The 12th Symposium on Polar Science
15 – 18 November 2021
National Institute of Polar Research
Research Organization of Information and Systems

Session OA
Antarctic meteorites
Program and Abstracts
Convener : Naoya Imae (NIPR)

【OA】Antarctic meteorites
ScopesThis session is held to present recent research outcomes for Antarctic meteorites and micrometeorites. It will also be an
opportunity for general and topical discussion sessions dealing with new data from non-Antarctic meteorites andextraterrestrial materials, and related experimental and theoretical works.
Convener : Naoya Imae (NIPR)

Real-time Oral presentations (13:10 – 16:15)

Date: Thu. 18 November
Chair: Akira Yamaguchi (NIPR)

13:10 - 13:15 Opening
Lithium, and boron isotopic compositions of
OAo1 13:15 - 13:30 chondrule olivine from Yamato 81020, Asuka
12236 and QUE 97008 chondrites

OAo2 13:30 - 13:45

Tarda: A highly aqueously altered meteorite
from an outer Solar System asteroid?

OAo3 13:45 - 14:00

Carbonate minerals in the highly-altered A12248 CM chondrite

Identifying characteristics of primordial andsecondary products in SOM mass distributions
OAo4 14:00 - 14:15
extracted from CI, C2 ungrouped, CR and CM
chondrites
OAo5 14:15 - 14:30

High-pressure minerals in CB carbonaceouschondrites

OAo6 14:30 - 14:45

Infrared spectroscopy of astromaterials withnanoscale resolution

Akira Yamaguchi (NIPR), Naoya Imae (NIPR)*Nozomi Matsuda (UCLA) and Ming-Chang Liu (UCLA)OA_Matsuda_00591_01* Devin L. Schrader (Center for Meteorite Studies,
School of Earth and Space Exploration, Arizona State
University), Jemma Davidson (Center for Meteorite
Studies, School of Earth and Space Exploration, Arizona
OA_Schrader_00141_01
State University), Dionysis Foustoukos (Earth andPlanetary Laboratory, Carnegie Institution for Science),
Conel M. O’D. Alexander (Earth and Planetary
Laboratory, Carnegie Institution for Science) andThomas J. Zega (Lunar and Planetary Laboratory,*Kaitlyn A. McCain (University of California at Los
Angeles), Ming-Chang Liu (University of California at
OA_Mccain_00499_01
Los Angeles) and Kevin D. McKeegan (University ofCalifornia at Los Angeles)*J.Isa (ELSI), F.-R. Orthous-Daunay (IPAG), V. Vuitton(IPAG), L. Bonal (IPAG), O. Poch (IPAG)
and M. Zolensky (JSC)*Masaaki Miyahara (Hiroshima Univ.), Eiji Ohtani(Tohoku Univ.), Akira Yamaguchi (NIPR) and Naotaka
Tomioka (JAMSTEC)*Mehmet Yesiltas (Kirklareli University), Timothy D.
Glotch (Stony Brook University) and Bogdan Sava
(Neaspec GmbH)OA_Isa_00619_01

OA_Miyahara_00204_01

OA_Yesiltas_00557_01

Formation of spherical iron oxide minerals by*Huimin Shao (Kumamoto University), Hiroshi Isobeoxidative hydrothermal alteration from metallic
OA_Shao_00518_01
OAo7 14:45 - 15:00(Kumamoto University), Ginga Kitahara (Kumamoto
spherules: Implications for hematite spherules
University) and Akira Yoshiasa (Kumamoto University)and surface conditions of Mars
15:00 - 15:15 Break
Chair: Naoya Imae (NIPR)*Atsushi Takenouchi (The Kyoto University Museum,Comprehensive study of shock metamorphism Kyoto University), Hirochika Sumino (Graduate School
OA_Takenouchi_00593_01
OAo8 15:15 - 15:30
of Arts and Science, The University of Tokyo) and Akira
and 40Ar/39Ar ages in ordinary chondrites
Yamaguchi (National Instutute of Polar Research)*Ryoga Maeda (Virije Universiteit Brussel), Steven
Goderis (Virije Universiteit Brussel), Thibaut Van Acker
The effect of fluid mobilization on the budget(Ghent University), Frank Vanhaecke (Ghent
OA_Maeda_00288_01
OAo9 15:30 - 15:45 and distribution of rare earth elements in
University), Akira Yamaguchi (National Institute of
Antarctic H chondrites
Polar Research ), Vinciane Debaille (Universite libre deBruxelles) and Philippe Claeys (Vrije Universiteit*Rei Kanemaru (Institute of Space and Astronautical
Thermal and shock history of diogenites based Science), Akira Yamaguchi (National Institute of PolarOA_Kanemaru_00618_01
OAo10 15:45 - 16:00
on the occurrence of silica minerals
Research), Naoya Imae (National Institute of Polar
Research) and Atsushi Takenouchi (Kyoto University)Determination of the real size distribution of
OAo11 16:00 - 16:15 chondrules based on the measured size
distributions in thin sections*Jozsef Vanyo (Eszterhazy Karoly Catholic University,
Faculty of Natural Sciences, Institute of Chemistry andPhysics, Department of Physics), Arnold Gucsik(Eszterhazy Karoly Catholic University, Faculty of
Natural Sciences, Institute of Chemistry and Physics,
Department of Physics), Arpad Csamer (University of
Debrecen, Cosmochemistry Research Group,
Department of Mineralogy and Geology, Institute for
Earth Sciences) and Jan Sztakovics (Eszterhazy Karoly
Catholic University, Faculty of Natural Sciences,
Institute of Chemistry and Physics, Department of

OA_Vanyo_00562_01

Poster presentations (1 November - 18 November)

OAp1

OAp2

OAp3
OAp4

OAp5

OAp6

OAp7

OAp8

Multiscale characterization of Asuka 12169
meteorite - rehearsal of Hayabusa2 returned
sample analysis -*Masayuki Uesugi (JASRI/SPring-8), M. Ito (JAMSTEC
Kochi), N. Tomioka (JAMSTEC Kochi), N. Imae (NIPR), A.
Yamaguchi (NIPR), M. Kimura (NIPR), N. Shirai (Tokyo
Met. Univ.), T. Ohigashi (UVSOR/IMS), M-C. Liu (UCLA),
R.C. Greenwood (Open Univ.), K. Uesugi (JASRI/SPringOA_Uesugi_00609_018), A. Nakato (JAXA-ISAS), K. Yogata (JAXA-ISAS), H.
Yuzawa (UVSOR/IMS), Y. Kodama (MWJ), M. Yasutake(JASRI/SPring-8), K. Hirahara (Osaka Univ.), A. Takeuchi(JASRI/SPring-8), I. Sakurai (Nagoya Univ.), I. Okada(Nagoya Univ.), Y. Karouji (JAXA-ISAS), T. Yada (JAXAISAS)and (NIPR),
M. AbeA.
(JAXA-ISAS)*N. Imae
Yamaguchi (NIPR), M. Kimura(NIPR), M. Ito (JAMSTEC Kochi), N. Tomioka (JAMSTEC
Kochi), M. Uesugi (JASRI/SPring-8), N. Shirai (Tokyo
Met. Univ.), T. Ohigashi (UVSOR/IMS), M-C. Liu (UCLA),
Characterizing the Ryugu samples using the
R.C. Greenwood (Open Univ.), K. Uesugi (JASRI/SPringOA_Imae_00205_02
laboratory-based XRD and the meteorite
8), A. Nakato (JAXA-ISAS), K. Yogata (JAXA-ISAS), H.
collections at NIPR
Yuzawa (UVSOR/IMS), Y. Kodama (MWJ), M. Yasutake(JASRI/SPring-8), K. Hirahara (Osaka Univ.), A. Takeuchi(JASRI/SPring-8), I. Sakurai (Nagoya Univ.), I. Okada(Nagoya Univ.), Y. Karouji (JAXA-ISAS), T. Yada (JAXAWhat is type 3.0 of chondrites?
*Makoto Kimura (National Institute of Polar Research) OA_Kimura_00008_01
Chemical analyses of Fe - rich chondrule phases *P. Futo (University of Debrecen, Cosmochemistryin Kaba (CV3) carbonaceous - chondrite.
Research Group, Department of Mineralogy and
OA_Futo_00080_02
Implications on the bulk elemental composition Geology) and A. Gucsik (Faculty of Natural Sciences,of terrestrial planetary cores
Institute of Chemistry and Physics, Department of*Peter Futo (University of Debrecen, Cosmochemistry
On the bulk mineralogical composition of
Research Group, Department of Mineralogy andcarbonaceous chondrites in low-Mg/Si planetary Geology) and Arnold Gucsik (Eszterházy Károly Catholic OA_Futo_00080_01
systems
University, Faculty of Natural Sciences, Institute ofChemistry and Physics, Department of Physics)*Keisuke Narahara (Department of Chemistry,
Graduate School of Science, Tokyo University of
Science), Shu-hei Urashima (Department of Chemistry,
An attempt for estimating aqueous alteration
Graduate School of Science, Tokyo University of
OA_Narahara_00547_01
environment from Raman spectra of iron sulfide Science), Akira Yamaguchi (National Institute of Polar
Research), Naoya Imae (National Institute of Polar
Research) and Hiroharu Yui (Department of Chemistry,
Graduate School of Science, Tokyo University of*Aruto Kashima (Tokyo University of Science), Shu-hei
Identifying Polymorphs of Serpentine with
Urashima (Tokyo University of Science) and Hiroharu OA_Kashima_00524_01
Micro-Raman Spectroscopy
Yui (Tokyo University of Science)*Viktor H Hoffmann (Faculty of Geosciences, Dep.
Earth and Environmental Sciences, Univ. Munich /Germany), Phillipe Schmitt-Kopplin (Helmholtz-Center,
Erg Chech 002 - A New Member of the (Trachy-)
Munich, Germany), Melanie Kaliwoda (Mineralogical OA_Hoffmann_00587_01
Andesite Meteorite Clan
State Collection Munich, SNSB, Germany) and
Wolfgang Schmahl (Faculty of Geosciences, Dep. Earthand Environmental Sciences, Univ. Munich, Germany)

OAp9

Chemical classifications of nine new ironmeteorites from Yamato Mountains, Balchen
and Nansen Ice field*Naoki Shirai (Tokyo Metropolitan University), Akira
Yamaguchi (National Institute of Polar Research),
Makiko Haba (Tokyo Institute of Technology) and Shun OA_Shirai_00275_01
Sekimoto (Institute for Integrated Radiation and
Nuclear Science, Kyoto University)

Lithium, and boron isotopic compositions of chondrule olivine from Yamato 81020, Asuka 12236
and QUE 97008 chondrites

1

Nozomi Matsuda1and Ming-Chang Liu1
Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA90095, USA

Introduction:
How the Solar System derived its boron isotopic composition of 11B/10B = 4 (inferred from the CI chondrites; Zhai et al.,1996) is still poorly understood. It is known that the majority of boron in the Galaxy is produced by spallation reactions
between the Galactic Cosmic Rays (GCRs) and C-N-O nuclei in the interstellar medium (ISM), but the resulting 11B/10B ratioof 2.5 is significantly lower than the Solar System average (and elsewhere in the solar neighborhood), indicating that extra 11B
was added during or prior to Solar System formation (e.g., Reeves et al., 1970; Meneguzzi et al., 1971). Two nucleosynthetic
processes capable of yielding components with high 11B/10B (>4) include low-energy (<10 MeV) irradiation (Bloemen et al.,1994) and the neutrino process during a supernova explosion (e.g., Yoshida et al., 2005); however, it is not clear which of thetwo sources was the dominant one. Lithium could help shed light on this question because this element is co-produced
alongside boron by these processes with markedly different production ratios. Irradiation, regardless of the projectile energies,
yields 7Li/6Li = 1.5 (e.g., Meneguzzi., 1971), whereas the neutrino process makes almost pure 7Li (7Li/6Li >1,000) (e.g.,
Woosley et al., 1990). Therefore, a quantitative understanding of the relationship between 7Li/6Li and 11B/10B in the nebula canhelp better understand the distribution of the latter in the solar nebula from which the origin of 11B-rich components could beconstrained. Although there have been several studies about Li and B isotopes in chondrite components, only Chaussidon andRobert (1998) reported a correlated analysis result of the two systems in 3 chondrules from the ordinary chondrite Semarkona.
In this study, we expand the correlated Li-B isotope measurements to chondrules from other pristine chondrites to better assessthe distribution of 11B/10B in the nebula. Some preliminary results are reported here.
Sample and analytical methods:
Polished thin sections of Yamato (Y) 81020 (CO3.05), Asuka (A) 12236 (CM2.9), and QUE 97008 (L3.05) chondrites
were examined to identify Type I porphyritic olivine-pyroxene (POP) chondrules through textures and chemical compositions
by using a scanning electron microscope (SEM, Tescan Vega) equipped with an energy dispersive spectrometer (EDS) at
UCLA. We focused on highly forsteritic olivine because it excludes beryllium, making its Li and B isotopes free of radiogenic
7
Li and 10B from the decay of short-lived 7Be and 10Be, respectively. Even though the chondrules were selected from some of
the most pristine chondrules, to ensure they have not been affected by parent body alteration, we first performed high precision
3-oxygen isotope measurements with the CAMECA ims-1290 ion microprobe, and then Li-B isotope analyses, all in
multicollection mode.
Result and discussion:
All three chondrules studied here belong to Type I POP and appear to have internally homogeneous D17O, suggestive of theabsence of aqueous alteration effects. The chondrule in Y-81020 contains forsteritic olivine characterized by D17O value of ~-5.1 ± 0.8‰ (2SD) and low-Ca pyroxene layers along the chondrule periphery. d7Li in olivine ranges from 6.4‰ to 15.5‰,
while d11B shows a large spread ranging from -6.8‰ to 43.9‰. The A-12236 chondrule consists of olivine (D17O values of ~-4.8 ± 0.6‰ (2SD)) and low-Ca pyroxene phenocrysts. The d7Li and d11B values in olivine are in the range of -15.3‰ to
12.6‰ and -2.3‰ to 36.4‰, respectively. The QUE 97008 chondrule shows a similar texture to the chondrule in Y-81020,
and its olivine has an average D17O value of ~1.0 ± 0.9‰ (2SD). Olivine shows a d7Li variation from 3.9‰ to 25.1‰, and alarger d11B range of 4.9‰ to 50.8‰. We will discuss the meaning of d7Li and d11B variations in these chondrules in themeeting.
References:
Bloemen H., Wijnands R., Bennett K., Diehl R., Hermsen W., Lichti G., Morris D., Ryan J., Schonfelder V., Strong A. W.,
Swanenburg B. N., de Vries C. and Winkler C., COMPTEL observations of the Orion complex: evidence for cosmic-ray
induced gamma-ray lines, Astron. Astrophys. 281, L5–L8, 1994.
Chaussidon M. and Robert F., 7Li/6Li and 11B/10B variations in chondrules from the Semarkona unequilibrated chondrite, Earth
Planet. Sci. Lett. 164, 577–589, 1998.
Meneguzzi M., Audouze J. and Reeves H, The production of the elements Li, Be, B by galactic cosmic rays in space and its
relation with stellar observations, Astron. Astrophys. 15, 337–359, 1971.
Reeves H., Fowler W. A. and Hoyle F., Galactic cosmic ray origin of Li, Be and B in stars, Nature 226, 727–729, 1970.

