1), which are all secondary min- tions between La/CI ratios and chemical compositions erals (e.g., Krot et al. 1998; MacPherson and Krot 2014). of type 2 matrix would also support case 2 (Table  1 and Because the Sr partition coefficients in these minerals are Additional file  1: Fig. S3). Although the CV3 A 881317 Ox high (Additional file  1: Fig. S4), the Sr in aqueous fluids matrix 5 shows moderate positive correlation between would be preferentially incorporated into them during La/CI ratios and P contents (R ~ 0.6), the range of P con- their formation. Since the amounts of these secondary tent is too narrow to discuss the correlation (e.g., Addi- minerals control the Sr abundance of the matrix, the Sr tional file 1: Fig. S3-2a). Jogo et al. Earth, Planets and Space (2018) 70:37 Page 7 of 9 Table 1 Correlation coefficient (R ) of Sr/CI and La/CI ratios and chemical compositions of CV3 matrices N: number of data Negative correlation The correlations between Sr/CI, La/CI and the chemi - (e.g., Floss and Crozaz 1991; Bland et al. 2005). The LREE cal composition of type 1 and 2 matrices suggest that the abundances of type 2 matrix (the C V3 LAP 02206 OxA Sr abundances were disturbed in both type 1 and 2 matri- host matrix and the CV3 RBT 04143 matrix 5) would Red ces (including all C V3, CV3 and C V3 subtypes), not be disturbed during terrestrial weathering or aque- OxA OxB Red but those of LREEs were disturbed only in the type 1 ous alteration in their parent body (“The effect of ter - matrix (the C V3 subtype). There are also some CV3 restrial weathering on matrix Sr and LREE abundances” OxB chondrites (including all C V3, CV3 and CV3 and “Redistribution of Sr and LREEs in the matrix dur- OxA OxB Red subtypes) with Sr and REE abundances of matrices ing aqueous alteration in the parent body” sections). This that would not be disturbed during aqueous alteration then implies that their LREE abundances would reflect (e.g., Bland et  al. 2005). These findings may suggest that the nebular process prior to the accretion of their parent there is no correlation between CV3 subtypes (C V3 , body. OxA CV3 and CV3 ) and that there is some redistribu- In the CV3 LAP 02206 host matrix, the LREE pat- OxB Red OxA tion of Sr and/or LREE abundances in CV3 matrices. terns are similar among measurement spots: All are Because the dissolution of Sr and La in aqueous fluids convex downward with lower abundances of Ce and Pr would reflect the aqueous alteration conditions (e.g., than La and Nd (Fig.  2c). This may imply that (1) all the temperature, pH and chemical composition of fluids, matrix minerals experienced similar thermal processes Michard 1989), the lack of a correlation between sub- in the solar nebula or (2) although each matrix mineral types and Sr and La dissolution may imply that aqueous was formed by different nebular processes, they were alteration conditions might be various even in the same well mixed prior to the accretion to their parent body. subtype of CV3 chondrites. In contrast, in the C V3 RBT 04143 matrix 5, the Red LREE patterns are slightly different among measurement Implications for the CV3 chondrite parent body accretion spots (Fig.  2e). This may imply that the matrix minerals process retained their heterogeneity when the C V3 RBT 04143 Red The chemical compositions of CV3 matrices could reflect matrix accreted to its parent body. nebular processes, aqueous alteration in the CV3 chon- The specific minerals or nebular processes that con - drite parent body and/or terrestrial weathering processes trol the LREE abundances of matrices could not be Jogo et al. Earth, Planets and Space (2018) 70:37 Page 8 of 9 Author details constrained in this study. Inoue et  al. (2004) suggested Division of Earth-System Sciences, Korea Polar Research Institute, 26 the existence of some unknown LREE-enriched compo- Songdomirae-ro, Yeonsu-gu, Incheon 21990, South Korea. Kochi Institute nents in CV3 Allende matrices. The LREE abundances for Core Sample Research, JAMSTEC, B200 Monobe, Nankoku, Kochi 783-8502, Japan. Division of Earth and Planetary Materials Science, Tohoku University, of matrices might reflect the complementary chondrule/ Sendai, Miyagi 980-8578, Japan. Unit of Antarctic K-route Expedition, Korea matrix formation process in which the chondrules and Polar Research Institute, 26 Songdomirae-ro, Yeonsu-gu, Incheon 21990, South matrix formed complementarily from a single LREE res- Korea. ervoir (e.g., Inoue et al. 2004; Bland et al. 2005). Acknowledgements The different LEE patterns of the CV3 LAP 02206 OxA The meteoritic samples were provided by the National Institute of Polar