T. Michalik, A. Maturilli, E. A. Cloutis, K. Stephan, R. Milke, K.-D. Matz, R. Jaumann, L. Hecht, H. Hiesinger, K. A. Otto
Pitted impact deposits on Vesta show higher reflectance and pyroxene absorption band strengths compared to their immediate surroundings and other typical Vestan materials. We investigated whether heating to different temperatures for different durations of Vestan regolith analog materials can reproduce these spectral characteristics using mixtures of HEDs, the carbonaceous chondrite Murchison, and terrestrial analogs. We find no consistent spectral trend due merely to temperature increases, but observed that the interiors of many heated samples show both higher reflectance and pyroxene band I strength than their heated surfaces. With electron probe microanalysis, we additionally observe the formation of hematite, which could account for the higher reflectance. The presence of hematite indicates oxidation occurring in the sample interiors. In combination with heat, this might cause the increase of pyroxene band strengths through migration of iron cations. The effect grows larger with increasing temperature and duration, although temperature appears to play the more dominant role. A higher proportion of Murchison or the terrestrial carbonaceous chondrite analog within our mixtures also appears to facilitate the onset of oxidation. Our observations suggest that both the introduction of exogenic material on Vesta as well as the heating from impacts were necessary to enable the process (possibly oxidation) causing the observed spectral changes.
灶神星上的凹坑状撞击沉积物与其周围环境和其他典型的灶神星材料相比,显示出更高的反射率和辉石吸收带强度。我们使用 HEDs、碳质软玉 Murchison 和陆地类似物的混合物,研究了将灶神星碎屑岩类似物加热到不同温度并持续不同时间是否能再现这些光谱特征。我们没有发现仅仅由于温度升高而导致的一致的光谱趋势,但观察到许多加热样品的内部显示出比加热表面更高的反射率和辉石带 I 强度。通过电子探针显微分析,我们还观察到赤铁矿的形成,这可能是反射率较高的原因。赤铁矿的存在表明样品内部发生了氧化。结合热量,这可能会通过铁阳离子的迁移导致辉石带强度的增加。随着温度的升高和时间的延长,这种影响会越来越大,不过温度似乎起着更加主要的作用。在我们的混合物中,较高比例的默奇森或陆地碳质软玉类似物似乎也会促进氧化的开始。我们的观测结果表明,灶神星上外生物质的引入以及撞击产生的热量对于实现导致观测到的光谱变化的过程(可能是氧化)都是必要的。
{"title":"Laboratory VIS–NIR reflectance measurements of heated Vesta regolith analogs: Unraveling the spectral properties of the pitted impact deposits on Vesta","authors":"T. Michalik, A. Maturilli, E. A. Cloutis, K. Stephan, R. Milke, K.-D. Matz, R. Jaumann, L. Hecht, H. Hiesinger, K. A. Otto","doi":"10.1111/maps.14156","DOIUrl":"10.1111/maps.14156","url":null,"abstract":"<p>Pitted impact deposits on Vesta show higher reflectance and pyroxene absorption band strengths compared to their immediate surroundings and other typical Vestan materials. We investigated whether heating to different temperatures for different durations of Vestan regolith analog materials can reproduce these spectral characteristics using mixtures of HEDs, the carbonaceous chondrite Murchison, and terrestrial analogs. We find no consistent spectral trend due merely to temperature increases, but observed that the interiors of many heated samples show both higher reflectance and pyroxene band I strength than their heated surfaces. With electron probe microanalysis, we additionally observe the formation of hematite, which could account for the higher reflectance. The presence of hematite indicates oxidation occurring in the sample interiors. In combination with heat, this might cause the increase of pyroxene band strengths through migration of iron cations. The effect grows larger with increasing temperature and duration, although temperature appears to play the more dominant role. A higher proportion of Murchison or the terrestrial carbonaceous chondrite analog within our mixtures also appears to facilitate the onset of oxidation. Our observations suggest that both the introduction of exogenic material on Vesta as well as the heating from impacts were necessary to enable the process (possibly oxidation) causing the observed spectral changes.