Woosley S. E., Hartmann D. H., Hoffman R. D. and Haxton W. C., The n-process, Astrophys. J. 356, 272–301, 1990.
Yoshida T., Kajino T. and Hartmann D. H., Constraining the spectrum of supernova neutrinos from ν-process induced lightelement synthesis, Phys. Rev. Lett. 94, 231101, 2005.
Zhai M., Nakamura E., Shaw D. M. and Nakano T., Boron isotope ratios in meteorites and lunar rocks, Geochim. Cosmochim.
Acta 60, 4877–4881, 1996.

Tarda: A highly aqueously altered meteorite from an outer Solar System asteroid?
Devin L. Schrader1, Jemma Davidson1, Dionysis Foustoukos2, Conel M. O’D. Alexander2, and Thomas J. Zega3.
1

Center for Meteorite Studies, School of Earth and Space Exploration, Arizona State University, 781 East Terrace
Road, Tempe, AZ 85287, USA.
2
Earth and Planetary Laboratory, Carnegie Institution for Science, 5241 Broad BranchRoad, Washington, DC 20015, USA.
3
Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona 85721, USA.

Introduction: Tarda is an ungrouped type 2 carbonaceous (C2-ung) chondrite that fell in Morocco on August 25th, 2020 near
the village of Tarda (Gattacceca et al., 2021). King et al. (2021) found that Tarda is: (1) dominated by phyllosilicates, with minor
amounts of olivine, magnetite, Fe-sulfides, and dolomite; (2) is distinct from CI and CY chondrites; and (3) displays no evidence
for heating. Based on bulk isotopic compositional similarities with Tagish Lake, King et al. (2021) and Marrocchi et al. (2021)
concluded that Tarda is similar to the C2-ung Tagish Lake and the Tagish Lake-like meteorites MET 00432 and WIS 91600(Hiroi et al., 2008; Nakamura et al., 2013; Yamanobe et al., 2018; Ushikubo and Kimura, 2021). These Tagish Lake-like
meteorites may be samples from D-type asteroid(s), which potentially formed in the outer Solar System between 8 and 13 AU(Hiroi et al., 2008; Yamanobe et al., 2018; Bryson et al., 2020; Marrocchi et al., 2021). These four similar carbonaceouschondrites are more numerous than the three samples required to define a grouplet, and only one meteorite shy of the five required
to define a new meteorite group. To further constrain the compositions and petrology of this rare material, we determined thepetrography, bulk H-C-N isotopic compositions, and in situ chemical compositions of metals, sulfides, and chondrule silicates.
Samples and Analytical Procedure: We analyzed two polished mounts of Tarda prepared from two separate stones (ASU
2149_C1 and 2149_C2) that were collected within days of the fall. X-ray element maps, high-resolution electron images, andchemical compositions were obtained with the JEOL-8530F Hyperprobe electron microprobe analyzer (EPMA) at Arizona State
University (Figs. 1 and 2) and the Cameca SX-100 EPMA at the University of Arizona (UA), following procedures described in
Schrader and Zega (2019). Chondrule sizes were measured in full polished section backscattered electron images and X-ray
element maps using image measurement tools in Adobe Photoshop®. Bulk H, C, and N abundances and isotopic compositions
were determined from a 1.03 gram homogenized interior sample (no fusion crust) at Carnegie Institution for Science following
procedures of Alexander et al. (2007).
Results: Tarda has a bulk isotopic and elemental composition of
d13C = 8.0‰ (4.17 wt.% C), d15N = 62‰ (0.297 wt.% N), and dD= 608‰ (0.916 wt.% H), yielding a bulk C/H (wt.%) ratio of 4.55.
The in situ mineral compositions and petrography of the twopolished mounts are indistinguishable from one another,
therefore, mineral compositions and petrographic observations
are presented together. We identified 18 FeO-poor (type I) andtwo FeO-rich (type II) chondrules, all of which are porphyritic
and highly aqueously altered (no remaining unaltered glass andaltered phenocrysts). One type II chondrule is nearly completely
pseudomorphically replaced by phyllosilicates. Type II
chondrules are significantly less abundant than type I chondrules(e.g., Fig. 1). Chondrule sizes of the twenty chondrules measured
Figure 1. FeMgSi RGB X-ray element map of Tarda.
ranged from 0.11 to 1.30 mm (mean 0.27±0.12; mean±2SE).
Many FeO-poor olivine fragments were observed in the matrix, which we conclude are fragments of type I chondrules, but theirsizes were not measured. The composition of chondrule olivine is Fa0.6–55.7, with Fe/Mn ratios ranging from 5–134 (# analyses =n = 65). The Fe-sulfides observed include both Fe-depleted pyrrhotite (mean Fe/S at.% ratio = 0.87, n= 14) and pentlandite (n =18). Rare Fe,Ni metal in a type I chondrule was analyzed, with Ni = 5.6 – 6.2 wt.% and Co = 0.20 – 0.24 wt.% (n = 2).
Discussion: The bulk isotopic and elemental compositions of H, C, and N indicate that Tarda is very similar to analyses of
Tagish Lake from Alexander et al. (2012), similar to the observation of Marrocchi et al. (2021). The mean at.% Fe/S ratio of Nipoor (<1 wt.% Ni) pyrrhotite in Tarda is 0.87, which indicates a high degree of aqueous alteration consistent with that seen in
CM1/2 and CI chondrites by Schrader et al. (2021). Pyrrhotite-pentlandite geothermometry via phase diagram analysis (e.g.,Schrader et al., 2016) shows sulfide equilibration temperatures ofapproximately 100–135°C, which is also consistent with formation of thesulfides during low-temperature aqueous alteration, and provides anestimate for the minimum parent asteroid alteration temperature of Tarda.
This is consistent with the observation of King et al. (2021) that Tarda has
not been heated. Following the work of Kimura et al. (2008), the low Co
content of Ni-poor Fe,Ni metal also indicates that the sample has not been
noticeably heated. The mean chondrule size of 0.27±0.12 mm is mostsimilar to that of CM chondrites (i.e., 0.27 mm; Rubin and Wasson, 1986).
Fe-Mn systematics of chondrule olivine can help identify genetic
relationships between groups (e.g., Berlin et al., 2011; Schrader et al.,2020). The Fe-Mn compositions of chondrule olivine in Tarda are mostFigure 2. BSE of pyrrhotite-pentlandite intergrowth.
similar to that of CO and CM chondrites, possibly due to similarities in
the formation conditions and/or formation region of their chondrules. While the distinct bulk O-isotope composition (Gattacceca
et al., 2021) and H-C-N compositions (Marrocchi et al., 2021; this study) exclude the possibility that Tarda is a CM chondrite,
Tarda’s chondrules may have formed under similar conditions and from similar precursor materials, potentially in a similar
formation region. In addition to being a fascinating new C2-ung chondrite similar to Tagish Lake, Tarda is a highly hydrated
carbonaceous chondrite that will likely provide a comparison to the hydrated samples returned by Hayabusa2 and OSIRIS-REx.
References
Alexander C.M.O'D. et al., The origin and evolution of chondrites recorded in the elemental and isotopic compositions of theirmacromolecular organic matter, Geochim. Cosmochim. Acta, 71, 4380–4403, 2007.
Alexander C.M.O'D. et al., The provenances of asteroids, and their contributions to the volatile inventories of the terrestrial
planets, Science, 337, 721–723, 2012.
Berlin J. et al., Fe-Mn systematics of type IIA chondrules in unequilibrated CO, CR, and ordinary chondrites, Meteorit. Planet.
Sci., 46, 513–533, 2021.
Bryson J. F. J. et al., Evidence for asteroid scattering and distal Solar System Solids from meteorite paleomagnetism, ApJ, 892,
126, 2020.
Gattacceca J. et al., The Meteoritical Bulletin, No. 109, Meteorit. Planet. Sci., 56, 1626–1630, 2021.
Hiroi T. et al., Meteorite WIS 91600: A new sample related to a D- or T-type asteroid, LPSC, XXXVI, #1564 (abstract), 2005.
Kimura K. et al., Fe-Ni metal in primitive chondrites: Indicators of classification and metamorphic conditions for ordinary andCO chondrites, Meteorit. Planet. Sci., 43, 1161–1177, 2008.
King, A. J. et al., The bulk mineralogy and water contents of the carbonaceous chondrite falls Kolang and Tarda, LPSC, 52,#1909 (abstract), 2021.
Marrocchi Y. et al., The Tarda meteorite: A window into the formation of D-type asteroids, ApJ Letters, 913, L9, 2021.
Nakamura T. et al., MET 00432: Another Tagish Lake-type carbonaceous chondrite from Antarctica, Meteorit. Planet. Sci., 48,#5122 (abstract), 2013.
Rubin A.E. and Wasson J. T., Chondrules in the Murray CM2 meteorite and compositional differences between CM-CO andordinary chondrite chondrules, Geochim. Cosmochim. Acta 50, 307–315, 1986.
Schrader D. L. and Zega T. J., Petrographic and compositional indicators of formation and alteration conditions from LL
chondrite sulfides, Geochim. Cosmochim. Acta, 264, 165–179, 2019.
Schrader D. L. et al., Widespread evidence for high-temperature formation of pentlandite in chondrites, Geochim. Cosmochim.
Acta, 189, 359–376, 2016.
Schrader D. L. et al., Outward migration of chondrule fragments in the Early Solar System: O-isotopic evidence for rocky
material crossing the Jupiter Gap? Geochim. Cosmochim. Acta, 282, 133–155, 2020.
Ushikubo T. and Kimura M., Oxygen-isotope systematics of chondrules and olivine fragments from Tagish Lake C2 chondrite:
Implications of chondrule-forming regions in protoplanetary disk, Geochim. Cosmochim. Acta, 293, 328–343, 2019.
Yamanobe M. et al., Oxygen isotope reservoirs in the outer asteroid belt inferred from oxygen isotope systematics ofchondrule olivines and isolated forsterite and olivine grains in Tagish Lake-type carbonaceous chondrites, WIS 91600 and
MET 00432, Polar Sci., 15, 29–38, 2018.
Acknowledgements: We thank the ASU Center for Meteorite Studies for the samples used in this study, Laurence Garvie forsample preparation, and NASA grant NNX17AE53G (DLS PI, TJZ Co-I) for funding a portion of this research.

Carbonate minerals in the highly-altered A-12248 CM chondrite
Kaitlyn A. McCain1, Ming-Chang Liu1 and Kevin D. McKeegan11
University of California at Los Angeles
The A-12248 meteorite was described in Meteorite Newsletter 26 as a highly-altered CM chondrite with a fracturing index of
A/B, indicating the presence of exterior cracks on the surface (Yamaguchi et al. 2018). To date, no studies of this meteorite
have been published. We received the thin section A-12248 51-3 on loan from NIPR and characterized it using secondary
electron microscopy (SEM). We investigated its petrology using backscattered electron (BSE) and energy-dispersive X-ray
spectroscopy (EDS) imaging. We directed particular attention to carbonate minerals, which precipitated from water during
parent-body aqueous alteration and therefore recorded information about the fluid’s composition and chemistry at the time ofalteration.
A BSE image of the A-12248 51-3 section is shown in Figure 1. Chondrules in A-12248 are nearly completely pseudomorphed,though their outlines are still recognizable. In some cases, the original chondrule petrology can be discerned-a barred olivinechondrule can still be recognized despite complete replacement. No refractory inclusions could be identified. The matrix is
dominated by small TCI (Tochilinite-Cronstedite Intergrowth) clumps. Rare, small Ca-phosphates are found in the matrix.
Anhydrous silicates and FeNi metal are found only in the interior of the least altered chondrules. Magnetite is extremely rare,occurring only once. Though detailed EPMA data are not yet available, this section most closely resembles a CM 2.1 based
upon the rarity of FeNi metal and the near-complete replacement of chondrule silicate (Rubin et al. 2007). However, we notethat other classification criteria suggest a less-altered designation, as discussed below.
Small cracks in contact with the edge of the thin section are partially cemented with Ca and Mg carbonates, consistent withterrestrial alteration during Antarctic exposure (Jull et al. 1988, Tyra et al. 2007). Carbonate within or in contact with theseveins will be excluded from future analyses and all other carbonates must be individually evaluated for a potential terrestrial
component.
Ca-carbonate is the only indigenous carbonate type found in A-12248, in contrast with other CM 2.1 meteorites which often
contain dolomite and other complex carbonates (Rubin et al. 2007). Based upon carbonate mineralogy, the classification CM
2.2 could be applied. Ca-carbonate is petrographically diverse, and is found inside pseudomorphed chondrules, replacing
nearly entire chondrules, and isolated in the matrix. Most grains resemble Type II calcite in petrography, forming large (up to>100 µm) complex aggregates and containing small pores and sulfide inclusions (Tyra et al. 2011). Several inclusion-freegrains isolated in the matrix resembling Type I calcite were found, but overall are much less abundant than those resembling
Type II.
More detailed studies including light microscopy, cathodoluminescence imaging, elemental characterization by SEM-EDS,
and 3 oxygen isotopic analyses using the Cameca ims-1290 at UCLA are planned for carbonates in A-12248. When possible,
carbonates will be measured using an 800 pA Cs+ beam with a precision of ± 0.5‰ (2SD) for both δ17O and δ18O. Smaller
carbonates and anhydrous silicates will be measured using a 40 pA Cs+ beam with a precision of δ17O ± 1.0 ‰ and δ18O ±1.6 ‰ (2SD). The Mn content of each Ca-carbonate will be measured using SEM-EDS and used to assess whether Mn-Cr
dating can be performed.
Further results and details will be presented at the meeting.
References
Yamaguchi, A., Kimura, M., Imae, N., L. Pittarello, V. Debaille, S. Goderis, P. Claeys, Meteorite newsletter: Japanese/Belgiancollection of Antarctic meteorites, Meteorite Newsletter, 26, 1-28, 2018.
A.J.T. Jull, S. Cheng, J.L. Gooding, M.A. Velbel, Rapid growth of magnesium-carbonate weathering products in a stonymeteorite from Antarctica, Science, 242, 417-419, 1988.