and the C V3 RBT 04143 matrices may be explained by Research (Japan) and the NASA Johnson Space center. We thank Ms. Moon Red and Dr. Park for the support to use SEM and FE-EPMA. We appreciate the the radial diffusion model of a turbulent disk (Cuzzi et al. detailed comments from Dr. Fujiya and an anonymous reviewer. We also thank 2010). This could introduce the difference in the degree of Prof. Noguchi for the editorial handling. material mixing with time in the solar nebula. In the case Competing interests of (1), the CV3 LAP 02206 matrix would accrete to its OxA The authors declare that they have no competing interests. parent body before mixing with other matrix minerals. In the case of (2), matrix minerals were well mixed when Availability of data and materials The data and materials are available upon request from the corresponding the CV3 LAP 02206 host matrix accreted to its parent OxA author (kaorijogo@kopri.re.kr). body. In contrast, the matrix minerals retained their het- erogeneity when the C V3 RBT 04143 matrix accreted. Consent for publication Red Not applicable. To produce the difference in mixing degrees of matrix minerals, the matrix minerals consisting of CV3  LAP OxA Ethics approval and consent to participate 02206 and C V3   RBT 04143 matrices might be incor- Not applicable. Red porated into their parent body with different timing. Funding This work was supported by KOPRI project PM17030. MI was supported by the Summary JSPS Grants-in-Aid for Science Research (no. 26287142) from the Shimadzu Science Foundation (2016). This work was supported in part by the Kochi Core The Sr and REE abundances of six matrices in five CV3 Center Open Facility System under the MEXT foundation. chondrites were measured. The correlations between the Sr, La and Ca abundances of the matrices suggest that Sr Publisher’s Note and LREEs would have been redistributed in the MET Springer Nature remains neutral with regard to jurisdictional claims in pub- 00430 and MET 01070 matrices during aqueous altera- lished maps and institutional affiliations. tion in their parent body. Only the LAP 02206 and RBT Received: 21 December 2017 Accepted: 26 February 2018 04143 matrices would preserve the LREE abundances that reflect nebular processes. The correlations between the Sr, LREE and Ca abundances of matrices will be use- ful for distinguishing CV3 matrices with Sr and LREE abundances that reflect nebular processes from those References Abreu N, Brearley AJ (2010) Early solar system processes recorded in the matri- that reflect aqueous alteration processes in their parent ces of two highly pristine CR3 carbonaceous chondrites, MET 00426 and body. QUE 99177. Geochim Cosmochim Acta 74:1146–1171 Alexander CMOD (1995) Trace element contents of chondrule rims and Additional file interchondrule matrix in ordinary chondrites. Geochim Cosmochim Acta 59:3247–3266 Bland PA, Alard O, Benedix GK, Kearsley AT, Menzies ON, Watt LE, Rogers NW Additional file 1. The analytical methods and figures and tables showing (2005) Volatile fractionation in the early solar system and chondrule mineralogy and chemical compositions of CV3 matrices and the Sr and matrix complementarity. Proc Natl Acad Sci 39:13755–13760 REEs partition coefficients for mineral/melt. Bland PA, Jackson MD, Coker RF, Cohen BA, Webber JBW, Lee MR, Duffy CM, Chater RJ, Ardakani MG, McPhail DS, McComb DW, Benedix GK (2009) Why aqueous alteration in asteroids was isochemical: high poros- Abbreviations ity ≠ high permeability. Earth Planet Sci Lett 287:559–568 LREE, MREE and HREE: light, middle and heavy rare earth element; LAP: La Paz Brearley AJ, Krot AN (2013) Metasomatism in the early solar system: the record ice field; MET: Meteorite Hills; RBT: Roberts Massif; A: Asuka; CV3, CV3 and from chondritic meteorites. In: Harlov DE, Austrheim H (eds) Metasoma- OxA OxB CV3 : the oxidized Allende- and Bali-like and the reduced subtypes. tism and the chemical transformation of rock. 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Geochim Cosmochim Acta 70:4513–4527 drites: constraints on the accretion ages of chondritic asteroids. Geochim Sun C, Graff M, Liang Y (2017) Trace element partitioning between plagioclase Cosmochim Acta 199:58–74 and silicate melt: the importance of temperature and plagioclase com- Kennedy AK, Lofgren GE, Wasserburg GJ (1993) An experimental study of position, with implications for terrestrial and lunar magmatism. Geochim trace element partitioning between olivine, orthopyroxene and melt in Cosmochim Acta 206:273–295 chondrules: equilibrium values and kinetic effects. Earth Planet Sci Lett Weisberg MK, Printz M, Clayton R, Mayeda TK (1997) CV3 chondrites: three 115:177–195 subgroups, not two. Meteorit Planet Sci 32:138–139 Krot AN, Petaev MI, Scott ERD, Choi B, Zolensky ME, Keil K (1998) Progressive Wlotzka F (1993) A weathering scale for the ordinary chondrites. Meteoritics alteration in CV3 chondrites: more evidence for asteroidal alteration. 