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 6","pages":"1421-1454"},"PeriodicalIF":2.2,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.14156","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140738486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Noriko T. Kita, Kouki Kitajima, Kazuhide Nagashima, Noriyuki Kawasaki, Naoya Sakamoto, Wataru Fujiya, Yoshinari Abe, Jérôme Aléon, Conel M. O'D. Alexander, Sachiko Amari, Yuri Amelin, Ken-ichi Bajo, Martin Bizzarro, Audrey Bouvier, Richard W. Carlson, Marc Chaussidon, Byeon-Gak Choi, Nicolas Dauphas, Andrew M. Davis, Tommaso Di Rocco, Ryota Fukai, Ikshu Gautam, Makiko K. Haba, Yuki Hibiya, Hiroshi Hidaka, Hisashi Homma, Peter Hoppe, Gary R. Huss, Kiyohiro Ichida, Tsuyoshi Iizuka, Trevor R. Ireland, Akira Ishikawa, Shoichi Itoh, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming-Chang Liu, Yuki Masuda, Kevin D. McKeegan, Mayu Morita, Kazuko Motomura, Frédéric Moynier, Izumi Nakai, Ann Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Sara S. Russell, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Sohei Wada, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, Tetsuya Yokoyama, Shigekazu Yoneda, Edward D. Young, Hiroharu Yui, Ai-Cheng Zhang, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Ryuji Okazaki, Kanako Sakamoto, Hikaru Yabuta, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tatsuaki Okada, Toru Yada, Kasumi Yogata, Satoru Nakazawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Sei-ichiro Watanabe, Makoto Yoshikawa, Shogo Tachibana, Hisayoshi Yurimoto
Oxygen 3-isotope ratios of magnetite and carbonates in aqueously altered carbonaceous chondrites provide important clues to understanding the evolution of the fluid in the asteroidal parent bodies. We conducted oxygen 3-isotope analyses of magnetite, dolomite, and breunnerite in two sections of asteroid Ryugu returned samples, A0058 and C0002, using a secondary ion mass spectrometer (SIMS). Magnetite was analyzed by using a lower primary ion energy that reduced instrumental biases due to the crystal orientation effect. We found two groups of magnetite data identified from the SIMS pit morphologies: (1) higher δ18O (from 3‰ to 7‰) and ∆17O (~2‰) with porous SIMS pits mostly from spherulitic magnetite, and (2) lower δ18O (~ −3‰) and variable ∆17O (0‰–2‰) mostly from euhedral magnetite. Dolomite and breunnerite analyses were conducted using multi-collection Faraday cup detectors with precisions ≤0.3‰. The instrumental bias correction was applied based on carbonate compositions in two ways, using Fe and (Fe + Mn) contents, respectively, because Ryugu dolomite contains higher amounts of Mn than the terrestrial standard. Results of dolomite and breunnerite analyses show a narrow range of ∆17O; 0.0‰–0.3‰ for dolomite in A0058 and 0.2‰–0.8‰ for dolomite and breunnerite in C0002. The majority of breunnerite, including large ≥100 μm grains, show systematically lower δ18O (~21‰) than dolomite (25‰–30‰ and 23‰–27‰ depending on the instrumental bias corrections). The equilibrium temperatures between magnetite and dolomite from the coarse-grained lithology in A0058 are calculated to be 51 ± 11°C and 78 ± 14°C, depending on the instrumental bias correction scheme for dolomite; a reliable temperature estimate would require a Mn-bearing dolomite standard to evaluate the instrumental bias corrections, which is not currently available. These results indicate that the oxygen isotope ratios of aqueous fluids in the Ryugu parent asteroid were isotopically heterogeneous, either spatially, or temporary. Initial water ice accreted to the Ryugu parent body might have ∆17O > 2‰ that was melted and interacted with anhydrous solids with the initial ∆17O < 0‰. In the early stage of aqueous alteration, spherulitic magnetite and calcite formed from aqueous fluid with ∆17O ~ 2‰ that was produced by isotope exchange between water (∆17O > 2‰) and anhydrous solids (∆17O < 0‰). Dolomite and breunnerite, along with some magnetite, formed at the later stage of aqueous alteration under higher water-to-rock ratios where the oxygen isotope ratios were nearly at equilibrium between fluid and solid phases. Including literature data, δ18O of carbonates decreased in the order calcite, dolomite, and breunnerite, suggesting that the temperature of alteration might have increased with the degree of aqueous alteration.