M. A. Tyra, J. Farquhar, B. A. Wing, G. K. Benedix, A. J. T. Jull, T. Jackson, M. H. Thiemens, Terrestrial alteration ofcarbonate in a suite of Antarctic CM chondrites: Evidence from oxygen and carbon isotopes. Geochimica et Cosmochimica
Acta, 71(3), 782-795, 2007.
A. Rubin, J. M. Trigo-Rodriguez, H. Huber, J. T. Wasson, Progressive aqueous alteration of CM carbonaceous chondrites,
Geochimica et Cosmochimica Acta, 71(9), 2361-2382, 2007.
M. A. Tyra, J. Farquhar, Y. Guan, and L. A. Leshin. An oxygen isotope dichotomy in CM2 chondritic carbonates—A SIMS
approach, Geochimica et Cosmochimica Acta, 77, 383-395, 2012

Figure 1. Back-scattered electron (BSE) image of A-12248 51-3. The fusion crusted surface is visible at the top and left of the section.

Identifying characteristics of primordial and secondary products in SOM mass distributions
extracted from CI, C2 ungrouped, CR and CM chondrites.
J.Isa1, F.-R. Orthous-Daunay2, V. Vuitton2, L. Flandinet2, L. Bonal2, O. Poch2, and M. Zolensky3
1
Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan2
Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France CS 40700 38058 Grenoble Cedex 9, France
3
NASA Johnson Space Center, Houston, TX 77058, USA
The differences in chemistry, mineralogy, and structure of chondrites demonstrate the variations in time/space of theirformation regions in the solar nebula and the subsequent evolution of their parent body. Naturally, one may expect to findsome variations in the chondritic organics reflecting their different reservoirs in the solar nebula and the secondary
modifications on asteroids [1]. Chondrite soluble organic matter (SOM) is complex, and the aqueous reactions on asteroids arethought to be where it was synthesized [2]. Our previous study of Tagish Lake (C2 ungrouped) showed that the primordial
SOM could be distinguished from the parent body's secondary alteration through mass distribution. Also, we concluded thatthe complex nature of the primordial SOM was established before severe alteration on the asteroid and later became simplified
on the asteroid [3]. However, it remains unclear if this conclusion can be generalized and applied to other chondrite groups.
This study will show the variations and common SOM features among different chondrite groups and petrologic types byusing the model from our previous study.
Sample and Method: Tarda (C2 ungrouped), Orgueil (CI), Murchison (CM2), EET 96029 (CM2), GRO 95577 (CR1), EET
92159 (CR2), GRA 06100 (CR2), GRO 03116 (CR2), and MIL 090657 (CR2) meteorite SOM, as well as chondrite organic
simulant SOM, were used. We analyzed the methanol/toluene extract with the high-resolution Orbitrap mass spectrometer
located at the Institut de Planétologie et d'Astrophysique de Grenoble (IPAG). We directly injected and ionized the SOM andits solvent by using an Electrospray Ionization (ESI) source. After spectra acquisition, post-processing data analysis tools with
the name Attributor [4], which were developed in-house, were employed.
Preliminary Results: Tarda and the other type 2 chondrites' SOM mass distribution were well fit by using the modelinterpreted as the primordial SOM distribution in Tagish Lake. This match among the distribution patterns from different
chondrite types implies the presence of a common organic reservoir or a common mechanism for SOM formation. The model
fits better to Tarda SOM distribution than Tagish Lake ones; that implies that Tarda was less altered in the parent body thanTagish Lake, consistent with their minerlogies. Orgueil and GRO 95577 (CR1) share the common shape in their mass
distribution of a few alkyl homologous series, and these unique features are apparent only in type 1 chondrites' extracts (Figure1). In contrast to the mass distribution, SOM's elemental abundance was distinct among the different chondrite groups. In thepresentation, we will discuss in detail the common features among the chondrite groups through the alteration on individual
parent bodies based on the mass distribution and chemical formulae of detected ions.

Figure 1: Selected CH2 family intensity pattern from A: Orgueil, B GRO 95577 (CR1) and C Tarda (C2) extracts. Multimodal peaks
appeared in the type-1. The red line is the best fit to the SZ model interpreted as the primordial SOM distribution in Tagish Lake.

References: [1] Naraoka and Hashiguchi (2019) Geochemical Journal, 53, 33-40, [2] Cronin and Chang, (1993) The
Chemistry of Life’s Origins pp 209-258 [3] Isa et al. (2021) The Astrophysical Journal Letters (accepted), [4] OrthousDaunay, F. R. et al. (2019) Geochemical Journal, 53(1), 21-32.

High-pressure minerals in CB carbonaceous chondrites
Masaaki Miyahara1, Eiji Ohtani2, Akira Yamaguchi3, Naotaka Tomioka4
1
Hiroshima University, 2Tohoku University, 3NIPR, 4JAMSTEC

It is widely accepted that carbonaceous chondrites are less shocked compared to ordinary chondrites.
A high-pressure mineral, which is one of stark evidence for shock metamorphism, is ubiquitously foundin ordinary chondrites (Miyahara et al. 2020, 2021 and references therein). By contrast, based on previous
studies, only a few carbonaceous chondrites include a high-pressure mineral (Tomioka and Miyahara
2017 and references therein). Among carbonaceous chondrites, CB carbonaceous chondrite is a uniquegroup because it consists mainly of metal and chondrule. Although the origin of CB carbonaceouschondrite has been under debate, some previous studies propose that CB carbonaceous chondrite may beformed through a planetesimal collision between carbonaceous chondrite and iron meteorite parentbodies (Weisberg and Kimura, 2010). Most CB carbonaceous chondrites show evidence for melting,probably induced by shock metamorphism. In this study, we investigate a high-pressure mineral in four
CB carbonaceous chondrites: Gujba, Bencubbin, NWA 1814, and NWA 4025 to clarify its history ofshock metamorphism and origin using FEG-SEM, EMPA, and laser Raman spectroscope.
Gujba, Bencubbin, NWA 1814, and NWA 4025 consist of a chondrule, metal spherule, and matrix.
The chondrule and metal spherule are deformed, and their sizes are 1–5 mm across. The chondrules haveirregular fractures and consist mainly of olivine, low-Ca pyroxene, high-Ca pyroxene, and glass. The
metal spherule consists of kamacite-taenite. Some metal spherules include a small amount of iron-sulfide
patch. The kamacite-taenite and iron-sulfide have a eutectic texture in the patch. Other metal spherules
include fragmented chondrules. The matrix consists of fragmented chondrules, and their outlines arerounded. The interstices of the fragmented chondrules are filled with fine-grained olivine and pyroxene,
glass (or poorly crystallized material), and metallic iron.
The high-pressure polymorphs of olivine, pyroxene, and plagioclase are found mainly in the matrix ofGujba, Bencubbin, NWA 1814, and NWA 4025. Gujba includes wadsleyite, ringwoodite, akimotoite,
majorite, Ca-bearing majorite, lingunite, and Na-pyroxene as a high-pressure mineral. Pyroxene-glass
also occurs in the matrix, which may be vitrified bridgmanite. Also, Weisberg and Kimura (2010) andGarvie et al. (2014) found majorite-pyrope solid-solution, coesite, and diamond in Gujba. Considering theassemblage of high-pressure minerals, the shock pressure recorded in Gujba would be at 22–23 GPa.
Bencubbin includes majorite, Ca-bearing majorite, and pyroxene-glass. The estimated shock pressure in
Bencubbin is 15–22 GPa. NWA 1814 includes Na-pyroxene, coesite, and pyroxene-glass. The estimatedshock pressure is 22–23 GPa. NWA 4025 includes majorite and pyroxene-glass and the estimated shockpressure is 22–23 GPa.
Our systematic investigations of Gujba, Bencubbin, NWA 1814, and NWA 4025 indicate that highpressure minerals occur ubiquitously in the matrices of CB carbonaceous chondrites. The chondrules are
deformed and fractured. The metal spherules are also deformed and include the fragmented chondrules.
The matrices of CB carbonaceous chondrites consist of quenched melts and fragmented chondrules. CB
carbonaceous chondrites likely experienced heavy shock metamorphism after metal spherules andchondrules were accumulated on the parent body. The estimated shock pressures based on high-pressureminerals are similar to each other. CB carbonaceous chondrites may be disrupted from the parent bodysimultaneously.
References
Garvie L.A.J., Németh P., & Buseck P.R. (2014). Transformation of graphite to diamond via a topotactic mechanism. Am Min
99:531–538.
Miyahara M., Yamaguchi A., Saitoh M., Fukimoto K., Sakai T., Ohfuji H., Tomioka N., Kodama Y., & Ohtani E. (2020).
Systematic investigations of high-pressure polymorphs in shocked ordinary chondrites. Meteorit Planet Sci 55:2619–2651.
Miyahara M., Tomioka N., & Bindi L. (2021) Natural and experimental high-pressure, shock-produced terrestrial andextraterrestrial materials. Progress in Earth and Planetary Science, in press.
Tomioka N. & Miyahara M. (2017). High‐pressure minerals in shocked meteorites. Meteorit Planet Sci 52:2017–2039.
Weisberg M.K. & Kimura M. (2010). Petrology and Raman spectroscopy of high pressure phases in the Gujba CB chondriteand the shock history of the CB parent body. Meteorit Planet Sci 45:873–884.

Infrared spectroscopy of astromaterials with nanoscale resolution
Mehmet Yesiltas1, Timothy D. Glotch2, Bogdan Sava3
Faculty of Aeronautics and Space Sciences, Kirklareli University, Kirklareli, Turkey
2
Department of Geosciences, Stony Brook University, Stony Brook, New York, USA
3
Neaspec GmbH, D-85540 Haar, Munich, Germany

1

Introduction: Astromaterials are invaluable samples for understanding the formation of our solar system. Investigation of
returned asteroid particles, micrometeorites, and meteorites significantly contributes to our understanding of the early solar
system. Carbonaceous chondrites, for instance, are some of the most primitive extraterrestrial samples, and they retain recordsof their origin, formation, evolution and post-accretionary processes. Their heterogeneous chemical composition includes awide range of organic compounds as well as minerals. Organic molecules are typically sub-micron in size [1,2]. Organic
nanoglobules are even smaller (50–500 nm). [3,4]. As such, novel analytical techniques with nanoscale spatial resolution are
required to detect and characterize such organic matter within meteorites. It is also important to preserve the petrographic
context and not alter the organic matter during the investigation. Conventional Fourier transform infrared (FTIR) spectroscopy
is a non-destructive analytical technique; however, its spatial resolution is not high enough to detect and identify spectral
signatures of organic molecules that are smaller than a micrometer. In contrast, nanoscale near-field infrared (nano-FTIR)
spectroscopy can non-destructively characterize organic matter and mineral phases in extraterrestrial samples with nanoscalespatial resolution (e.g., 5-7). It is not affected by the optical diffraction limit, independent of the wavelength, preserves thecontext since it does not require powdered or chemically processed samples. Therefore, nano-FTIR spectroscopy is a powerful
analytical tool for the investigation of constituents of extraterrestrial materials. In this work, we report nano-FTIR spectral
results of organic matter identified in carbonaceous chondrites.
Technique: This work considers several carbonaceous chondrites that were prepared in the form of polished sections. We
conducted our nano-FTIR spectroscopic experiments using a commercial s-SNOM nano-FTIR imaging and spectroscopy
system (neaspec GmbH) equipped with mid-infrared broadband lasers. Spectra were collected within the 2000–650 cm-1
spectral range with ~20 nm spatial resolution. AFM scans were collected using a Pt coated neaspec cantilever tip that maps thesurface topography. Sample drift was monitored constantly by checking the reference points on each sample.
Results:
Figure 1. Identification of carbonyls. A and B
respectively present mechanical and amplitude
images of a region in DOM 08006 (CM3.0). NanoFTIR spectra of the points indicated by diamonds in
A and B are shown in C. The infrared band at 1730
cm-1 is due to carbonyls, which is absent in the pink
spectrum that was collected within the matrix.
Figure 2. Identification ofroughly spherical carbonyl
nanoglobules in DOM
08006.

References[1] Busemann et al. 2006; Science, 312,727-730. [2] Remusat et al. 2010, The Astrophysical Journal 713,1048. [3] NakamuraMessenger, K. et al. 2006, Science, 314,1439-1442. [4] De Gregorio, B. T. et al. 2013, Meteoritics & Planetary Science,
48,904-928. [5] Kebukawa et al. 2019; PNAS, 116, 753-758. [6] Yesiltas et al. 2020, Meteoritics & Planetary Science, 55,
2404-2421. [7] Yesiltas et al. 2021, Scientific Reports, 11, 11656.

Formation of spherical iron oxide minerals by oxidative hydrothermal alteration frommetallic spherules: Implications for hematite spherules and surface conditions of Mars

Huimin Shao1, Hiroshi Isobe1*, Ginga Kitahara1, and Akira Yoshiasa1
1

Department of Earth and Environmental Sciences, Faculty of Advanced Science and Technology,
Kumamoto University, Kumamoto, 860-8555, Japan.