28:460 Meteorit Planet Sci 33:1065–1085 Kuehner SM, Laughlin JR, Grossman L, Johnson ML, Burnett DS (1989) Deter- mination of trace element mineral/liquid partition coefficients in melilite and diopside by ion and electron microprobe techniques. Geochim Cosmochim Acta 53:3115–3130 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Earth, Planets and Space Springer Journals

Redistribution of Sr and rare earth elements in the matrices of CV3 carbonaceous chondrites during aqueous alteration in their parent body

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Earth Sciences; Earth Sciences, general; Geology; Geophysics/Geodesy
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Abstract

We measured the abundances of Sr and rare earth elements (REEs) in the matrices of five CV3 carbonaceous chon- drites: Meteorite Hills (MET ) 00430, MET 01070, La Paz ice field (LAP) 02206, Asuka (A) 881317 and Roberts Massif (RBT ) 04143. In the MET 00430 and MET 01074 matrices, the Sr/CI and light REE (LREE, La–Nd)/CI ratios positively correlate with the amounts of Ca-rich secondary minerals, which formed during aqueous alteration in the CV3 chondrite parent body. In contrast, in the LAP 02206 and RBT 04143 matrices, although the Sr/CI ratios correlate with the amounts of Ca-rich secondary minerals, the LREE/CI ratios vary independently from the amounts of any secondary minerals. This suggests that the LREE/CI ratios in these matrices were produced prior to the parent body alteration, probably in the solar nebula. The LREE/CI ratios of the LAP 02206 and RBT 04143 matrices reveal the mixing process of matrix miner- als prior to the accretion of the CV3 chondrite parent body. The mixing degrees of matrix minerals might be different between these two matrices. Because solid materials would be mixed over time according to the radial diffusion model of a turbulent disk, the matrix minerals consisting of LAP 02206 and RBT 04143 matrices might be incorporated into their parent body with different timing. Keywords: Rare earth element, CV3 carbonaceous chondrite, Aqueous alteration, Solar nebula Introduction ordinary chondrites (e.g., Alexander 1995; Bland et  al. In water-bearing asteroids, aqueous alteration, the chem- 2005). In contrast, in primitive carbonaceous chondrites ical reaction between aqueous fluids and primary min - (e.g., CO3 and CV3), only CV3 Bali, which has similar erals formed in the solar nebula, had taken place after alteration conditions to CM2 or CR2 chondrites, shows the melting of ice due to the decay heat of short-lived higher Sr abundances of matrix compared to CI chon- 26 60 radiogenic nuclides such as Al and Fe (e.g., Brearley drite (e.g., Bland et  al. 2005). Typically, matrices in CO3 and Krot 2013). During the aqueous alteration, soluble and CV3 chondrites preserve the Sr abundance of CI elements (e.g., Sr) would be redistributed from primary chondrite (e.g., Hua et al. 1996; Bland et al. 2005; Martin minerals in the matrices, chondrules and Ca–Al-rich et  al. 2013). This indicates that elements with relatively inclusions to secondary minerals through aqueous flu - lower solubility compared with Sr (e.g., Au, Ga and Se) ids. This process would result in non-CI–chondritic Sr would not be redistributed during aqueous alteration abundances of matrices in the heavily aqueous-altered (e.g., Bland et al. 2005). carbonaceous (e.g., CM2 and CR2) and unequilibrated However, it was found that Sr is present in second- ary minerals in matrices of CV3 Allende and Vigarano chondrites (Dyl et  al. 2014). In addition, Sr abundances *Correspondence: kaorijogo@kopri.re.kr of some parts of Allende matrix are different from CI Division of Earth-System Sciences, Korea Polar Research Institute, 26 chondrite abundance (Inoue et al. 2004). Because Allende Songdomirae-ro, Yeonsu-gu, Incheon 21990, South Korea and Vigarano are typical CV3 chondrites and are not Full list of author information is available at the end of the article © The Author(s) 2018. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Jogo et al. Earth, Planets and Space (2018) 70:37 Page 2 of 9 heavily aqueous-altered as is Bali, we expect that redis- magnetite and altered silicates occur in these matrices tribution of Sr might have occurred even in the typical (Fig. 1a, b and Additional file  1: Table S1). These mineral CV3 chondrites during aqueous alteration in their parent species are similar to those of C V3 matrices (e.g., Krot OxB body. To verify this hypothesis, we measured the Sr and et al. 1998). In the LAP 02206 host matrix, Ca-pyroxene, REE (lower solubility than Sr) abundances of matrices in awaruite, Fe, Ni-sulfide, ferrous olivine, sodalite and the CV3 MET 00430, MET 01070, LAP 02206, A 881317 plagioclase were observed (Fig.  1c and Additional file  1: and RBT 04143 chondrites using secondary ion mass Table S1). These mineral species are consistent with spectrometry. those of CV3 matrices (e.g., Krot et  al. 1998). In the OxA A 881317 matrix 5, Ca-pyroxene, Ca-phosphate, relict Fe, Results Ni-metal, ferrous olivine and magnetite were observed Mineralogy of CV3 chondrites (Fig. 1d and Additional file  1: Table S1). Fe-sulfide and Fe, We performed mineralogical observations of five CV3 Ni-sulfide are rare. These mineralogical features are simi - chondrites including all CV3 subtypes: the oxidized lar to those of the C V3 matrix (e.g., Krot et  al. 1998), Ox Allende-like type (CV3 ) LAP 02206, the oxidized Bali- suggesting that the clast including the A 881317 matrix OxA like type (CV3 ) MET 01074 and CV3 MET 00430, 5 would be the CV3 clast in the CV3 A881317 brec- OxB OxB Ox Red and the reduced type (C V3 ) RBT 04143 and C V3 A cia. In the RBT 04143 matrices 5 and 6, similar primary Red Red 881317 (e.g., Weisberg et  al. 1997). The analytical meth - and secondary minerals were observed: kirschsteinite, ods are described in Additional file  1. These samples are Ca-pyroxene, Ca-phosphate, Fe, Ni-metal, kamacite, all Antarctic find-type meteorites, and their terrestrial Fe-sulfide, Fe, Ni-sulfide, ferrous olivine and magnetite weathering grades are A/B for RBT 04143, B for MET occur in these matrices (Fig.  1e, f and Additional file  1: 00430, MET 01047 and LAP 02206, and no data for A Table S1). Small Fe, Ni-sulfide grains (< 2 µm in size) are 881317 (e.g., Meteorite bulletin). A section of RBT 04143 abundant only in the RBT 04143 matrix 6 (Fig.  1f and that we studied contains Fe oxide weathering products Additional file  1: Table S1). These mineralogical fea - in cracks and fractures of the section (Additional file  1: tures are similar to those of the C V3 matrix (e.g., Krot Red Fig. S1). In contrast, sections of the other four CV3 chon- et al. 1998). We could not find any evidence of terrestrial drites do not contain such weathering products. weathering such as oxidation of opaques in the measured The general petrography of these five CV3 chondrites matrices (e.g., Wlotzka 1993). was described in Ishida et  al. (2015) and Jogo et  al. (2017). Briefly, the RBT 04143 and A 881317 chondrites Chemical compositions of the matrices are breccias consisting of many clasts (e.g., Fig. 2 in Jogo We measured the chemical compositions of six matrices et  al. 2017). A typical clast (from 0.5 to 1  mm in size) is (analytical methods are described in Additional file  1): 14 composed of chondrules and surrounding olivine-rich data from the CV3 MET 00430 host matrix, 10 data OxB fine-grained materials. The clasts are either embedded in from the CV3 MET 01070 host matrix, 11 data from OxB the host matrix or in direct contact with adjacent clasts. the CV3 LAP 02206 host matrix, 5 data from the OxA In contrast, such clasts were not observed in the LAP CV3 A 881317 matrix 5, 5 data from the CV3 RBT Ox Red 02206, MET 00430 or MET 01074 chondrites. 04143 matrix 5 and 3 data from the C V3 RBT 04143 Red For a more detailed mineralogical and chemical anal- matrix 6. We carefully chose matrix areas without Fe ysis, we selected six matrices: host matrices from the oxide weathering veins in CV3 RBT 04143 (Additional Red MET 00430, MET 01074 and LAP 02206 chondrites, one file 1: Fig. S1). matrix from the A 881317 chondrite (A 881317 matrix 5) The measured matrices have various Sr abundances and two matrices from the RBT 04143 chondrite (RBT and show some departures from CI chondrite abundance 04143 matrix 5 and matrix 6) (Fig.  1). In the RBT 04143 (Fig.  2 and Additional file  1: Table S2). The averaged Sr/ and A 881317 breccias, we chose the matrices with clear Yb ratios normalized to the CI chondrite abundance of clast boundaries in the backscattered electron images each matrix are < 0.8 or > 1.3 (Additional file  1: Table (Fig. 1). S2). The averaged Sr/CI ratios are 0.9–3.2, and only the All of the matrices we measured consist primarily of CV3 LAP 02206 host matrix and the CV3 RBT OxA Red ferrous olivine grains, but the grain sizes and porosities 04143 matrix 5 show CI