Three-dimensional textures of Ryugu samples and their implications for the evolution of aqueous alteration in the Ryugu parent body
文献类型：期刊论文
| 作者 | Tsuchiyama, Akira15,16,17; Matsumoto, Megumi18; Matsuno, Junya19; Yasutake, Masahiro20; Nakamura, Tomoki18; Noguchi, Takaaki21; Miyake, Akira21,23; Uesugi, Kentaro20; Takeuchi, Akihisa20; Okumura, Shota21 |
| 刊名 | GEOCHIMICA ET COSMOCHIMICA ACTA
 |
| 出版日期 | 2024-06-15 |
| 卷号 | 375页码:146-172 |
| 关键词 | Hayabusa2 X-ray nanotomography CI chondrites Three-dimensional morphology of minerals Precipitation sequence |
| ISSN号 | 0016-7037 |
| DOI | 10.1016/j.gca.2024.03.032 |
| 英文摘要 | Samples collected from the surface/subsurface of C -type asteroid 162173 Ryugu by the Hayabusa2 mission were nondestructively analyzed in three dimensions (3D). Seventy-three small particles (approximately 10-180 mu m in size) were observed using X-ray nanotomography, with an effective spatial resolution of approximately 200 nm. Detailed descriptions of these samples in terms of mineralogy, petrology, and variations among particles were reported. The 57 most common particles consisted of a phyllosilicate matrix containing mineral grains, mainly magnetite, pyrrhotite, dolomite and apatite. The remaining particles were mostly monomineralic particles (pyrrhotite, dolomite, breunnerite, apatite, and Mg-Na phosphate) with two unique particles (calcite in a Al 2 Si 2 O 5 (OH) 4 matrix, and CaCO 3 , phyllosilicate, and tochilinite-chronstedtite inclusions in a carbonaceous material matrix). The results confirmed that the samples correspond to Ivuna-type carbonaceous chondrites (CI chondrites) or related materials. Many small inclusions of voids and carbonaceous materials were detected in pyrrhotite, dolomite, breunnerite, and apatite. However, no fluid inclusions were observed, except for those in pyrrhotite that have already been reported. Magnetite exhibited a wide variety of morphologies, from irregular shapes (spherulites, framboids, plaquettes, and whiskers) to euhedral shapes (equants, rods, and cubes), along with transitional shapes. In contrast, the other minerals exhibit predominantly euhedral shapes (pyrrhotite: pseudo -hexagonal plates, dolomite: flattened rhombohedrons, breunnerite: largely flattened rhombohedrons, and apatite: hexagonal prisms) or aggregates of faceted crystals, except for Mg-Na phosphate. The matrices were heterogeneous with variable phyllosilicate particle sizes, Mg/Fe ratios, density (1.7 +/- 0.2 g/cm 3 ), nanoporosities (36 +/- 9 %), and abundances of nanograins of Fe(-Ni) sulfides. The macroporosity of the particles was estimated as 12 +/- 4 %. The observed textural relationships among the minerals suggest a precipitation sequence of: magnetite (spherulite -> plaquette/framboid -> rod/equant) -> pyrrhotite (pentlandite -> pyrrhotite) -> apatite -> dolomite -> breunnerite -> coarse phyllosilicates. Fe -bearing olivine (or low -Ca pyroxene) might have precipitated later than dolomite, indicating a high Mg activity in the aqueous solution. This precipitation sequence corresponds to a transition from irregular crystal forms (as seen in some magnetite) to regular forms of euhedral crystals (observed in some magnetite and other minerals). Based on the precipitation sequence and mineral morphologies, together with previously reported observations, a model for aqueous alteration in the Ryugu parent body was proposed as follows: CO 2 -H 2 O ice, amorphous silicates (GEMS -like material), and some minerals (mostly metal, sulfides, and anhydrous silicates) accumulated to form the parent body of Ryugu. Amorphous silicates and Fe-Ni metal quickly dissolved into the melted ice to form a highly supersaturated aqueous solution. Poorlycrystalized phyllosilicate and spherulitic magnetite precipitated first, followed by plaquette/framboidal magnetites with decreasing degree of supersaturation due to precipitation. Pseudo -hexagonal pyrrhotite plates were formed by dissolution and reprecipitation under relatively low supersaturation. Subsequently, apatite, dolomite, and breunnerite precipitated in this order in response to decreasing supersaturation. |
| WOS研究方向 | Geochemistry & Geophysics |
| 语种 | 英语 |
| WOS记录号 | WOS:001251445200001 |
| 源URL | [http://ir.gig.ac.cn/handle/344008/78249]  |
| 专题 | 中国科学院矿物学与成矿学重点实验室 |
| 通讯作者 | Tsuchiyama, Akira |
| 作者单位 | 1.Ist Nazl Astrofis, Ist Astrofis & Planetol Spaziali, Rome, Italy 2.Shizuoka Univ, Fac Sci, Dept Geosci, Shizuoka 4228529, Japan 3.Kindai Univ, Fac Engn, Higashihiroshima 7392116, Japan 4.Univ Paris Saclay, IAS, CNRS, Gif Sur Yvette, France 5.NASA, Johnson Space Ctr, ARES, Houston, TX 77058 USA 6.Natl Inst Adv Ind Sci & Technol, Inst Geol & Geoinformat, Tsukuba 3058567, Japan 7.Meiji Univ, Grad Sch Adv Math Sci, Nakano 1648525, Japan 8.Hokkaido Univ, Dept Earth & Planetary Sci, Sapporo 0600810, Japan 9.Kyushu Univ, Dept Earth & Planetary Sci, Fukuoka 8190395, Japan 10.Hiroshima Univ, Dept Earth & Planetary Syst Sci, 1-3-1 Kagamiyama, Higashihiroshima 7398526, Japan |
| 推荐引用方式 GB/T 7714 | Tsuchiyama, Akira,Matsumoto, Megumi,Matsuno, Junya,et al. Three-dimensional textures of Ryugu samples and their implications for the evolution of aqueous alteration in the Ryugu parent body[J]. GEOCHIMICA ET COSMOCHIMICA ACTA,2024,375:146-172. |
| APA | Tsuchiyama, Akira.,Matsumoto, Megumi.,Matsuno, Junya.,Yasutake, Masahiro.,Nakamura, Tomoki.,...&Tsuda, Yuichi.(2024).Three-dimensional textures of Ryugu samples and their implications for the evolution of aqueous alteration in the Ryugu parent body.GEOCHIMICA ET COSMOCHIMICA ACTA,375,146-172. |
| MLA | Tsuchiyama, Akira,et al."Three-dimensional textures of Ryugu samples and their implications for the evolution of aqueous alteration in the Ryugu parent body".GEOCHIMICA ET COSMOCHIMICA ACTA 375(2024):146-172. |
入库方式： OAI收割
来源：广州地球化学研究所
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