The formation mechanism of hematite spherules on Mars was widely discussed by researchers (e.g.
Bowen et al., 2008; Fan et al., 2010). The discussion about the formation history of the hematite spherules
could provide the Martian surface condition. In this study, oxidative hydrothermal alteration experimentson reproduced I-type (iron type) cosmic spherules were carried out to investigate the formation historyof hematite spherules on Mars.
The starting material used in this study was reproduced I-type cosmic spherules formed by hightemperature heating and quenching experiments from Canyon Diablo iron meteorite (Shao et al., 2020)in a reduced atmosphere controlled by Ar (98%) and H2 (2%) gas flow to protect from oxidation. The
starting material shows a homogeneous composition with approximately 7 wt% Ni and 93 wt% Fe in themetallic phase. Detailed conditions of hydrothermal alteration experiments are shown in Table 1.
Table 1. Experimental conditions

Based on the observation of all the run products, we suggestthat the Martian hematite spherules could be formed frommetallic spherules produced in the ablation of iron meteorites
during Martian atmospheric entry. The area with high-density
Martian hematite spherules may be derived from an explosion
5
150
10
7
√
and ablation events of large iron meteorites at a low altitude.
6
150
10
4
×
The reproduced hematite on artificial I-type cosmic spherules
7
150
30
7
√
formed in this study contains Ni content from 0.52 to 4.77
8
150
30
7
×
wt%. Thus, we suggest that the hematite spherules which
9
150
100
7
×
were oxidized from metallic spherules originated from iron
10
150
100
4
×
meteorites or I-type cosmic spherules typically have Ni
11
200
10
7
×
12
200
10
4
×
content with a few wt.%. However, hematite spherules
13
200
30
7
√
precipitated in the aqueous process only contain Ni less than
14
200
30
7
×
tens of ppm (Bowen et al., 2008). If an obvious nickel content
15
200
100
7
×
could be detected in Martian hematite spherules from future
16
200
100
4
×
Martian missions, the Martian hematite spherules may beformed by oxidation of metallic spherules rather than precipitation from a fluid. Furthermore, it could bealso suggested that the Martian hematite spherules deposit is not a suitable place to find the ancient river,
not as researchers thought previously. In this study, we propose that the precursor of Martian hematite
spherules should be metallic spherules derived from iron meteorites.
References
Bowen, B.B., Benison, K.C., Oboh-Ikuenobe, F.E., Story, S., Mormile, M.R., 2008. Active hematite
Exp.
1
2
3
4

T (℃)
100
100
100
100

Dur (days)
10
10
30
30

pH
7
4
7
4

CO2
×
×
×
×

concretion formation in modern acid saline lake sediments, Lake Brown, Western Australia. Earth andPlanetary Science Letters 268, 52-63.
Fan, C., Xie, H., Schulze-Makuch, D., Ackley, S., 2010. A formation mechanism for hematite-rich
spherules on Mars. Planetary and Space Science 58, 401-410.
Shao, H., Isobe, H., Miao, B., 2020. Reproduction of I-type cosmic spherules and characterization in an
Fe-Ni-O system. Meteorit. Planet. Sci.

Comprehensive study of shock metamorphism and 40Ar/39Ar ages in ordinary chondrites
Atsushi Takenouchi1, Hirochika Sumino2 and Akira Yamaguchi2
1
The Kyoto University Museum, Kyoto University
2
Graduate School of Arts and Science, The University of Tokyo
3
National Institute of Polar Research (NIPR)
Introduction
Ordinary chondrites have experienced shock metamorphism in various degrees. For example, L chondrites commonly
contain high-pressure phases, indicating that those meteorites have metamorphosed under high-pressure and high-temperature(e.g., Tomioka and Miyahara 2017). Stöffler et al. (1991, 2018) classified such shock metamorphic degrees based on shocktextures from unshocked (1) to highly shocked (6), and this classification is widely used to represent shock degrees efficiently.
On the other hand, 40Ar/39Ar ages (hereafter Ar/Ar ages) have been measured to investigate impact histories in each meteorite
group (e.g., Bogard 2011; Swindle et al. 2014). While several studies have discussed the degrees of impact events and theirtiming (e.g., Friedrich et al. 2014; Rubin 2004), the number of such research is still limited. Moreover, in general, observationof shock textures and their chronology were performed separately using different specimens. A comprehensive study
investigating shock metamorphism and impact ages of many meteorites is needed to reveal impact histories during the solar
system formation. Therefore, we have been analyzing both shock metamorphism and Ar/Ar ages of ordinary chondrites using
identical specimens. Here, we report our results so far and discuss the impact histories of ordinary chondrites.
Samples and Methods
We prepared twenty-six H chondrites, three L chondrites, and three LL chondrites (Table 1). Part of them was boughtfrom meteorites dealers, and the others were provided by the University of Tokyo and NIPR. We observed polished thinsections of each meteorite by an optical microscope and FE-SEM (JEOL JMS-7100F at NIPR). Chips of each meteorite were
irradiated by neutrons at Institute for Integrated Radiation and Nuclear Science, Kyoto University. Ar/Ar analyses were
performed using modified VG-3600 at the University of Tokyo. Detailed data reduction is described in Takenouchi et al.
(2020).
Results
We summarize our observation results so far and obtained Ar/Ar ages in Table 1. Some Ar/Ar ages were previously
reported in Takenouchi et al. (2020), and data from Swindle et al. (2014) are also shown. In this study, seven Ar/Ar ages are
newly reported. Ar/Ar age spectrum of Mills is shown in Fig. 1 as an example. Shock stages were determined based on theclassification suggested by Stöffler et al. (2018). Fig. 2 represents shock stages versus Ar/Ar ages as per Table 1. Meteorites
with younger Ar/Ar ages (<4000 Ma) show higher shock stages (≥3), while shock stages of meteorites with older ages (>4000
Ma) are variable. Only two out of twenty-six H chondrites contain high-pressure phases indicating that high-pressure phases
are less common in H chondrites than in L chondrites.
Discussion and Conclusion
In general, moderate to strong shock metamorphism is needed to completely reset Ar/Ar ages (e.g., Bogard et al.
1995), and unshocked meteorites should retain their formation ages. Therefore, the trend in Fig. 2 appears natural because
strongly shocked meteorites have reset Ar/Ar ages and unshocked meteorites exhibit older ages. However, only weakly
shocked meteorites such as Ochansk and Mills show relatively young ages around 4200 Ma (Fig. 2). Such Ar/Ar age is too
young to represent the chondrites’ formation age and should represent an impact age. Furthermore, those meteorites commonly
show healed cracks, which formed during heating after the crack formation. Therefore, these meteorites may have experienced
post-shock annealing to erase significant shock metamorphic textures similar to meteorites reported previously (Rubin 2004).
Rubin et al. (2001) suggested that Portales Valley, whose Ar/Ar age is 4480±40 Ma, may also be annealed by shock event
based on its textures. Therefore, these results indicate that impact events until ~4200 Ma were sometimes accompanied bystrong post-shock annealing. On the other hand, meteorites with low shock stage and young Ar/Ar ages are not found so far,which possibly indicates that recent impact events (after at least 4200 Ma) rarely induced post-shock temperature strong
enough to erase shock metamorphic textures. Such a difference in post shock annealing can be attributable to changes in
impact conditions at around 4200 Ma. To ensure the trend of shock metamorphism and reveal impact histories of meteorites,
further analyses with increasing samples is required.
References
Bogard D. D., Garrison D. H., Norman M., Scott E. R. D., and Keil K. 1995. 39Ar40Ar age and petrology of Chico: Largescale impact melting on the L chondrite parent body. Geochimica et Cosmochimica Acta 59:1383–1399.

Bogard D. D. 2011. K-Ar ages of meteorites: Clues to parent-body thermal histories. Chemie der Erde 71:207–226.
http://dx.doi.org/10.1016/j.chemer.2011.03.001.
Friedrich J. M., Rubin A. E., Beard S. P., Swindle T. D., Isachsen C. E., Rivers M. L., and Macke R. J. 2014. Ancient porosity
preserved in ordinary chondrites: Examining shock and compaction on young asteroids. Meteoritics and Planetary
Science 49:1214–1231.
Rubin A. E., Ulff-Moller F., Wasson J. T., and Carlson W. D. 2001. The Portales Valley meteorite breccia: Evidence for
impact-induced melting metamorphism of an ordinary chondrite. Geochimica et Cosmochimica Acta 65:323–342.
Rubin A. E. 2004. Postshock annealing and postannealing shock in equilibrated ordinary chondrites : Implications for thethermal and shock histories of chondritic asteroids. 68:673–689.
Stöffler D., Keil K., and Edward R.D S. 1991. Shock metamorphism of ordinary chondrites. Geochimica et Cosmochimica
Acta 55:3845–3867.
Stöffler D., Hamann C., and Metzler K. 2018. Shock metamorphism of planetary silicate rocks and sediments: Proposal for an
updated classification system. Meteoritics and Planetary Science 53:5–49.
Swindle T. D., Kring D. A., and Weirich J. R. 2014. 40Ar/39Ar ages of impacts involving ordinary chondrite meteorites. In
Advances in 40Ar/39Ar Dating: from Archaeology to Planetary Sciences. pp. 333–347.
Takenouchi A., Sumino H., and Yamaguchi A. 2020. Shock metamorphism and Ar-Ar ages of ordinary chondrites. 11th Polar
Science symposium OPp1.
Tomioka N., and Miyahara M. 2017. High-pressure minerals in shocked meteorites. Meteoritics and Planetary Science
52:2017–2039.

Fig. 1 Ar/Ar age spectrum of Mills showing aplateau age of 4206±97 Ma.

Fig. 2 Shock stages and Ar/Ar ages of meteorites
studied (Blue: H chondrites, Orange: L chondrites).
Error bars (2σ) are shown, and only younger ages inTable 1 are plotted with arrows as Ar/Ar ages in thisgraph. The impact event of L chondrites at 0.5 Ga (e.g.,
Swindle et al. 2014) is also shown.

Table 1 Thermal metamorphic types, shock stages and Ar/Ar ages of meteorites used in this study. Errors in Ar/Ar ages are 2σ.
Shock
Shock
Name
TYPE
Age (Ma)
Name
TYPE
Age (Ma)
Stage
Stage
Tulia(a)H3-4
3<2000-4000
ChergachH5
4
Y-75028
H3-6
3
Mills
H6
2
4206±97
Y-791428
H3.7
1
Ozona
H6
2
<4500**
Y-790460
H3.7
34520±110
Portales Valley
H61
4480±40***
Ochansk
H4
2<4200
A 10174H6
3
Salaices
H43<4400**A 12363H6
2
Wellman-c
H44<3800**Y 981909
H6
5+
Hassayampa
H434520±110
Y-791775
H6-melt rock
2
<4300
Kesen
H4
3
Y-75100
H6
5+<4490±140*<300-400
Jilin
H53
Tassédet 004
H5-melt rock
4
<3800
**
Nuevo Mercurio
H514481±92
Seagraves (c)L65+<1600-2900**
Gao-Guenie
H53
303±110*Y 000775
L6
5+
Nadiabondi
H5
3
Y-790521
L-melt rock3
Plainview (1917)
H544460±110
Y-790144
LL7
3
Forest City
H5
3
Y-790519
LL-melt rock2
Y-794046H5?
3
3790±80*
Y-790964
LL-melt rock3
*Swindle et al. (2014) and references therein **Takenouchi et al. (2020) after further data reduction +contains high-pressure phases

The effect of fluid mobilization on the budget and distribution of rare earth elements in Antarctic
H chondrites
Ryoga Maeda1, 2, Steven Goderis1, Thibaut Van Acker3, Frank Vanhaecke3,
Akira Yamaguchi4, Vinciane Debaille2 and Phillippe Claeys1
1
Analytical-, Environmental-, and Geo-Chemistry, Vrije Universiteit Brussel, Belgium
2
Laboratoire G-Time, Université libre de Bruxelles, Belgium
3
Atomic & Mass Spectrometry Research Unit, Department of Chemistry, Ghent University, Belgium
4
National Institute of Polar Research, Japan
Introduction
Rare earth elements (REEs) are universally used for understanding planetary processes such as silicate differentiation
and are often considered to be relatively immobile. Despite this overall immobility, previous studies on the weathering effects
on REEs have demonstrated that terrestrial weathering including Antarctic alteration can modify original REE compositions
both in terms of absolute concentrations and isotopic ratios [e.g., 1]. In addition, Maeda et al. [2] put forward that Antarctic
alteration may be significantly more complex than previously acknowledged. The detailed mechanisms of the alteration,
however, remain poorly understood. In this study, H chondrites (HCs) with various degrees of weathering are investigated toreveal the underlying mechanisms through the use of several types of in-situ measurements.
Experimental
Polished thick sections (PTSs) were prepared for ten Antarctic HCs, two HCs collected from hot deserts, and four fallHCs provided by the Royal Belgian Institute of Natural Sciences (RBINS), Belgium, and the National Institue of Polar
Research (NIPR), Japan. Firstly, these PTSs were analyzed using micro-X-ray fluorescence spectrometry (μXRF) at the Vrije
Universiteit Brussel (VUB), Belgium, to obtain maps showing the distributions of major elements. Secondly, back-scatteredelectrons (BSE) images of each sample were acquired using a field emission-scanning electron microscope (FE-SEM)
equipped with an energy-dispersive spectrometer (EDS) at NIPR. Once the constituent minerals in the samples were identified
based on the elemental maps and BSE images obtained, an electron probe micro analyzer (EPMA) at NIPR was used for thedetermination of major elemental abundances in each constituent mineral. After the EPMA analysis, trace element mapping
was conducted for selected samples using laser ablation-inductively coupled plasma-time of flight-mass spectrometry (LAICP-TOF-MS) at Ghent University, Belgium. Finally, the abundances of REEs and other trace elements of choice were
determined for constituent minerals and cracks using single point drilling for the minerals and line scans for the cracks by LAICP-MS at NIPR.
Results and Discussion
According to the result of the trace element mapping using LA-ICP-TOF-MS, a considerable amount of REEs resides
in the cracks within Asuka (A) 09618 (H5), which is severely weathered and categorized to C following the weathering index(WI), as shown in Fig. 1. Other highly weathered samples, e.g., A 09516 (H6; WI: C) and Sahara 97035 (H5; WI: W2), also
show such a deposition of Ce in cracks, but this is not observed for the other REEs. Based on the REE abundances in cracks asdetermined using LA-ICP-MS line scanning, some cracks display elevated REE abundances relative to the bulk rock (Fig. 2 as
an example). These REE-enriched cracks usually also contain high Th and U abundances. Considering the P2O5/SiO2 in cracks(Fig. 2), most of the high REE-cracks must be explained by a nugget effect of Ca-phosphates, as crack-1 and crack-2 showhigh REE, Th, and U abundances with a high P2O5/SiO2, while crack-4 displays low abundances in these elements

Fig. 1. Elemental maps of Asuka 09618 (H5, WI: C) obtained using LA-ICP-TOF-MS: a combined RGB map (Red=Ca;
Green=Si; Blue=Fe; mer: merrillite; apa: apatite) at left; a Ce map at right.