chondrite abundance (averaged differ among matrices (e.g., Fig.  1). Primary and second- Sr/CI ratios of 0.9–1.0). The range of Sr/CI ratios within ary minerals occur between matrix olivine grains. Their an individual matrix is different among matrices. The species and distributions are different in each matrix. CV3 LAP 02206 host matrix, the CV3 A 881317 OxA Ox In the host matrices of MET 00430 and MET 01074 matrix 5 and the C V3 RBT 04143 matrix 5 show Red chondrites, similar secondary minerals were observed; moderately broad Sr/CI ratios with a standard devia- Ca-pyroxene, Fe, Ni-sulfide, ferrous olivine, fayalite, tion of < 0.4. The rest of the CV3 MET 00430 and the OxB Jogo et al. Earth, Planets and Space (2018) 70:37 Page 3 of 9 CV3 MET 01074 host matrices and the C V3 RBT clear correlation between La/CI ratios and modal abun- OxB Red 04143 matrix 6 show broad Sr/CI ratios with a standard dances of magnetite in these matrices (Table 1 and Addi- deviation of > 0.8. tional file 1: Fig. S3). The LREE abundances of measured matrices are also various and show some departures from CI chondrite Discussion abundance (Fig.  2 and Additional file  1: Table S2). The The effect of terrestrial weathering on matrix Sr and LREE averaged LREE/CI ratios of the CV3 A 881317 matrix abundances Ox 5 and the C V3 RBT 04143 matrices 5 and 6 are similar The weathering grades of our samples are A/B to B, Red to CI chondrite abundance (e.g., averaged La/CI ratios of whereas no Fe oxide weathering products were observed 1.0–1.4). The rest of the CV3 MET 00430 and CV3 in their matrices (e.g., Fig. 1); minor Fe oxide weathering OxB OxB MET 01074 host matrices and the CV3 LAP 02206 veins occur only in C V3 RBT 04143 (Additional file  1: OxA Red host matrix show higher LREE/CI ratios than CI chon- Fig. S1). In weathered Antarctic meteorites, the precipi- drite abundance (e.g., averaged La/CI ratios of 1.6–1.8). tation of Fe oxide weathering products is confined to The ranges of LREE/CI ratios are narrow in the CV3 fractures through the meteorite and voids in the fusion OxA LAP 02206 host matrix, the C V3 A 881317 matrix 5 crust, rather than being pervasively distributed through- Ox and CV3 RBT 04143 matrix 5 (e.g., standard deviation out the matrix (Abreu and Brearley 2010). The low per - Red of La/CI ratios of ~ 0.2–0.3), but they are broad in the meability of the matrix might limit the incorporation CV3 MET 00430 and CV3 MET 01074 host matri- of terrestrial water into the matrices and prevent them OxB OxB ces and the C V3 RBT 04143 matrix 6 (e.g., standard from experiencing terrestrial weathering. A similar pro- Red deviation of La/CI ratios of ~ 0.5–0.7). Small Ce anoma- cess might have occurred in the matrices we measured lies are detected in each matrix (Fig.  2). The Ce anoma - and result in no precipitation of weathering products in lies are not correlated with the matrix compositions with them because CV3 matrices would have low permeabil- respect to soluble elements such as Ca, Sr and Nd (Addi- ity (Bland et al. 2009). Based on the weathering scale for tional file 1: Fig. S2). ordinary chondrites (e.g., Wlotzka 1993), the weathering The abundances of middle to heavy REEs (MREE and grades of the sections we studied are estimated to be W1 HREE; Nd–Lu) are less various compared to those of for CV3 RBT 04143 with minor Fe oxide weathering Red LREEs (Fig.  2). The MREE/CI and HREE/CI ratios are veins and W0 for the rest of the samples with no Fe oxide consistent with the errors within individual matrices weathering products. and among different matrices (MREE/CI = 0.2–3.6 and The measured matrices with weathering grade W1 HREE/CI = 0.5–2.4 in all matrices; Fig.  2 and Additional show similar or lower Ca, Sr and REE abundances com- file  1: Table S2). Most of the matrices show Eu anoma- pared to those with weathering grade W0 or matrices in lies with large uncertainties; both positive and negative the unweathered fall-type CV3 chondrites (Fig.  2g, Hua anomalies were detected in each matrix (Fig. 2). et  al. 1996; Inoue et  al. 2004; Bland et  al. 2005; Martin et  al. 2013). This may suggest that leaching of soluble Correlations between Sr/CI and La/CI ratios and chemical elements might occur during terrestrial weathering in composition of the matrix the matrices with weathering grade W1. However, they Correlations between the Sr/CI and La/CI (representa- do not show preferential depletion in soluble Ca, Sr and tive of REEs) ratios and chemical compositions of matrix LREEs compared to the find-type CV3 matrices. The have been investigated (Table  1, Fig.  3 and Additional depleted elements are Ce, Pr, Sm, Tb, Ho and Tm, which file  1: Fig. S3). For the Sr/CI ratio and Ca contents, all do not have high solubility in water, suggesting that sol- matrices except the CV3 RBT 04143 matrix 6 show uble element abundances of the matrices with weather- Red strong positive correlations with correlation coefficients ing grade W1 would not be disturbed during terrestrial of R ≧ 0.7. For the La/CI ratio and Ca contents, only host weathering. 