{"title":"Disequilibrium oxygen isotope distribution among aqueously altered minerals in Ryugu asteroid returned samples","authors":"Noriko T. Kita, Kouki Kitajima, Kazuhide Nagashima, Noriyuki Kawasaki, Naoya Sakamoto, Wataru Fujiya, Yoshinari Abe, Jérôme Aléon, Conel M. O'D. Alexander, Sachiko Amari, Yuri Amelin, Ken-ichi Bajo, Martin Bizzarro, Audrey Bouvier, Richard W. Carlson, Marc Chaussidon, Byeon-Gak Choi, Nicolas Dauphas, Andrew M. Davis, Tommaso Di Rocco, Ryota Fukai, Ikshu Gautam, Makiko K. Haba, Yuki Hibiya, Hiroshi Hidaka, Hisashi Homma, Peter Hoppe, Gary R. Huss, Kiyohiro Ichida, Tsuyoshi Iizuka, Trevor R. Ireland, Akira Ishikawa, Shoichi Itoh, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming-Chang Liu, Yuki Masuda, Kevin D. McKeegan, Mayu Morita, Kazuko Motomura, Frédéric Moynier, Izumi Nakai, Ann Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Sara S. Russell, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Sohei Wada, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, Tetsuya Yokoyama, Shigekazu Yoneda, Edward D. Young, Hiroharu Yui, Ai-Cheng Zhang, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Ryuji Okazaki, Kanako Sakamoto, Hikaru Yabuta, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tatsuaki Okada, Toru Yada, Kasumi Yogata, Satoru Nakazawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Sei-ichiro Watanabe, Makoto Yoshikawa, Shogo Tachibana, Hisayoshi Yurimoto","doi":"10.1111/maps.14163","DOIUrl":"10.1111/maps.14163","url":null,"abstract":"<p>Oxygen 3-isotope ratios of magnetite and carbonates in aqueously altered carbonaceous chondrites provide important clues to understanding the evolution of the fluid in the asteroidal parent bodies. We conducted oxygen 3-isotope analyses of magnetite, dolomite, and breunnerite in two sections of asteroid Ryugu returned samples, A0058 and C0002, using a secondary ion mass spectrometer (SIMS). Magnetite was analyzed by using a lower primary ion energy that reduced instrumental biases due to the crystal orientation effect. We found two groups of magnetite data identified from the SIMS pit morphologies: (1) higher δ<sup>18</sup>O (from 3‰ to 7‰) and ∆<sup>17</sup>O (~2‰) with porous SIMS pits mostly from spherulitic magnetite, and (2) lower δ<sup>18</sup>O (~ −3‰) and variable ∆<sup>17</sup>O (0‰–2‰) mostly from euhedral magnetite. Dolomite and breunnerite analyses were conducted using multi-collection Faraday cup detectors with precisions ≤0.3‰. The instrumental bias correction was applied based on carbonate compositions in two ways, using Fe and (Fe + Mn) contents, respectively, because Ryugu dolomite contains higher amounts of Mn than the terrestrial standard. Results of dolomite and breunnerite analyses show a narrow range of ∆<sup>17</sup>O; 0.0‰–0.3‰ for dolomite in A0058 and 0.2‰–0.8‰ for dolomite and breunnerite in C0002. The majority of breunnerite, including large ≥100 μm grains, show systematically lower δ<sup>18</sup>O (~21‰) than dolomite (25‰–30‰ and 23‰–27‰ depending on the instrumental bias corrections). The equilibrium temperatures between magnetite and dolomite from the coarse-grained lithology in A0058 are calculated to be 51 ± 11°C and 78 ± 14°C, depending on the instrumental bias correction scheme for dolomite; a reliable temperature estimate would require a Mn-bearing dolomite standard to evaluate the instrumental bias corrections, which is not currently available. These results indicate that the oxygen isotope ratios of aqueous fluids in the Ryugu parent asteroid were isotopically heterogeneous, either spatially, or temporary. Initial water ice accreted to the Ryugu parent body might have ∆<sup>17</sup>O > 2‰ that was melted and interacted with anhydrous solids with the initial ∆<sup>17</sup>O < 0‰. In the early stage of aqueous alteration, spherulitic magnetite and calcite formed from aqueous fluid with ∆<sup>17</sup>O ~ 2‰ that was produced by isotope exchange between water (∆<sup>17</sup>O > 2‰) and anhydrous solids (∆<sup>17</sup>O < 0‰). Dolomite and breunnerite, along with some magnetite, formed at the later stage of aqueous alteration under higher water-to-rock ratios where the oxygen isotope ratios were nearly at equilibrium between fluid and solid phases. Including literature data, δ<sup>18</sup>O of carbonates decreased in the order calcite, dolomite, and breunnerite, suggesting that the temperature of alteration might have increased with the degree of aqueous alteration.