accompanied by a low P2O5/SiO2 in Fig. 2.
However, crack-3 displays REE, Th, and U
Asuka 09618 (H5)abundances as high as those in crack-1 andcrack-2 with a small negative Ce anomaly,
even though the P2O5/SiO2 is as low as thatobserved for crack-4 (Fig. 2). This cannot
be explained by the nugget effect of Caphosphates. Thus, cracks appear toaccumulate unbonded REEs locally as thetrace element maps suggest suchdepositions. Probably, Th and U candeposit in these cracks as well. This isconsistentwithchemicalleaching
experiments [e.g., 5], in which REEs, Th,
and U have been expected to be depositedin cracks and grain boundaries. The traceelement mapping using LA-ICP-TOF-MS
Fig. 2. CI-normalized REE, Th, and U abundances and ratios of Na2O to SiO2 andreported on here represents the first P2O5 to SiO2 in cracks for Asuka 09618 (H5, WI: C). Bulk rock values are from [2].
instance in which such depositions are The Na2O/SiO2 and P2O5/SiO2 for bulk rock are calculated from HC mean values in[3]. CI values are from [4].
visually confirmed.
Based on the LA-ICP-MS line scans, cracks in all of the weathered samples categorized as B/C, C, W1, and W2 inthis study display positive Ce anomalies similar to that observed for crack-4 in A 09618 (Fig. 2). A crack having unbonded
REEs with a small negative Ce anomaly such as crack-3 in A 09618 is also found in Sahara 97035. The crack also desplays no
feature of high P and Ca abundances. Because the positive Ce anomalies and unbonded REE depositions occur in all weathered
samples, the pattern observed likely results from terrestrial weathering. According to Mittlefehldt and Lindstrom [6], meltingof ice can trigger sample alteration following chemical leaching as demonstrated by the loss of Ca-phosphates in eucrites from
Antarctic samples, in line with our observations for cracks in chondrites. Rain or humidity is known to trigger a similar
mechanism in hot deserts. During the residence of meteorites in Antarctica or hot deserts, fluids such as melting ice or rainpass through the interior of a meteorite following any physical cracks or grain boundaries. During the passing of such fluids, afraction of the Ca-phosphates is dissolved or partially dissolved in this fluid. In the case that the Ca-phosphates are completely
dissolved, P and Ca completely pass through the meteorite, while REEs largely remain in cracks because REEs are
significantly more immobile than P and Ca [7, 8]. At a later stage of this alteration sequence, only Ce remains in the cracks,
while the other REEs are removed because Ce is considerably more immobile than the other REEs as a result of oxidationfrom Ce3+ to Ce4+ [6]. This is supported by the observation that unbonded REEs deposited in cracks show a negative Ceanomaly. In the case that Ca-phosphates were partially dissolved, it is assumed that only trace elements such as REEs are
extracted from Ca-phosphates as a result of an interruption in the ionic bonding between cations, particularly impurity cations,and (PO4)2- in the Ca-phosphates [2]. Then, in a similar manner, the REEs are mobilized from the cracks while only Ceremains there in the later stages. In hot deserts, such a chemical leaching may occur with secondary carbonates as well as Caphosphates. Both alteration scenarios can explain a deposition of unbonded REEs with a small negative Ce anomaly and adepleted REE pattern with a positive Ce anomaly in cracks. The depositions of unbonded REE likely represent a transitional
stage of the alteration and the positive Ce anomalies represent a later stage, and as such, positive Ce anomalies may be acommon feature in cracks. This is indeed consistent with the observation that only two cracks show a deposition of unbonded
REE, while ~20 out of the 51 cracks studied here exhibit a positive Ce anomaly. Therefore, it seems that the depositions ofunbonded REE and positive Ce anomalies in cracks are both caused by terrestrial alteration following chemical leaching.
However, because bulk elemental abundances including REEs in these samples except for A 09516 are in good agreement with
HC mean values [2], this alteration occurs locally only and the effect on the bulk composition is generally limited.
References[1] Pourkhorsandi et al. (2021) Chem. Geol. 562, 120056. [2] Maeda et al. (2021) GCA 305, 106-129. [3] Jarosewich (1990)
Meteoritics 25 (4), 323-337. [4] Anders and Grevesse (1989) GCA 53, 197-214. [5] Ebihara and Honda (1984) Meteoritics 19(2), 69-77. [6] Mittlefehldt and Lindstrom (1991) GCA 55, 77-87. [7] Middelburg et al. (1988) Chem. Geol. 68, 253-273. [8]Bland et al. (2006) In Meteorites and the Early Solar System II (eds. Lauretta D. S. and McSween Jr. H. Y.), pp. 853–867.

Thermal and shock history of diogenites based on the occurrence of silica minerals
Rei Kanemaru1, Akira Yamaguchi2, 3, Naoya Imae2,3 and Atsushi Takenouchi4
Institute of Space and Astronautical Science, 2National Institute of Polar Research,
3
Graduate University of Advanced Studies, SOKENDAI, 4Kyoto University

1

Introduction
Diogenites are a group of HED (howardites, eucrites, diogenites) meteorites [1, 2]. The HED meteorites are considered
to have originated from the lower crustal material of asteroid Vesta (e.g., [3]). The petrographic study of HED meteorites provides
us the information about thermal and shock history on the HED parent body. Recently, silica minerals in eucrites have been used
as an indicator of the thermal and shock history of eucrites (e.g., [4, 5]). However, the occurrence and combination of silica
minerals in diogenites have not been well-studied (e.g., [6]). In this study, we investigated the occurrences and compositions ofsilica minerals in diogenites to better understand the origin. Moreover, on the basis of the observations, we aim to understandthe shock and thermal history of diogenites.
Sample and methods
In this study, we studied nine Antarctic and non-Antarctic diogenites. We studied three types of diogenite including
unbrecciated diogenites (NWA 7831, NWA 8043, NWA8107), brecciated diogenites (NWA 4965, NWA 8703, Bilanga), andrecrystallized diogenites (Tatahouine, Y 002875, Y-74013). These diogenites were observed by an optical microscope and afield emission scanning electron microscope (FE-SEM: JEOL JSM-7100) with an energy dispersive spectrometer (EDS) (Oxford
AZtec Energy) and a cathodoluminescence system (GATAN ChromaCL) at the National Institute of Polar Research, Tokyo(NIPR). Silica polymorphs were identified by a Raman spectrometer (Renishow) at NIPR.
Results
We found silica minerals in all studied diogenites (<~1 vol.%). We identified (monoclinic: MC-, pseudo orthorhombic:PO-) tridymite, cristobalite, and quartz in diogenites (Table 1, Fig. 1). These silica minerals mainly occur as short-veins or tinyrounded grains. The combinations of silica minerals in each diogenite were closely related to the types of diogenites. The
unbrecciated diogenites (e.g., NWA 7831) show a sharp optical extinction (<~2º) under the optical microscope. These diogenites
contain MC tridymite coexisted with a small amount of cristobalite. The brecciated diogenites show undulatory extinction. NWA
8703 shows a weak undulatory extinction (~5º), containing MC tridymite, PO tridymite, and quartz. Bilanga and NWA 4965
show a strong undulatory extinction (~15º), containing only quartz. The recrystallized diogenites show a sharp optical extinction(<~2º). Y 002875 contains MC tridymite and PO tridymite. Tatahouine and Y-74013,1 contain MC tridymite, PO tridymite, andcristobalite.
Discussion
Cristobalite is considered to be a primary silica phase crystallized from diogenitic magma. The cristobalite underwent
a phase transition to tridymite during the cooling process. The presence of cristobalite indicates that the diogenites areunequibrium state at the subsolidus temperature. It is suggested that some diogenites experience a rapid cooling processcomparable to basaltic eucrites [4]. The modal abundances of quartz in diogenites tend to increase to undulatory extinction angle
ranges ( ~5º to ~15º). In eucrites, it is observed that tridymite transforms silica glass and quartz by shock metamorphism (shockpressure > ~10 GPa) [5]. Thus, quartz in shocked diogenites also transforms from tridymite or silica glass. On the other hand,
we could not find quartz in the recrystallized diogenites. The absence of quartz could be due to the difference in pressure andthermal conditions at the shock event. We suggest that recrystallized diogenites experienced strong thermal metamorphism atleast stable condition of quartz (>~870 ℃) during shock metamorphism. PO tridymite is observed in brecciated diogenites andrecrystallized diogenites. The relationship between PO tridymite and shocked diogenites could be explained by shock pressure
and thermal metamorphism. However, the phase transition process of PO tridymite is complex, and we could not constrain thetemperature and pressure conditions.
In summary, unbrecciated diogenites retain the primary silica minerals of cristobalite and MC tridymite. On the other
hand, brecciated diogenites contain quartz and PO tridymite. It was suggested that these silica minerals were formed by shock
metamorphism. In addition, the amount of quartz increased with the increase of shock metamorphism. Recrystallized diogenites
contain MC tridymite, PO tridymite, and cristobalite. The absence of quartz indicates that the recrystallized diogenite
experienced stronger thermal metamorphism than brecciated diogenites.

Table 1. Silica minerals in studied diogenites
TextureSamples

Silica minerals

Undulatory extinction Shock vein

Crs

PO Trd MC Trd

Qtz

NWA 7831

unbrecciated<2º (Sharp)

-

Yes

Yes

NWA 8043

unbrecciated<2º (Sharp)

-

Yes

Yes

NWA 8107

unbrecciated<2º (Sharp)-

NWA 8703

breccia~5º (Weak)-NWA 4965

breccia~15º (Strong)-Yes

Bilanga

breccia~15º (Strong)

Yes?

Yes

Tatahouine Recrystallized<2º (Sharp)-

Y-002875

Recrystallized<2º (Sharp)-

Y-74013,1

Recrystallized<2º (Sharp)

-

Yes
Yes

Yes
Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Crs: Cristobalite; PO Trd: Pseudo orthorhombic tridymite; MC Trd: Monoclinic tridymite; Qtz: Quartz.

Fig. 1. BSE and chromaCL images of silica minerals in diogenites. MC tridymite shows a bright aqua-blue CL emission. Cristobalite andPO tridymite show a dark blue CL emission. Quartz shows a dark purple CL emission.

References[1] Takeda, H., Mori, H., Prinz, J. s., Harlow, G. E., Ishii, T., 1983. Mineralogical comparison of Antarctic and non-Antarctic
HED howardites–eucrites–diogenites. Proc. Symp. Antarct. Meteorites. 8, 114-116.
[2] Yamaguchi, A., Barrat. J. A., Greenwood, R., 2017. Achondrites. Springer.
[3] Binzel, R.P., Xu, S., 1993. Chips off asteroid 4 Vesta: evidence for the parent body of basaltic achondrite meteorites.
Science. 260, 186–191.
[4] Ono, H., 2020. Crustal evolution of asteroid Vesta as inferred from silica polymorphs in eucrites. Doctoral Dissertation,
Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo.
[5] Kanemaru, R., Yamaguchi, A., Imae, N., Takenouchi. A., Nishido, H., 2021. Shock effects in silica minerals in eucrites.
JPGU 2021, PPS07-14.
[6] Benzerara, K., Guyot, F., Barrat, J. A., Gillet, P., Lesourd, M., 2002. Cristobalite inclusions in the Tatahouine achondrite:
Implications for shock conditions. Amer. Miner., 87, 1250-1256.

Determination of the real size distribution of chondrules based on
the measured size distributions in thin sections
József Vanyó1, Arnold Gucsik1, 2, Árpád Csámer2, Péter Futó2, and János Sztakovics1
1
Eszterházy Károly Catholic University, Faculty of Natural Sciences, Institute of Chemistry and Physics,
Department of Physics, H-3300, Eger, Leányka utca 6-8
2
University of Debrecen, Cosmochemistry Research Group, Department of Mineralogy and Geology, Institute for Earth
Sciences, University of Debrecen, H-4032, Egyetem tér 1 Debrecen, Hungary
The conditions under which chondrules are formed can be inferred mainly from their physical, chemical and geometricproperties. So far, chemical properties have been studied in numerous studies, but little attention has been focused ongeometric characteristics, more specifically size distributions. However, the formation conditions of chondrues may also be
closely related to these propoerties above.
In the articles published so far on this topic, the characterization of geometric properties was almost exclusively limited to thetwo-dimensional size distribution of the plane sections of the spheres, measured by thin sections. However, these twodimensional size distributions do not match the true particle size distribution of the chondrules, and thus the previous flat
section size distributions are not directly suitable for drawing correct conclusions about the conditions under which they wereformed. The significance of the real particle size distributions may be further enhanced by the fact that, knowing these, it islikely that further classification of meteorites would be possible.
In the course of this research, our first goal was to find a relationship between the two-dimensional distributions of the sections
and the real particle size distribution of the chondrules. The question arises naturally as to whether it is possible to use thisrelationship to develop a procedure to determine the true particle size distribution of the concentrates from the twodimensional distributions. Since the preparation of thin grinds produces flat sections of the original condonants, the problem isessentially how to restore the real particle size distribution of the original spheres from a distribution made with the help of a
two-dimensional section.
The problem seems impossible at first hearing, since at pruning we in some sense "lose one dimension". If the diameter of achondrule is measured on the thin section, it can only be stated that the original diameter of the chondrule is surely greater thanor equal to this, but we cannot determine the original true size. Therefore, for some chondrules, the true size cannot be
determined from the size obtained during the section. However, this is not the case with distributions. Using a plausible
hypothesis, the relationship between the distributions can be written on the lost dimension, and thus, surprisingly in the light of
the above problem, the final question is answered positively, the original particle size distribution can be determined from the
distribution of thin sections.

Figure 1. A recording of a studied plane section.

The problem is fundamentally statistical and, as we will see, leads to the field of probability calculation, so that our answer
cannot be without the use of the tools of higher mathematics. We tested our results using Monte-Carlo simulations and found aperfect match between mathematical calculations and simulation results.
We intend to continue our research in several directions. One direction is to measure the distributions for as many thin sections
as possible and to determine the true particle size distributions from them. A recording of such a plane section is shown in
Figure 1.
Scientists in the fields of meteorite study do not always possess the advanced mathematics necessary to understand numeracy,
so as a continuation of the research, another goal in the future is to create an application that can determine the real particle
size distribution based on the measured distribution.