3+ matrices in the CV3 MET 00430 and CV3 MET In addition, in Antarctic achondrites, oxidation of Ce OxB OxB 4+ 01074 chondrites show moderate to strong positive cor- to the more insoluble Ce caused the separation of this relations with correlation coefficients of R ≧ 0.6. For the element from the other LREEs, resulting in Ce anoma- La/CI ratio and the other elements’ contents, only the lies (e.g., Floss and Crozaz 1991; Crozaz et al. 2003). The CV3 A 881317 matrix 5 shows a moderate positive cor- leaching of soluble elements from achondrites would Ox relation between La/CI and P contents with a correlation cause low soluble element abundances with positive Ce coefficient of R ~ 0.6. The rest of the CV3 RBT 04143 anomalies. We expect that a similar process would occur Red matrices 5 and 6 and the C V3 LAP 02206 host matrix in the CV3 matrices we measured. However, a tendency OxA do not show strong positive correlations between La/CI for positive Ce anomalies to occur at low Ca, Sr and LREE and chemical compositions (R ≦ 0.3). There is also no concentrations was not found in the measured matrices Jogo et al. Earth, Planets and Space (2018) 70:37 Page 4 of 9 Fig. 1 Backscattered electron images of CV3 matrices: a CV3 MET 00430 host matrix; b CV3 MET 01074 host matrix; c CV3 LAP 02206 host OxB OxB OxA matrix; d CV3 A 881317 matrix 5; e CV3 RBT 04143 matrix 5; f CV3 RBT 04143 matrix 6. Clast boundaries between CV3 RBT 04143 matrices Ox Red Red Red 5 and 6 are shown by dotted lines in e and f. The weathering grade (A/B or B and W0 or W1) and matrix type (type 1 or 2) are also shown. All images are presented at the same magnification. awr awaruite, Ca -phs Ca-phosphate, Ca-px Ca-pyroxene, Fe-ol ferrous olivine, slf sulfide, kir kirschsteinite, mgt magnetite, ol olivine, pent pentlandite, pl plagioclase (Additional file  1: Fig. S2). This indicates the same con - preterrestrial processes, i.e., nebular or asteroidal altera- clusion that Ca, Sr and LREEs would not be leached from tion processes. Although only the CV3 RBT 04143 Red the matrices with weathering grade W1 during terrestrial matrix 6 shows a negative correlation between Sr abun- weathering. Therefore, the Ca, Sr and LREE abundances dances and Ce anomalies, it will not be discussed further of the matrices we measured would probably reflect because of its small number of data. Jogo et al. Earth, Planets and Space (2018) 70:37 Page 5 of 9 Fig. 2 CI-normalized REE, Sr and Ca abundances of CV3 matrices (a–f). Representative error bars (1σ) are shown in each matrix. Average composi- tions of find-type CV3 matrices [weathering grades of B and W0 (red), A/B and W1 (blue) and W0 (black)] and fall-type CV3 matrices (green) are shown in (g) Redistribution of Sr and LREEs in the matrix classified into two types (Table  1): [type 1] CV3 MET OxB during aqueous alteration in the parent body 00430 and CV3 MET 01074 host matrices, char- OxB Based on the correlation between the Sr/CI, La/CI ratio acterized by moderate to strong positive correlations and the Ca contents of a matrix, the matrices could be between the Sr/CI and La/CI ratios and the Ca contents Jogo et al. Earth, Planets and Space (2018) 70:37 Page 6 of 9 (R ~ 0.6–0.9); and [type 2] C V3 LAP 02206 host OxA matrix, CV3 A 881317 matrix 5 and C V3 RBT 04143 Ox Red matrix 5, characterized by strong positive correlation between the Sr/CI ratio and Ca contents (R ~ 0.7–0.9) but no strong correlation between the La/CI ratio and Ca contents (R ~ 0.0–0.2). We will discuss whether any redistribution of Sr and LREEs occurred during aque- ous alteration in type 1 and 2 matrices in the following sections. Type 1 matrix (CV3 MET 00430 and CV3 MET OxB OxB 01074 host matrices) The Sr/CI and La/CI ratios of a type 1 matrix are positively correlated with the Ca con- tents of the matrix (Table 1 and Fig. 3). This implies that the amounts or mineral species of the Ca-rich phase con- trol the Sr/CI and La/CI ratios of a type 1 matrix. The Ca- rich phase in a type 1 matrix is Ca-pyroxene (Additional file  1: Table S1 and Fig. 1a, b), which is a secondary min- eral formed during aqueous alteration in the CV3 chon- drite parent body (e.g., MacPherson and Krot 2014). The Sr and