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 8","pages":"2097-2116"},"PeriodicalIF":2.2,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.14163","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140796932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. A. Eckley, R. A. Ketcham, Y. Liu, J. Gross, F. M. McCubbin
Shergottites are mafic to ultramafic igneous rocks that represent the majority of known Martian meteorites. They are subdivided into gabbroic, poikilitic, basaltic, and olivine–phyric categories based on differences in mineralogy and textures. Their geologic contexts are unknown, so analyses of crystal sizes and preferred orientations have commonly been used to infer where shergottites solidified. Such environments range from subsurface cumulates to shallow intrusives to extrusive lava flows, which all have contrasting implications for interactions with crustal material, cooling histories, and potential in situ exposure at the surface. In this study, we present a novel three-dimensional (3-D) approach to better understand the solidification environments of these samples and improve our knowledge of shergottites' geologic contexts. Shape preferred orientations of most phases and crystal size distributions of late-forming minerals were measured in 3-D using X-ray computed tomography (CT) on eight shergottites representing the gabbroic, poikilitic, basaltic, and olivine–phyric categories. Our analyses show that highly anisotropic, rod-like pyroxene crystals are strongly foliated in the gabbroic samples but have a weaker foliation and a mild lineation in the basaltic sample, indicating a directional flow component in the latter. Star volume distribution analyses revealed that most phases (maskelynite, pyroxene, olivine, and oxides/sulfides) preserve a foliated texture with variable strengths, and that the phases within individual samples are strongly to moderately aligned with respect to one another. In combination with relative cooling rates during the final stages of crystallization determined from interstitial oxide/sulfide crystal size distribution analyses, these results indicate that the olivine–phyric samples were emplaced as shallow intrusives (e.g., dikes/sills) and that the gabbroic, poikilitic, and basaltic samples were emplaced in deeper subsurface environments.
谢尔戈特岩是黑云母至超黑云母火成岩,占已知火星陨石的大多数。根据矿物学和质地的不同,它们又被细分为辉长岩、辉绿岩、玄武岩和橄榄斑岩等类别。这些陨石的地质环境尚不清楚,因此通常使用晶体大小和偏好方向的分析来推断舍尔格特石的凝固地点。这些环境包括地表下的积岩、浅侵入岩和喷出熔岩流,它们对与地壳物质的相互作用、冷却历史和地表的潜在原位暴露都有不同的影响。在这项研究中,我们提出了一种新颖的三维(3-D)方法,以更好地了解这些样品的凝固环境,并增进我们对舍尔格特岩地质背景的了解。我们使用 X 射线计算机断层扫描(CT)技术,对代表辉长岩、辉绿岩、玄武岩和橄榄斑岩类别的八种谢尔戈特岩进行了三维测量,结果显示大多数相的形状优先取向和后期形成矿物的晶体尺寸分布。我们的分析表明,在辉长岩样品中,高度各向异性的棒状辉石晶体具有强烈的褶皱,但在玄武岩样品中,褶皱较弱,线纹较轻,这表明后者中存在定向流动成分。星体体积分布分析表明,大多数相(蒙德拉石、辉石、橄榄石和氧化物/硫化物)都保留了强度不等的褶皱纹理,而且各个样品中的相彼此间的排列从强烈到适度不等。结合根据间隙氧化物/硫化物晶体尺寸分布分析确定的结晶最后阶段的相对冷却率,这些结果表明橄榄石斑岩样品是作为浅侵入体(如尖晶石/闪长岩)堆积的,而辉长岩、辉绿岩和玄武岩样品是在较深的地下环境中堆积的。