Multiscale characterization of the Asuka 12169 meteorite– rehearsal of Hayabusa2 returned sample analysis –M. Uesugi1, M. Ito2, N. Tomioka2, N. Imae3, A. Yamaguchi3, M. Kimura3, N. Shirai4, T. Ohigashi5, M-C. Liu6,
R.C Greenwood7, K. Uesugi1, A. Nakato8, K. Yogata8, H. Yuzawa5, Y. Kodama9,*, M. Yasutake1, K. Hirahara11, A. Takeuchi1,
I. Sakurai12, I. Okada12, Y. Karouji8, T. Yada8 and M. Abe8
1
JASRI/SPring-8, 2JAMSTEC Kochi, 3NIPR, 4Tokyo Met. Univ., 5UVSOR/IMS, 6UCLA, 7Open Univ.,8JAXA-ISAS,
9
MWJ, 11Osaka Univ., 12Nagoya Univ., *Toyo Corp.
Introduction
Regolith particles of the asteroid Ryugu were distributed to the initial analysis teams and the Phase2 curation teams in
mid 2021. The sample are free from terrestrial contaminations, and not exposed to the terrestrial atmosphere. In order tomaximize the scientific gain from the samples, we must (?) keep such high-level cleanness of the sample against the terrestrial
materials, throughout the analysis as long as possible. Prior to the analysis of the Hayabusa2 returned samples, the Phase2
curation Kochi team [1] conducted rehearsal analysis of a mm-sized fragment of Antarctic meteorite, Asuka (A) 12169 CM3.0,
by a series of multibeam micro analytical techniques prepared in each institute. The analytical flow starts from non-destructive
method such as a synchrotron radiation computed tomography (SR-CT) and SR x-ray diffraction (SR-XRD), to destructive but
high-resolution method such as scanning transmitted x-ray microscopy and near edge x-ray absorption fine structure (STXMNEXAFS), nano-scale secondary ion mass spectrometry (NanoSIMS) and transmission electron microscopy (TEM). We focus
on the characteristics of organic materials in aspect of relation to the structure and chemical composition of surrounding minerals.
Because A 12169 experienced only minimal aqueous alteration [2], organic materials in A 12169 would be pristine compared tothose of other meteorites. The study would help us for a better understanding of the evolution of organic material in Ryugu
samples.
Experiments
A small fragment of A 12169, 1mm x 1mm x 2mm, was examined by SR-CT with voxel size around 3 µm for the bulk
3D texture, and by SR-XRD for the bulk mineralogy. After the SR analysis, thesample was cut by a diamond wire saw without using glue or wax as well as
lubricants, to prevent contamination. Three ultrathin sections were picked up
from the matrix portions of the cut surface using focused ion beam (FIB). The
thin sections were investigated by STXM-NEXAFS, TEM, and NanoSIMS toanalyze organic materials.
Results
5µm
Figure 1 shows the STXM-NEXAFS images of A 12169, a part of thesequential analysis. Organic globules in A 12169, appear as spots of carbon
enriched regions in map of carbon concentration in Fig. 1, were abundantcompared to other CM chondrites. Some organic globules show a hollow
structure, which is well known as hollow-organic nano globule [e.g. 3-5]. Notethat region 1 in Fig. 1 shows two distinct areas with different carbon
concentrations. TEM analysis revealed that low carbon region consist mainly of
tochilinite-cronstedtite intergrowth (TCI). C-NEXAFS map also shows relatively
high abundance of carbonates in low carbon region than high carbon region.
Discussion
The low carbon region would be a part of a vein which had been formedby aqueous alteration, because of its high abundance of hydrous minerals.
Organic globules were almost absent inside the alteration vein. The result
indicates that the organic globules in high carbon region may be formed in
Figure 1. STXM-NEXAFS image of A 12169.
interplanetary and/or interstellar region prior to the aqueous alteration in theUpper: transmitted x-ray image of whole thinsection, middle: enlarged view of region 1 in top
parent body of A 12169, and were not robust against the aqueous alteration.
image, Bottom: carbon concentration image
References
obtained by C-NEXAFS. Bright spots indicated by[1] Ito M. et al. (2020) Hayabusa Symp. [2] Kimura M. et al. (2020) Polar Sci.
yellow circles show organic globules. Lower leftpart of image is depleted in carbon (alteration vein).
26:100565. [3] Garvie L. A. J. and Buseck P. R., (2006) MAPS 41:633. [4]Nakamura K. et al. (2006) Science, 314:1439. [5] De Gregorio B.T. et al.
(2013), MAPS 48:904.

Characterizing the Ryugu samples using the laboratory-based XRD
and the meteorite collections at NIPR
N. Imae1, A. Yamaguchi1, M. Kimura1, M. Ito2, N. Tomioka2, M. Uesugi3, N. Shirai4, T. Ohigashi5, M-C. Liu6, R.C.
Greenwood7, K. Uesugi3, A. Nakato8, K. Yogata8, H. Yuzawa5, Y. Kodama9,*, M. Yasutake3, K. Hirahara10, A. Takeuchi3,
I. Sakurai11, I. Okada11, Y. Karouji8, T. Yada8 and M. Abe8
1
NIPR, 2JAMSTEC Kochi, 3JASRI/SPring-8, 4Tokyo Met. Univ., 5UVSOR/IMS, 6UCLA, 7Open Univ., 8JAXA-ISAS,
9
MWJ, *Toyo Corp., 10Osaka Univ., 11Nagoya Univ.
Introduction
The laboratory-based X-ray diffraction is a useful technique for characterizing stony meteorites via whole powder
pattern fitting [e.g., 1–3] and µXRD [e.g., 4]. We have also shown that this method is useful for the classification of ordinarychondrites [5], shock effects of ordinary chondrites and eucrites [e.g., 6–7], thermal metamorphism of CO3 [8], and hydrous
alteration of CM2 [9]. The relative intensity ratio (RIR) method was used, and polished thin sections with large surface areas,
more than 1 cm2 were typically used. In the present study, we examined hydrous altered carbonaceous chondrites using thetechnique applicable to limited volumes, small surface area polished sections (several mm2) and ~0.5–10 mg fragments toward
the application to Ryugu. This report is part of the ongoing Phase2 Kochi advanced curation studies of returned Hayabusa 2
samples.
Experiments
We chose carbonaceous chondrites, CM (Y-791198, Y-793321, Y-82042, A-881655, A 12437, Jbilet Winselwan,
Murchison), CY (B-7904, Y-82162, Y-86029, Y-86720, Y-86737, Y-86789, Y 980115, Y 980134), CI (Orgueil), CO3 (ALH77307, A-881632), and C ung (Tagish Lake) for the present study. For each chondrite we prepared the following: a dry
polished mount embedded in epoxy resin and/or in sulfur, 0.5–6 mg powder in a non-reflection silicon plate (5 mm in diameterand 0.2 mm in depth, surface area 0.2 cm2) as well as a glass plate, and/or ~1–10 mg fragment on carbon nanotube (CNT) [10].
The Cu Ka X-ray beam (40 kV and 40 mA) of the X-ray diffractometer (SmartLab, RIGAKU) was broad, Bragg and Brentano(BB) method, or focused by a polycapillary unit (CBO-f unit), both in-plane rotation around the sample-area center, 20 rpm orlarger. The acquisition time was approximately 8 hours for BB and 40 hours for CBO-f, the 2q range was up to 80º for BB and
50º for CBO-f. Two techniques were used for preparing powdered samples: (1) only ~0.5-5 mg sample was pressed using asapphire glass plate on the silicon non-reflection silicon plate with the Miller index of (105), and (2) agate mortar and agate
pestle for sample mass of ≥~0.1 g was used. As well as small and limited samples, standard polished thin sections of Y-86720(74-1; 76 mm2), Y 980115 (,70-1; 98 mm2), B-7904 (,60-1; 144 mm2), ALH-77307 (,85-1; 50 mm2), A-881632 (,51-6; 100mm2), Y-791198 (,61-3; 70 mm2), Murchison (469 mm2), and Jbilet Winselwan (19 mm2) were also studied similarly forreference purposes.
Results
Diffractions from the epoxy resin of small samples (surface area with sub cm2) for both BB and CBO-f methods are
not intense. Many sulfur peaks from sulfur-embedded polished samples are observed and are necessary to be distinguishedwith peaks from the measured sample. Any fragment (~1–10 mg) on CNT normally shows the consistent diffraction patternfrom powder, but needs time and has a high background. The entire filling powder (~5–10 mg) by the non-reflection siliconplate gives higher intensity, and the background is minimal. Then, a very similar diffraction pattern to Y-82162 (CY with theheating stage II-III, [11]) was observed for Y-86029, Y-86737, Y 980115, and Y 980134, suggesting a pairing with ~5 mg
powder. The method was also applied to partially filling powder of Orgueil, ~0.5–1 mg, which generally showed a very similar
pattern to the entire filling case.
Discussion
Due to the limited amount of sample material that is available for study, 1 mg or less, then analysis using the nonreflection silicon plate technique is more suitable than employing a CNT. Because the more intense and higher angularresolution diffraction from powders is obtained. The press method of a tiny sample by sapphire glass on the non-reflection
silicon plate is suitable for the Ryugu analysis by the present powder method.

References[1] Dunn T. L. et al. (2010) M&PS 45:123. [2] Howard K. T. et al. (2011) GCA 75:2735. [3] King A. J. et al. (2021)
GCA 298:167. [4] Jenkins L. E. et al. (2019) M&PS 54:902. [5] Imae N. et al. (2019) M&PS 54:919. [6] Kanemaru R. et al.
(2020). Pol. Sci. 26:100605. [7] Imae N. and Kimura M. (2021) Am. Min. 106:1470. [8] Imae N. and Nakamuta Y. (2018)
M&PS 53:232. [9] Imae N. and Kimura M. (2020) 11th Symp. on Pol. Sci. [10] Uesugi M. et al. Rev. Sci. Instrum. 91:035107.
[11] Nakamura T. (2005) JMPS 100:260.

What is type 3.0 of chondrites?
Makoto Kimura
National Institute of Polar Research

Chondrites are classified into petrologic types 1-6. Among them, type 3 chondrites almost escaped thermal
metamorphism and aqueous alteration. Type 3 chondrites are classified into 3.0 to 3.9 [e.g., 1], reflecting thermal metamorphic
degree. Type 3.0 chondrites are further divided into 3.00 to 3.05 [2]. They are the most primitive chondrites to preserve thecharacteristic features of the constituent materials before the secondary processes in their parent bodies [e.g., 3]. However, theclassifications of some chondrites that experienced relatively low degrees of thermal metamorphism and aqueous alteration areoften problematic, for example, how to classify them and how to distinguish between types 3.0 and 2.9. Therefore, here I
reconsider the classification criteria of type 3.0. I also discuss the distribution of this type in chondrite groups. Here I include
types 3.00 to 3.05 into 3.0 together.
Type 3 chondrites are characterized by heterogeneous chemical compositions of silicate minerals and the preservationof primitive texture, such as well-defined chondrules and the occurrence of opaque matrix. In addition, type 3.0 chondrites
show the following characteristic features to distinguish it from types 3.1-3.9: Cr distribution in ferroan olivine, thethermoluminescence and cathodoluminescence features, the abundance of presolar grains, the occurrence of hydrated phases
especially in the matrix, and minor element contents in Fe-Ni metal [e.g., 2, 4]. Type 3.0 ordinary chondrites are alsocharacterized by the occurrence of nearly pure chromite [5]. All type 3.0 chondrites seem to contain amorphous materials in
the matrix [e.g., 6], although some altered chondrites also have it.
Recent studies showed that type 3.0 ordinary and carbonaceous chondrites also have other distinct features;
Plagioclase in them contains [ ]Si4O8 component and high MgO content [e.g., 7]. Fe-Ni metal shows the positive Ni-Co
correlation approximately along with the solar abundance. It abundantly contains some minor elements, such as Si, P, and Cr[8]. Since these features are not noticed in chondrites greater than or equal to type 3.1, they can be used to classify type 3.0
chondrites, in addition to the criteria mentioned above.
The problem is how to distinguish type 3.0 and less than 2.9 with aqueous alteration features. Although type 3.0
chondrites are hardly subjected to the secondary processes, all known such chondrites contain hydrous phases [e.g., 9]. If wedefine type 3.0 to escape the alteraion completely, all known type 3.0 chondrite must be reclassified into not greater than 2.9.
Since we need to avoid such confusion, I propose the new criteria for type 3.0; Silicate, oxide, metal, and sulfide minerals do
not show the alteration features under optical microscope and SEM observations. Melilite and anorthite in refractory inclusions
and chondrules, quickly altered phases, do not show the aqueous alteration features in type 3.0 chondrites. On the other hand,glass in chondrule and amorphous material in the matrix are partially, but never totally, hydrated in these chondrites. These
phases are the most susceptible to alteration. These classification criteria are consistent with those for not only CO andordinary chondrites but the recent classification of CR3.0 [10] and CM3.0 [11] chondrites. Abundant O-rich presolar grains inthese carbonaceous chondrites also support such criteria [12].
Although all chondrite groups include type 3 samples, type 3.0 has not been noticed in all kinds of chondrite. So far,type 3.0 is recognized from H, L, LL, CM, CO, CR, and Acfer 094. In the other chondrites, such as CV and E chondrites, notype 3.0 has been reported. Although we can not exclude the possibility of sampling problem, we already have abundantsamples for these chondrite groups without type 3.0 from Antarctica and other areas. Therefore, I suggest that such aheterogeneous distribution of type 3.0 reflects the degree of the secondary parent body process, such as thermal and/or shock
metamorphism.
References[1] Sears D. W. G. et al. 1991. Proc. Lunar and Planetary Science 21: 493-512. [2] Grossman J. N. and Brearley A. J. 2005.
Meteoritics & Planetary Science 40: 87-122. [3] Brearley A.J. 2017. 8h Symposium on Polar Science, National Institute ofPolar Research, [4] Huss G. R. et al. 2006. Thermal metamorphism in chondrites. In Meteorites and the Early Solar System [5]Kimura M. et al. 2006. Geochimica et Cosmochimica Acta 70: 5634-5650. [6] Dobrică E. and Brearley A. J. 2020. Meteoritics& Planetary Science 55: 649-668. [7] Siron G. et al. 2021. Geochimica et Cosmochimica Acta 293: 103-126. [8] Kimura M. et
al. 2008. Meteoritics and Planetary Science 43: 1161-1177. [9] Davidson J. et al. 2019. Geochimica et Cosmochimica Acta
265: 259-278. [10] Harju E. R. et al. 2014. Geochimica et Cosmochimica Acta 139: 267-292. [11] Kimura M. et al. 2020. Polar
Science 26: 100565. [12] Xu Y. et al. 2020. 11th Symposium on Polar Science, National Institute of Polar Research.