LREE partition coefficients in Ca-pyroxene from melt are highest among those in secondary minerals in a type 1 matrix (e.g., Kuehner et  al. 1989; Nielsen et  al. 1992; Kennedy et  al. 1993; Prowatke and Klemme 2006; Sun et  al. 2017, Additional file  1: Fig. S4). This suggests that the Sr and LREEs in aqueous fluids would be prefer - entially incorporated into Ca-pyroxene during its forma- Fig. 3 Ca (wt%) versus Sr/CI (blue) and Ca/CI (red) plots of CV3 matri- tion. Since the amounts of Ca-pyroxene minerals control ces. Error bars are 1σ. R : correlation coefficient the Sr and LREE abundances of the matrix, the Sr and LREE abundances of a type 1 matrix would be disturbed during aqueous alteration in the parent body. abundance of a type 2 matrix would be disturbed during Type 2 matrix (CV3 LAP 02206 host matrix, CV3 A aqueous alteration in the parent body. OxA Ox 881317 matrix 5 and CV3 RBT 04143 matrix 5) The Regarding the lack of a strong positive correlation Red Sr/CI ratios of the type 2 matrix are positively correlated between the La/CI ratio and Ca contents of the matrix, with the Ca contents of the matrix, but the La/CI ratios there could be two possible explanations: (1) La in the are not (Table 1 and Fig. 3). This implies that the amounts aqueous fluids was incorporated into Ca-poor second - or mineral species of the Ca-rich phase control the Sr/CI ary minerals, and the amounts of such minerals con- ratios of the matrix, but the La/CI ratios of the matrix are trolled the LREE abundances of matrix or (2) La was not controlled by other factors. dissolved in the aqueous fluids. There are no secondary minerals that have higher LREE partition coefficients Concerning positive correlations between the Sr/ than those of the Ca-rich secondary minerals in a type CI ratios and Ca contents, we adopt the same logic for 2 matrix (Additional file  1: Table S1 and Fig. S4). Thus, explaining the Sr abundance of type 1 matrix. The Ca- case 1 would not be possible. Therefore, we propose rich phases in type 2 matrix are kirschsteinite, Ca- case 2 as a mechanism for explaining the La/CI ratios of pyroxene, Ca-phosphate and plagioclase (Fig.  1c–e and the type 2 matrix. The lack of any clear positive correla - Additional file  1: Table S1), which are all secondary min- tions between La/CI ratios and chemical compositions erals (e.g., Krot et al. 1998; MacPherson and Krot 2014). of type 2 matrix would also support case 2 (Table  1 and Because the Sr partition coefficients in these minerals are Additional file  1: Fig. S3). Although the CV3 A 881317 Ox high (Additional file  1: Fig. S4), the Sr in aqueous fluids matrix 5 shows moderate positive correlation between would be preferentially incorporated into them during La/CI ratios and P contents (R ~ 0.6), the range of P con- their formation. Since the amounts of these secondary tent is too narrow to discuss the correlation (e.g., Addi- minerals control the Sr abundance of the matrix, the Sr tional file 1: Fig. S3-2a). Jogo et al. Earth, Planets and Space (2018) 70:37 Page 7 of 9 Table 1 Correlation coefficient (R ) of Sr/CI and La/CI ratios and chemical compositions of CV3 matrices N: number of data Negative correlation The correlations between Sr/CI, La/CI and the chemi - (e.g., Floss and Crozaz 1991; Bland et al. 2005). The LREE cal composition of type 1 and 2 matrices suggest that the abundances of type 2 matrix (the C V3 LAP 02206 OxA Sr abundances were disturbed in both type 1 and 2 matri- host matrix and the CV3 RBT 04143 matrix 5) would Red ces (including all C V3, CV3 and C V3 subtypes), not be disturbed during terrestrial weathering or aque- OxA OxB Red but those of LREEs were disturbed only in the type 1 ous alteration in their parent body (“The effect of ter - matrix (the C V3 subtype). There are also some CV3 restrial weathering on matrix Sr and LREE abundances” OxB chondrites (including all C V3, CV3 and CV3 and “Redistribution of Sr and LREEs in the matrix dur- OxA OxB Red subtypes) with Sr and REE abundances of matrices ing aqueous alteration in the parent body” sections). This that would not be disturbed during aqueous alteration then implies that their LREE abundances would reflect (e.g., Bland et  al. 2005). These findings may suggest that the nebular process prior to the accretion of their parent there is no correlation between CV3 subtypes (C V3 , body. OxA CV3 and CV3 ) and that there is some redistribu- In the CV3 LAP 02206 host matrix, the LREE pat- OxB Red OxA tion of Sr and/or LREE abundances in CV3 matrices. terns are similar among measurement spots: All are Because the dissolution of Sr and La in aqueous fluids