{"title":"Emplacement of shergottites in the Martian crust inferred from three-dimensional petrofabric and crystal size distribution analyses","authors":"S. A. Eckley, R. A. Ketcham, Y. Liu, J. Gross, F. M. McCubbin","doi":"10.1111/maps.14165","DOIUrl":"https://doi.org/10.1111/maps.14165","url":null,"abstract":"<p>Shergottites are mafic to ultramafic igneous rocks that represent the majority of known Martian meteorites. They are subdivided into gabbroic, poikilitic, basaltic, and olivine–phyric categories based on differences in mineralogy and textures. Their geologic contexts are unknown, so analyses of crystal sizes and preferred orientations have commonly been used to infer where shergottites solidified. Such environments range from subsurface cumulates to shallow intrusives to extrusive lava flows, which all have contrasting implications for interactions with crustal material, cooling histories, and potential in situ exposure at the surface. In this study, we present a novel three-dimensional (3-D) approach to better understand the solidification environments of these samples and improve our knowledge of shergottites' geologic contexts. Shape preferred orientations of most phases and crystal size distributions of late-forming minerals were measured in 3-D using X-ray computed tomography (CT) on eight shergottites representing the gabbroic, poikilitic, basaltic, and olivine–phyric categories. Our analyses show that highly anisotropic, rod-like pyroxene crystals are strongly foliated in the gabbroic samples but have a weaker foliation and a mild lineation in the basaltic sample, indicating a directional flow component in the latter. Star volume distribution analyses revealed that most phases (maskelynite, pyroxene, olivine, and oxides/sulfides) preserve a foliated texture with variable strengths, and that the phases within individual samples are strongly to moderately aligned with respect to one another. In combination with relative cooling rates during the final stages of crystallization determined from interstitial oxide/sulfide crystal size distribution analyses, these results indicate that the olivine–phyric samples were emplaced as shallow intrusives (e.g., dikes/sills) and that the gabbroic, poikilitic, and basaltic samples were emplaced in deeper subsurface environments.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 7","pages":"1523-1545"},"PeriodicalIF":2.2,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141583934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The 2021 Leonard Medal was awarded to Dr. Katharina Lodders, in person, at the 2021 Annual Meeting of the Meteoritical Society in Chicago, IL, USA. This is the citation presented for Dr. Lodders.
{"title":"Citation for Dr. Katharina Lodders, Leonard Medalist, 2021","authors":"Denton S. Ebel","doi":"10.1111/maps.14158","DOIUrl":"10.1111/maps.14158","url":null,"abstract":"<p>The 2021 Leonard Medal was awarded to Dr. Katharina Lodders, in person, at the 2021 Annual Meeting of the Meteoritical Society in Chicago, IL, USA. This is the citation presented for Dr. Lodders.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 S1","pages":"A469-A472"},"PeriodicalIF":2.2,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140373605","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The microstructural characterization of lunar agglutinate samples serves many essential purposes in lunar science and cosmochemistry, from understanding the formation process of lunar regolith to preparing for human activity on the Moon. In this study, an advanced correlative characterization methodology was employed to examine the microstructure of a lunar agglutinate particle retrieved from the Apollo 11 mission. The multimodal characterization efforts were centered around 3-D x-ray computed tomography (XCT) and were complemented by 2-D techniques, including scanning electron microscopy and energy-dispersive x-ray spectroscopy. The nondestructive nature of the XCT allowed us to preserve the lunar dust particles, while its 3-D nature allowed us to extract meaningful microstructural information inaccessible via traditional 2-D characterization techniques. The multimodal correlative analysis further allowed us to identify the compositional and microstructural features of the agglutinate. These observations were linked to the formation process of the agglutinate to inform a hypothesis on the dynamic formation sequence of lunar regolith.
