Crystal habit (tracht) of groundmass pyroxene crystals recorded magma ascent paths during the 2011 Shinmoedake eruption
文献类型：期刊论文
| 作者 | Okumura, Shota H.3; Mujin, Mayumi2; Tsuchiyama, Akira1,4,5; Miyake, Akira3 |
| 刊名 | AMERICAN MINERALOGIST
 |
| 出版日期 | 2024-02-26 |
| 卷号 | 109期号:2页码:325-338 |
| 关键词 | Pyroxene crystal habit crystal-size distribution nanolite magma ascent |
| ISSN号 | 0003-004X |
| DOI | 10.2138/am-2022-8765 |
| 英文摘要 | The morphologies and size distributions of groundmass crystals record conditions of magma ascent through volcanic conduits. However, morphological information (such as crystal shapes) has not been incorporated into crystal size distributions (CSDs). Here, we focused on the crystal habit, especially the shape variation due to the combination of (hk0) faces (hereafter "tracht") of pyroxene microlites and nano-crystals, and measured CSDs for each crystal habit (tracht) to more comprehensively characterize the crystallization kinetics. We refer to the CSDs measured for each tracht as "tracht-specific CSDs." Pyroclasts from the 2011 eruption of Shinmoedake (Kirishima volcano group, Japan) were examined by field-emission scanning electron microscopy, electron backscatter diffraction analysis, synchrotron radiation X-ray computed nanotomography, and transmission electron microscopy. The samples contain groundmass pyroxenes of two main trachts: octagonal prisms consisting of {100}, {010}, and {110} faces and hexagonal prism lacking {100} faces. The pumice clasts formed by different eruption styles showed different trends of tracht-specific CSDs. Sub-Plinian pumice clasts were characterized by octagonal microlites (1-10 mu m wide) and numerous hexagonal nano-crystals (0.2-2 mu m wide), and a Vulcanian pumice clast with the same glass composition showed the same characteristics. In contrast, Vulcanian pumice clasts with more evolved glass compositions contained mostly octagonal pyroxenes. The tracht-specific CSDs and growth zonations indicate a change from octagon-dominant to hexagon-dominant growth conditions during syneruptive ascent. We infer that the hexagonal tracht resulted from a large degree of effective undercooling due to rapid decompression in the shallow conduit. Moreover, the texture of the less-evolved Vulcanian pumice indicates that a portion of the magma erupted on the Vulcanian eruption followed almost the same ascent paths just prior to the fragmentation as those during the sub-Plinian eruptions, and thus the Vulcanian eruption may have involved the rapid ascent of deeper magma. We propose that tracht analyses of groundmass pyroxenes provide detailed information about time-evolution of magma conditions during syneruptive ascent. |
| WOS研究方向 | Geochemistry & Geophysics ; Mineralogy |
| 语种 | 英语 |
| WOS记录号 | WOS:001155433300012 |
| 源URL | [http://ir.gig.ac.cn/handle/344008/76197]  |
| 专题 | 中国科学院矿物学与成矿学重点实验室 |
| 通讯作者 | Okumura, Shota H. |
| 作者单位 | 1.CAS Ctr Excellence Deep Earth Sci, Guangzhou 510640, Peoples R China 2.Tohoku Univ, Grad Sch Sci, Dept Earth Sci, 6-3 Aramaki Aza Aoba,Aobaku, Sendai, Miyagi 9808578, Japan 3.Kyoto Univ, Grad Sch Sci, Dept Geol & Mineral, Kitashirakawaoiwake Cho,Sakyo Ku, Kyoto 6068502, Japan 4.Ritsumeikan Univ, Res Org Sci & Technol, 1-1-1 Nojihigashi, Kusatsu, Shiga 5258577, Japan 5.Chinese Acad Sci, Guangzhou Inst Geochem, CAS Key Lab Mineral & Metallogeny, Guangdong Prov Key Lab Mineral Phys & Mat, 511 Kehua St, Guangzhou 510640, Peoples R China |
| 推荐引用方式 GB/T 7714 | Okumura, Shota H.,Mujin, Mayumi,Tsuchiyama, Akira,et al. Crystal habit (tracht) of groundmass pyroxene crystals recorded magma ascent paths during the 2011 Shinmoedake eruption[J]. AMERICAN MINERALOGIST,2024,109(2):325-338. |
| APA | Okumura, Shota H.,Mujin, Mayumi,Tsuchiyama, Akira,&Miyake, Akira.(2024).Crystal habit (tracht) of groundmass pyroxene crystals recorded magma ascent paths during the 2011 Shinmoedake eruption.AMERICAN MINERALOGIST,109(2),325-338. |
| MLA | Okumura, Shota H.,et al."Crystal habit (tracht) of groundmass pyroxene crystals recorded magma ascent paths during the 2011 Shinmoedake eruption".AMERICAN MINERALOGIST 109.2(2024):325-338. |
入库方式： OAI收割
来源：广州地球化学研究所
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