convex downward with lower abundances of Ce and Pr would reflect the aqueous alteration conditions (e.g., than La and Nd (Fig.  2c). This may imply that (1) all the temperature, pH and chemical composition of fluids, matrix minerals experienced similar thermal processes Michard 1989), the lack of a correlation between sub- in the solar nebula or (2) although each matrix mineral types and Sr and La dissolution may imply that aqueous was formed by different nebular processes, they were alteration conditions might be various even in the same well mixed prior to the accretion to their parent body. subtype of CV3 chondrites. In contrast, in the C V3 RBT 04143 matrix 5, the Red LREE patterns are slightly different among measurement Implications for the CV3 chondrite parent body accretion spots (Fig.  2e). This may imply that the matrix minerals process retained their heterogeneity when the C V3 RBT 04143 Red The chemical compositions of CV3 matrices could reflect matrix accreted to its parent body. nebular processes, aqueous alteration in the CV3 chon- The specific minerals or nebular processes that con - drite parent body and/or terrestrial weathering processes trol the LREE abundances of matrices could not be Jogo et al. Earth, Planets and Space (2018) 70:37 Page 8 of 9 Author details constrained in this study. Inoue et  al. (2004) suggested Division of Earth-System Sciences, Korea Polar Research Institute, 26 the existence of some unknown LREE-enriched compo- Songdomirae-ro, Yeonsu-gu, Incheon 21990, South Korea. Kochi Institute nents in CV3 Allende matrices. The LREE abundances for Core Sample Research, JAMSTEC, B200 Monobe, Nankoku, Kochi 783-8502, Japan. Division of Earth and Planetary Materials Science, Tohoku University, of matrices might reflect the complementary chondrule/ Sendai, Miyagi 980-8578, Japan. Unit of Antarctic K-route Expedition, Korea matrix formation process in which the chondrules and Polar Research Institute, 26 Songdomirae-ro, Yeonsu-gu, Incheon 21990, South matrix formed complementarily from a single LREE res- Korea. ervoir (e.g., Inoue et al. 2004; Bland et al. 2005). Acknowledgements The different LEE patterns of the CV3 LAP 02206 OxA The meteoritic samples were provided by the National Institute of Polar and the C V3 RBT 04143 matrices may be explained by Research (Japan) and the NASA Johnson Space center. We thank Ms. Moon Red and Dr. Park for the support to use SEM and FE-EPMA. We appreciate the the radial diffusion model of a turbulent disk (Cuzzi et al. detailed comments from Dr. Fujiya and an anonymous reviewer. We also thank 2010). This could introduce the difference in the degree of Prof. Noguchi for the editorial handling. material mixing with time in the solar nebula. In the case Competing interests of (1), the CV3 LAP 02206 matrix would accrete to its OxA The authors declare that they have no competing interests. parent body before mixing with other matrix minerals. In the case of (2), matrix minerals were well mixed when Availability of data and materials The data and materials are available upon request from the corresponding the CV3 LAP 02206 host matrix accreted to its parent OxA author (kaorijogo@kopri.re.kr). body. In contrast, the matrix minerals retained their het- erogeneity when the C V3 RBT 04143 matrix accreted. Consent for publication Red Not applicable. To produce the difference in mixing degrees of matrix minerals, the matrix minerals consisting of CV3  LAP OxA Ethics approval and consent to participate 02206 and C V3   RBT 04143 matrices might be incor- Not applicable. Red porated into their parent body with different timing. Funding This work was supported by KOPRI project PM17030. MI was supported by the Summary JSPS Grants-in-Aid for Science Research (no. 26287142) from the Shimadzu Science Foundation (2016). This work was supported in part by the Kochi Core The Sr and REE abundances of six matrices in five CV3 Center Open Facility System under the MEXT foundation. chondrites were measured. The correlations between the Sr, La and Ca abundances of the matrices suggest that Sr Publisher’s Note and LREEs would have been redistributed in the MET Springer Nature remains neutral with regard to jurisdictional claims in pub- 00430 and MET 01070 matrices during aqueous altera- lished maps and institutional affiliations. tion in their parent body. Only the LAP 02206 and RBT Received: 21 December 2017 Accepted: 26 February 2018 04143 matrices would preserve the LREE abundances that reflect nebular processes. 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Published: Mar 12, 2018

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