Chemical analyses of Fe – rich chondrule phases in Kaba (CV3) carbonaceous - chondrite.
Implications on the bulk elemental composition of terrestrial planetary cores.
P. Futó1 and A. Gucsik2
University of Debrecen, Cosmochemical Research Group, Department of Mineralogy and Geology, Debrecen, Egyetem tér 1.
H-4032, Hungary (dvision@citromail.hu)
2Eszterházy Károly Catholic University, Faculty of Natural Sciences, Institute of Chemistry and Physics, Department of
Physics, H-3300, Eger, Leányka utca 6-8.

1

Most chondrules in chondrites are dominated by olivine, pyroxene, and feldspar. They may also include metal alloys, sulfides,
nitrides, phosphides in varying proportions, which highlight to their formation in diverse physical and chemical environments(Hazen et al. 2021). Different metallic phases can be found in the mineral assemblages of chondrules. The metallic phases may
be Ni – rich metal (kamacite), moreover, troilite (FeS) and pentlandite (Fe, Ni)9S8 , which belong to the most common iron –nickel sulfides in chondrites.
We have performed several laboratory analyses to study metallic alloys in different mineral constituents of Kaba meteorite,
which is the one of the most primitive C – chondrite (Krot et al. 1998). Kaba contains Fe – rich chondrule phases representing
several characteristic mineral species in the Bali-type CV3 OxB chondritic material.
Analytical experiments: According to Gucsik et al. (2013) quantitative analyses for minor and major elements in olivine wereobtained by wavelength-dispersive spectrometry (WDS) linked to a JEOL JXA-8900R SEM at Okayama University of Science(Okayama, Japan). Operational conditions were: accelerating voltage of 15 kV and a probe current of 40 nA on a Faraday cup
equipped with PCD (probe current detector), using a focused beam. The ZAF program installed in the workstation was
employed for matrix corrections. The detection limit for quantitative analysis (WDS) ranged between 0.03 (light elements) and
0.04 (heavy elements) wt%, and was around 0.005 wt% for the qualitative measurements by EDS. The Secondary Electron
Image (SEI) and backscattered electron (BSE) images were captured by JSM-5410LV SEM.
Results: Three Fe – rich chondrule mineral phases have been indentified in Kaba. We have found that S, Ni and Co have thehigher relative abundance in the examined Fe-rich mineral phases of the chondrules in the Kaba c-chondrite (Table 1.).
FeO

Pentlandite

Kamacite

wt%

mol%

wt%

mol%

FeO

97.63

S

34.48

48.23

Fe

92.33

89.43

Na2O

0.52

Fe

44.76

35.94

Ni

4.67

4.3

MgO

0.28

Ni

19.45

14.86

Co

0.62

0.57

Cr2O3

0.51

Co

1.18

0.9

Mg

0.15

0.33

98.94

Si

0.14

0.22

Si

0.17

0.33

100.01

100.15

97.94

94.96

Table 1. mineral Fe-rich phases (FeO , pentlandite) (Fig.1) and Fe-Ni metal (kamacite) (Fig.2) in chondrules.

Conclusion: Although, CCs have not been derived from the central region of their parent bodies, the chemical composition of
their metallic mineral components in the primitive carbonaceous chondrite is similar to the iron – bearing meteorites. Thus, thecomplex mineralogy of c – chondrites with compositionally varying metallic phases implies on the characteristic bulk
elemental composition of the Fe - dominated metallic cores (with relatively high S, Ni and Co abundances) of chondrite parent
asteroids and more massive planetary bodies in the Solar System.
Acknowledgements - Authors express thanks to Taro Endo for his help by providing experimental data.
References
Gucsik A., Endo T., Nishido H., Ninagawa K., Kayama M., Berczi Sz., Kimura J., Miura H., Gyollai I., Simonia I., Rozsa
P., Posta J., Apai D., Mihalyi K., Nagy M., Ott U. Cathodoluminescence microscopy and spectroscopy of forsterite from Kaba
meteorite: An application to the study of hydrothermal alteration of parent body. Meteoritics & Planetary Science, 48. 25772596, 2013.
Hazen, R. M., Morrison S. M., Prabhu A. An evolutionary system of mineralogy. Part III: Primary chondrule mineralogy (4566to 4561 Ma), American Mineralogist, 106, 325 – 350, 2021.

Krot A. N., Petaev M. I., Scott E. R. D., Choi B., Zolensky M. E., Keil K. Progressive alteration in CV3 chondrites: Moreevidence for asteroidal alteration, Meteoritics & Planetary Science, 33. 1065-1085, 1998.

Figure 1. Fe -rich phases in chondrule.

Figure 2. Fe-Ni metal in chondrule.

On the bulk mineralogical composition of carbonaceous chondrites in low-Mg/Si planetarysystems.
P. Futó1 and A. Gucsik2
University of Debrecen, Cosmochemistry Research Group, Department of Mineralogy and Geology, Debrecen, Egyetem tér 1.
H-4032, Hungary (dvision@citromail.hu)
2Eszterházy Károly Catholic University, Faculty of Natural Sciences, Institute of Chemistry and Physics, Department of
Physics, H-3300, Eger, Leányka utca 6-8.

1

The chemical analyses of chondritic meteorites provides important informations to study the chemical evolution of the Solarsystem.
The Mg/Si ratio is the one of the most important elemental ratios, which controls the silicate mineralogy of terrestrial
planets.The obervations of stellar element abundances of FGK stars in the Solar neighbourhood show that the largest fractionof them have Mg/Si ratios between 1 and 2 (Delgado Mena et al. 2010). The majority of these stars have higher Mg/Si ratios
than the Solar value. At the same time, a smaller fraction of the observed stars exhibit low-Mg/Si ratios, which are smaller than1.
In the planetary systems, with lower Mg/Si ratio than Solar (Mg/Si=1.05) (Asplund et al. 2005), the mineral constituents of thechondrite components have been formed in a Mg-depleted chemical enviroment. The plausible composition of characteristic
mineral components of c-chondrites has been investigated as a function of a decreased Mg/Si molar ratio.
Chondrules are thought to be composed of Mg-rich olivine and pyroxenes, similarly to the mineralogy of c-chondrites withhigher Mg/Si ratio. However, the weight percent of pyroxenes has been calculated to be higher in the Mg-poor chondrules thanthat of the c-chondrites in the Solar System. Pyroxenes in chondrules of Mg-poor chondritic meteorites are consist of a higher
amount of high-Ca pyroxenes compared to that of the Mg-rich c-chondrites. Hence, the one of the main mineral component ofMg-poor chondrules is being made up mostly a solid solution between the diopside (CaMgSi 2O6) and hedenbergite(CaFeSi2O6) endmembers in the high-Ca pyroxene subgroup. Al-rich chondrules contain plagioclase including mostly andesineand oligoclase.
The mineral assemblage of CAIs (calcium-aluminium-rich inclusions) can be depleted in forsterite and anorthite, while it canbe richer in gehlenite (Ca2Al2SiO7) and diopsidic pyroxenes than chondrites in Solar-system. One group of CAIs may beenriched in grossite (CaAl4O7) containing the variable abundances of melilite, spinel (MgAl2O4) and hibonite (CaAl12O19).
AOAs (amoeboid olivine aggregates) are thought to have been depleted in forsterite, anorthite and Al-rich diopside. AOAs
have been characterized by a volatile- and moderately volatile- depleted elemental composition similarly to the CAIs.
The presented mineral composition of c-chondrites concerns the chondrite parent bodies with bulk Mg/Si values ranging from~ 0.9-1. The varying degrees of Mg-depletion can yield a majority of diposides in the mantle mineral composition of parent
asteroids.
A significant fraction of low-Mg/Si FGK stars in the Solar neighbourhood are thought to host rocky planets, which have Mgdepleted mantle and crustal mineralogy. The variation of Mg/Si ratio can also result in mineral diversity in rocky planetary
bodies if their bulk Mg/Si ratios are below 1. In the low-Mg/Si planetary systems, olivines ((Mg,Fe)2SiO4) and pyroxenes((Mg,Fe,Ca)SiO3) are also the two most abundant mineral groups in chondritic meteorites. However, the weight percent ratiosof their mineral components are different from those of chondrites, which had been formed in higher-Mg/Si planetary systems.
The Mg-depleted mantles in the parent asteroids of carbonaceous chondrites are likely to contain higher amount of diopsideand Na-pyroxenes (jadeite, aegirine).

References
Asplund, M., Grevesse, N., Sauval, J., The solar chemical composition, Cosmic Abundances as Records of Stellar Evolution
and Nucleosynthesis, ASP Conference series, 336, 25. 2005.
Delgado Mena, E., Israelian G., González Hernández J. I., Bond J. C., Santos N. C., Udry S., Mayor M., Chemical clues on theformation of planetary systems: C/O versus Mg/Si for HARPS GTO sample, The Astrophysical Journal, 725, 2349-2358, 2010.

An attempt for estimating aqueous alteration environment from Raman spectra of iron sulfide
Keisuke Narahara1, Shu-hei Urashima1, Akira Yamaguchi2, Naoya Imae2, and Hiroharu Yui1
1
Department of Chemistry, Graduate School of Science, Tokyo University of Science2
National Institute of Polar Research[Introduction] Aqueous alteration is one of the most important processes for the chemical evolution in asteroids. Because how
chemical reactions proceed is highly dependent on the environment such as temperature and pressure, several researchers have
tried to identify them on parent bodies of meteorites, especially for carbonaceous chondrites.1 However, pH and redox
potential of water, which are also important factors to determine the chemical reaction in aqueous solutions at the parent bodies,
are not well understood yet. This is because these aqueous parameters are difficult to be estimated from elemental composition,
degas profiles, or the presence/absence of specific minerals. We have recently attempted to estimate the aqueous parameters
through chemical composition of pyrrhotite. Pyrrhotite is one of iron sulfide minerals described as Fe1-xS. The factor “1-x” iscontinuously variable by the elution of Fe2+ to the aqueous solution surrounding it. Because the degree of the elution depends
on the pH and redox potential as well as the temperature, we hypothesized that they can be estimated from the chemicalcomposition of pyrrhotite. As a nondestructive and microscopic probe, we focused our attention to Raman spectroscopy
because meteorites are generally rare and heterogeneous. In this study, we measured Raman spectra of iron sulfides in Y
980115 as an example of carbonaceous chondrites possessing CI characteristics, i.e. extensively aqueously altered.
[Experimental] A chip of Y 980115 measured was loaned from National Institute of Polar Research. Raman spectra of theterrestrial pyrrhotites, which were collected at (A) Nikolaevskiy mine and (B) Kavalerovo mining district (both in Russia),
were also observed as references. Microscopic Raman measurement was performed on Raman-11i (Nanophoton) with anobjective lens of Nikon Plan Flour (×40 / NA 0.75, WD 0.66 mm) at 532 nm excitation (5 mW at the sample surface).
[Results and Discussion] Raman spectra obtained from yellowish, luster minerals on Y 980115 are shown in Figure 1a-d.
While the spectra in Figure 1a-c are similar to each other, the spectrum in Figure 1d was different from them. The former isassignable to pyrrhotite by the comparison with previously reported spectra of a carbonaceous chondrite LON 94101 (CM2,collected at Lonewolf Nunataks in Antarctica).2 The latter (in Figure 1d) was assigned to nickel-bearing iron sulfide,pentlandite (Fe, Ni)9S8, which should be excluded from the analysis. Slight variation of the peak frequency in Figure 1a-c
might reflect chemical composition (1-x) of pyrrhotite, but currently it is under debate. Figure 1e-f shows Raman spectra
observed for the terrestrial pyrrhotites (A and B). Although the spectrum for the fleshly cleaved surface (A, Figure 1e) was
different from those on Y 980115, the spectrum for the long-time air-exposed surface (B, Figure 1f) reproduces them. This
indicates that pyrrhotite on Y 980115 was oxidized to some extent. We are planning to compare Y 980115 pyrrhotites withvarious pyrrhotites which were exposed to different environment for elucidating the aqueous alteration environment of theparent body of Y 980115.

Figure 1 Raman spectra of iron sulfides on Y 980115 (a-d) and the terrestrial rocks (e: freshly cleaved surface, f: long-time air-exposed
surface).

References[1] Y. Homma et al., J. Mineral. Petrol. Sci., 110, 276 (2015) and references within.
[2] P. Lindgren et al., Meteorit. Planet Sci., 48, 1074 (2013).

Identifying Polymorphs of Serpentine with Micro-Raman Spectroscopy
Aruto Kashima1, Shu-hei Urashima1 and Hiroharu Yui1
Department of Chemistry, Graduate School of Science, Tokyo University of Science

1[Introduction] Serpentine, which is produced by aqueous alteration in meteorites and asteroids, is one of the most importantwater-bearing minerals.1 While its ideal chemical formula is simply described as Mg3Si2O5(OH)4, it has several crystal
polymorphs depending on the alteration environment such as temperature and pressure.2,3 This suggests that these
thermodynamic parameters at the aqueous alteration can be estimated from the serpentine polymorph. However, determinationof the polymorph is still challenging while several researchers have tried it.4,5 X-ray diffraction (XRD) is generally used toanalyze the crystal structure, but it is not suitable for serpentine polymorphs. Serpentine crystal is generally too small for XRD,
and there are no effective diffraction lines to unambiguously determine the crystal polymorphs.6 Here, we propose a new way
for the polymorph identification with micro-Raman spectroscopy. It is a non-destructive analytical method and its high spatial
resolution (~1 μm) enables us to selectively analyze small chips of serpentines even in heterogeneous meteorites.
[Experimental] Microscopic Raman measurement was performed on a Raman-11i (Nanophoton) equipped with microscopeof Eclipse Ti (Nikon). An objective lens of Nikon Plan Flour (40x/NA0.75 WD0.66), 532 nm or 785 nm laser with power of 720 mW at the sample face, and grating with 300 or 1200 grooves / mm were used. We purchased six serpentines collected fromseveral mines (at Canada, Norway, Hungary, etc.) for the measurements and used them to explore the differences in polymorph.
[Results and Discussion] The Raman spectra observed were shown in Figure 1a. While no significant difference was found at
a glance, the bands at ~390 and ~690 cm-1 showed subtle frequency-shift. These bands originate from stretching vibration ofcrosslinking Si-O-Si and bending vibration of SiO4 units. Because SiO4 units are an essential component of serpentine
structure, these bands are observable for any polymorphs and their vibrational frequency are not affected by cation substitution.
Instead, their frequency should be shifted with internal stress or bending of SiO4 sheets, which is directly related to thepolymorph structure. The frequency difference is more clearly seen in a biaxial plot of the peak frequencies for these modes(Figure 1b). While the frequency shift for each band is as small as 1-2 cm-1 so that they are hardly distinguishable, they areclearly separated in the biaxial plot. By macro/microscopic observation and the comparison of the spectra with those inliterature, we concluded that the peak separation in the biaxial plot is owing to polymorph specificity. Assignment for eachgroup in the biaxial plot and the detailed mechanism of the frequency shift will be described in the presentation.
(a)

(b)

Figure 1. (a) Raman spectra of serpentine, and (b) a biaxial plot of the peak frequency

References[1] A. J. Brearly, The Action of Water, Meteorites and the Early Solar System II, 587-624, 2006. [2] A. Putnis, An
Introduction to Mineral Sciences, 2008. [3] J. J. Hemley, J. W. Montoya, C. L. Christ and P. B. Hostetler, Mineral equilibria in
the MgO-SiO2-H2O system: talc-chrysotile-forsterite-brucite stability relations, Am. J. Sci, 277, 322-351, 1977. [4] C. Rinaudo,
D, Gastaldi and E. Belluso, Characterization of chrysotile, antigorite and lizardite by FT-Raman spectroscopy, Can. Mineral.,41, 883-890, 2003. [5] I. Sakaguchi, Y. Kouketsu, K. Michibayashi and R. W. Simon, Attenuated total refrection infrared(ATR-IR) spectroscopy of antigorite, chrysotile, and lizardite, J. Mineral. Petrol. Sci., 115, 303-312, 2020. [6] N. Kohyama,
Analysis of each polytype of serpentine minerals and the application to industrial health and geological science, Nendo Kagaku,
46, 33-39, 2007.

Erg Chech 002 – A New Member of the (Trachy-) Andesite Meteorite Clan
V.H. Hoffmann1, P. Schmitt-Kopplin2, K. Wimmer3, M. Kaliwoda1,4, W. Schmahl1,4. 1Faculty of Geosciences, Dep. Earth andEnvironmental Sciences, Univ. Munich; 2Helmholtz-Center, Munich; 3Nördlingen; 4Mineralogical State Collection Munich,
SNSB, Germany.
In recent years, a new and unique group of meteorites was identified, and classified within the ungrouped achondrites. These
meteorites are characterized by partly significantly high contents of plagioclase and/or various silica phases such as
cristobalite, trydimite (or sometimes quartz) and can be placed in the fields of andesites / trachyandesites. Almahata Sitta
paired individuals MS-MU 011 and MS-MU 035 were the first meteorites of this new type indicating silica-richtrachyandesitic magmatism, in this case possibly a near-crustal or upper mantle formation on the ureilite parent body [1-4].
NWA 7325/8409 and pairs (“green beauty”) represent another unique set of ungrouped achondrites and was classified as acumulate olivine-microgabbro containing more than 50% of feldspar – plagioclase - and clinopyroxene (diopside). Oxygenisotopy indicates similarities concerning formation / origin (likely parent body) to the two Almahata Sitta individuals [1-4].
NWA 11119 (and paired NWA 11558) attracted the meteorite community even further: the silica content of this stone wasfound to be as high as at least 30%, mainly characterized by cristobalite / trydimite and only traces of quartz. Further main
phases are plagioclase – anorthite – and diopside – a fascinating whitish – green rock. Practically all phases are frequently
found in small cavities in beautifully crystallized idiomorphic crystals. [1-5, and refs herein].
NWA 11575 represents another recent find in this direction, classified as an ungrouped achondrite, petrologically also a
trachyandesite with an oxygen isotopy linked to the LL region. [1,2].
Erg Chech 002 was found in 2020 in the Erg Chech region of the Sahara Desert in Algeria. A number of large stones (in kg
masses) and numerous smaller individuals have been found, about 32 kg in total (other sources speak about >40 kg). The
unique achondrite is proposed to be a likely fragment of a chondritic protoplanet which is over 4.5 billion years old [1,2,6-10].
Methods and techniques
Here we report results of our systematic investigations by LASER Raman spectroscopy – mineralogy and phase composition.
We have a number of EC 002 samples for our studies: several fragments and 2 larger pieces (slice and endcut of several grs in
mass, see figure 1).

Fig 1a: A 6,7 gr endcut (left side) and (b) a 3,3 gr slice (right side) of Erg Chech are some of the samples under study in our
project. Erg Chech 002 is characterized by the presence of large (green) pyroxene xenocrysts (mainly OPX) which can berecognized easily in both samples.
All Raman experiments have been performed on unprepared and uncoated samples in order to avoid any unwanted preparation
effects (eg alterations). We believe that the results are really representative because we used a number of different samples. We
used the 532nm LASER, Raman shifts were detected between 50-2500 cm-1 with a precision of +/- 1-2 cm-1, andmagnifications of 100-1000x (long distance lenses only), and a lateral resolution of 0.1 µm. Large maps up to 15x15 points in
2D/3D at high resolution allowed to also detect accessory phases / submicron articles and inclusions. Acquisition times of 1-3
sec and accumulation numbers of up to 5 have been used which allowed to obtain large numbers of Raman Spectra in shorttimes within the high resolution mappings, and therefore the results should be quite representative.

The priority of this part of our project was on the major phases and their distribution / intergrowth, and the comparison withseveral other trachyandesitic ungrouped achondritic meteorites (MS-MU 011/035, NWA 7325/8409 and NWA 11119) which
we have investigated in earlier projects [3-5].
The following phases could be found by our LASER Raman experiments in Erg Chech 002:
1. Major phases:
Orthopyroxene (OPX) (large xenocrysts)
Plagioclase / Oligoclase (partly in idiomorphic crystals in small cavities); no maskelynite.
Cristobalite / trydimite (no quartz)
Clinopyroxene (CPX) (partly in idiomorphic crystals in small cavities)
2. Accessory phases:
Troilite
Merrilite
Ca-Mg carbonates
Carbon phases (various)
Olivine-group phases (no Fe-Mg olivines, details under study)
Very few and tiny metal particles
Iron-oxides (chromite??)Erg Chech ist characterized by a low shock degree, terrestrial alteration effects can be neglected (very low degree). A
preliminary compilation of the magnetic susceptibility data which we have obtained on the above mentioned trachyandesitic
ungrouped achondrites under study in our projects and Erg Chech 002 gave the following result: the Log MS value of 3,17 (logspec. magnetic susceptibility in 10-9 m3/kg) of Erg Chech 002 is in the range of Log MS of MS-MU 011/035 but significantly
higher as log MS of NWA 11119 and NWA 7325/8409 [4,5]. This in reasonable agreement with the concentrations of the
major (ferri-o) magnetic phases in these achondritic meteorites.
References[1] Meteoritical Bulletin Database (10/2021): Almahata Sitta, NWA 7325/8409, NWA 11119 (and pairs), Erg Chech 002.
[2] www.meteoritestudies.com: Erg Chech 002 (10/2021).
[3] T. Mikouchi, A. Takenouchi, M.E. Zolensky, V.H. Hoffmann, 2018. Almahata Sitta MS-MU-011 and MS-MU-012:
formation conditions of two unusual rocks from the ureilite parent body. # 2383 and refs. herein.
[4] V.H. Hoffmann, T. Mikouchi, R. Hochleitner, M. Kaliwoda, K. Wimmer, 2018. Unique NWA 11119/11558, NWA 7325
(and pairs) and Almahata Sitta individuals MS-MU 011/035: new light on very early parent body differentiation. NASA/LPI
Differentiation 2018, # 4018 and refs. herein.
[5] V.H. Hoffmann, K. Wimmer, R. Hochleitner, M. Kaliwoda, 2018. NWA 11119 – probing an unknown early planetarybody? # 2468 and refs. herein.
[6] Barrat J.A., et al., 2021. A 4,565-My-old andesite from an extinct chondritic protoplanet. PNAS 118/11.
[7] Mikouchi T., Zolensky M.F., 2021. Mineralogy and cooling history of ungrouped achondrite Erg Chech 002. LPSC, #2457.
[8] Nicklas R.W., et al., 2021. Multi-stage differentiation history of andesitic achondrite Erg Chech 002. LPSC, #1074.
[9] Carpenter P.K., et al., 2021. Mineralogy and bulk elemental composition of ungrouped relatively sodic gabbroic achondrite
Erg Chech 002: an ancient planetary crustal sample? LPSC, #2205.
[10] Hamann C., et al., 2021. Petrography of fine-grained domains in ungrouped achondrite Erg Chech 002: evidence fordifferent cooling histories? 84th Meteor. Soc. Conf., #6236.

Chemical classifications of nine new iron meteorites from Yamato Mountains, Balchen and Nansen
Ice field
Naoki Shirai1, Akira Yamaguchi2, Makiko K. Haba3 and Shun Sekimoto4
1
Tokyo Metropolitan University, 2National Institute of Polar Research, 3Tokyo Institute of Technology, 4Institute for Integrated
Radiation and Nuclear Science, Kyoto University

Introduction
It was announced that seven and two iron meteorites were collected from ice field near the Yamato Mountains by JARE-41,
and from the Balchen and Nansen Ice Field by the Japan-Belgium joint expeditions, JARE-51 and JARE-54/BELARE 20122013, respectively [1]. In this report, chemical compositions of these iron meteorites were determined by using both INAA and
LA-ICPMS and these chemical characteristics were discussed in detail.
Experiments
Nine iron meteorites (Y 000311, Y 000479, Y 000537, Y 000547, Y 000587, Y 000703, Y 000846, A 09179 and A 12016)
were investigated in this study. All iron meteorites were analyzed by using both LA-ICPMS and INAA. INAA was performedat Institute for Integrated Radiation and Nuclear Science, Kyoto University. INAA procedure used in this study is basicallysimilar to that reported by Shirai et al. [2]. LA-ICPMS analysis were carried out using a Thermo ElementXR coupled to
CETAC LAS-213 at NIPR. Iron meteorites were ablated on line mode with spot size of 100 µm at a scan speedrate of 25-50µm/s. All analyses were performed with 20Hz repetition rate and 100% power output. Under these conditions, 31P, 53Cr, 57Fe,
59
Co, 60, 61, 62Ni, 63, 65Cu, 69, 71Ga, 73, 74Ge, 75As, 95Mo, 101, 102Ru, 103Rh, 105, 106Pd, 182, 183, 184W, 185, 187Re, 189, 190Os, 191, 193Ir, 194, 195Pt
and 197Au were monitored in low resolution (R = 300). Three to five separates lines were selected by avoiding of
microscopically inclusion of troilite and schreibersite and analyzed. For quantification, North Chile (IIAB), Hoba (IVB), NIST
663 are used as reference samples. Elemental abundances were determined from more than two isotopes for some elements,
average values are calculated.
Results and Discussion
IID: A 09179 has chemically similar to IID. As the IID iron meteorites have a high model abundance of schreibersite, their Pabundances were higher than 2400 ppm [3]. In contrast, A 09179 has a lower P abundance (800 ppm) than those of IID ironmeteorites. This difference is explained by avoiding schreibersite in LA-ICPMS analysis. Among IID iron meteorites, A 09179
has lower Au abundance than those reported values for IID iron meteorites, indicating that A 09179 was early crystallized
among the IID iron meteorites so far.
IIIAB: Y 000311, Y 000703 and A 12016 are plotted on the chemical trend (e.g., Au vs. Ge) defined by the IIIAB ironmeteorites, suggesting that these three iron meteorites are classified into IIIAB iron meteorites. Chemical compositions for Y
000311 and Y 000703 are consistent with each other. Based on sample location and similar chemical composition, Y 000703
are paired with Y 000311. Y 790724 was classified into previously observed IIIAB iron meteorite. As Ir abundance (9.25 ppm)
of Y 790724 [4] is higher than these two iron meteorites (7.36 ppm for Y 000311 and 7.27 ppm for Y 000703), these two ironmeteorites are not paired with Y 790724, and it is concluded Y 000311 and Y 000703 are new members of IIIAB ironmeteorites. A 12016 is the first IIIAB iron meteorite recovered from the Nansen Ice field.
IAB-ungrouped: The four iron meteorites (Y 000479, Y 000537, Y 000547 and Y 000587) analyzed in this study are plotted in
the area of IAB iron meteorites in plots of Ni, Co, Ga, As and Ir vs. Au. These six elements have been used as the best
taxonomic elements for classifications on IAB iron meteorite into a main group (MG) and five subgroups (sLL, sLM, sLH,
sHH and sHL) [5]. Worsham et al. [6] determined highly siderophile elements (HSEs) abundances for 58 IAB iron meteorites
and found that each subgroup has a characteristic CI-chondrite normalized abundance pattern for HSE. Y 000537 is plotted in
the area defined by sLM except for Co. CI-chondrite normalized values for Re, Os, Ir, Ru and Pt are consistent with each otherand lower than that of Pd. Y 000537 has a similar Pd abundance to those for sLM subgroups, while its CI-chondrite
normalized abundances patterns for HSE are different from those of sLM and similar to those for sHL and sHH subgroups.
The observed pattern of Y 000537 is broadly similar to magmatic iron meteorites such as IIAB and IIIAB, indicating that Y
000537 was fractionally crystallized. Three Yamato iron meteorites (Y 000479, Y 000547 and Y 000587) have similar
chemical compositions to each other, implying that Y 000547 and Y 000587 are paired with Y 000479. These three ironmeteorites are not plotted in the area defined by any IAB subgroups. CI-chondrite normalized abundance patterns for HSE ofthese three iron meteorites are similar to those for sHL and sHH subgroups. Thus, the four Yamato iron meteorites (Y 000479,
Y 000537, Y 000547 and Y 000587) are classified into IAB-ungrouped.
References[1] Meteorite Newsletter (2020) vol. 27. [2] Shirai N. et al. (2015) JRNC 303:1375-1380. [3] Buchwald V. F. (1975)
Handbook of Iron Meteorites. Univ. California Press. [4] Wasson J. T. and Kallemeyn G. W. (2002) GCA 66:2445-2473. [5]Worsham E. A. et al. (2016) GCA 188:261-283. [6] Wasson J. T. et al. (1989) GCA 53:735-744.