月球凝集物样本的微观结构表征在月球科学和宇宙化学领域有许多重要用途,从了解月球碎屑的形成过程到为人类在月球上的活动做好准备。在这项研究中,采用了先进的相关表征方法来研究从阿波罗 11 号任务中获取的月球凝集物颗粒的微观结构。多模态表征工作以三维 X 射线计算机断层扫描(XCT)为中心,并辅以二维技术,包括扫描电子显微镜和能量色散 X 射线光谱。XCT 的无损特性使我们能够保存月球尘埃颗粒,而其三维特性又使我们能够提取传统二维表征技术无法获取的有意义的微观结构信息。多模态相关分析使我们能够进一步确定凝集物的成分和微观结构特征。我们将这些观察结果与凝集物的形成过程联系起来,从而提出了月球碎屑岩动态形成序列的假设。
{"title":"Advanced microstructural and compositional analysis of a lunar agglutinate from the Apollo 11 mission","authors":"Tai-Jan Huang, Eshan Ganju, Hamid Torbatisarraf, Michelle S. Thompson, Nikhilesh Chawla","doi":"10.1111/maps.14157","DOIUrl":"10.1111/maps.14157","url":null,"abstract":"<p>The microstructural characterization of lunar agglutinate samples serves many essential purposes in lunar science and cosmochemistry, from understanding the formation process of lunar regolith to preparing for human activity on the Moon. In this study, an advanced correlative characterization methodology was employed to examine the microstructure of a lunar agglutinate particle retrieved from the Apollo 11 mission. The multimodal characterization efforts were centered around 3-D x-ray computed tomography (XCT) and were complemented by 2-D techniques, including scanning electron microscopy and energy-dispersive x-ray spectroscopy. The nondestructive nature of the XCT allowed us to preserve the lunar dust particles, while its 3-D nature allowed us to extract meaningful microstructural information inaccessible via traditional 2-D characterization techniques. The multimodal correlative analysis further allowed us to identify the compositional and microstructural features of the agglutinate. These observations were linked to the formation process of the agglutinate to inform a hypothesis on the dynamic formation sequence of lunar regolith.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 6","pages":"1455-1472"},"PeriodicalIF":2.2,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.14157","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140234664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The use of meteoritic iron in the manufacture of human artifacts since the Bronze Age has been well documented, including the iron blade of Tutankhamun's dagger. Whereas the preservation of textures and mineral inclusions suggest relatively low temperature (<950°C) working of meteoritic metal used in artifacts, higher temperature working—that is, forging—could have occurred, based on studies of Bronze Age slag. The extent to which the forging of meteoritic iron might change the bulk composition, especially the trace elements used for classification of iron meteorites, is largely unknown. Using electron microbeam methods (SEM and EPMA), and trace element analysis (ICP-MS), we analyze metal obtained at different stages during the modern forging of a set of knife blades from fragments of the Gebel Kamil meteorite, and assess the degree to which bulk element composition, mineral inclusions, and textures are modified. We find that while forging does destroy the original texture and removes mineral inclusions, it does not significantly modify the trace elements typically used in iron meteorite classification, at least for the relatively Ni-rich composition represented by Gebel Kamil. While we acknowledge that the modern method by which the knife blades were forged from Gebel Kamil would not have occurred in the Bronze Age, our results represent an upper temperature limit relative to the inferred conditions used in ancient forging. The identification of the meteorite (if still in existence) that was used for artifacts is feasible, based on our results and current literature on ancient meteoritic artifacts.
{"title":"Does the composition of meteoritic metal change with forging? An experimental study","authors":"Mendy M. Ouzillou, Christopher D. K. Herd","doi":"10.1111/maps.14160","DOIUrl":"10.1111/maps.14160","url":null,"abstract":"<p>The use of meteoritic iron in the manufacture of human artifacts since the Bronze Age has been well documented, including the iron blade of Tutankhamun's dagger. Whereas the preservation of textures and mineral inclusions suggest relatively low temperature (<950°C) working of meteoritic metal used in artifacts, higher temperature working—that is, forging—could have occurred, based on studies of Bronze Age slag. The extent to which the forging of meteoritic iron might change the bulk composition, especially the trace elements used for classification of iron meteorites, is largely unknown. Using electron microbeam methods (SEM and EPMA), and trace element analysis (ICP-MS), we analyze metal obtained at different stages during the modern forging of a set of knife blades from fragments of the Gebel Kamil meteorite, and assess the degree to which bulk element composition, mineral inclusions, and textures are modified. We find that while forging does destroy the original texture and removes mineral inclusions, it does not significantly modify the trace elements typically used in iron meteorite classification, at least for the relatively Ni-rich composition represented by Gebel Kamil. While we acknowledge that the modern method by which the knife blades were forged from Gebel Kamil would not have occurred in the Bronze Age, our results represent an upper temperature limit relative to the inferred conditions used in ancient forging. The identification of the meteorite (if still in existence) that was used for artifacts is feasible, based on our results and current literature on ancient meteoritic artifacts.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 6","pages":"1495-1505"},"PeriodicalIF":2.2,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.14160","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140234769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Amanda Ostwald, Arya Udry, James M. D. Day, Juliane Gross
Nakhlite and chassignite meteorites are cumulate rocks thought to originate from the same location on Mars. Petrogenetic relationships between nakhlites and chassignites are not fully constrained, and the two cumulus phases in nakhlites—olivine and clinopyroxene—possibly formed either together from one magma or separately from different magmas. Primary magma compositions can potentially be determined from studies of melt inclusions (MIs) trapped within early-formed mineral phases. MIs frequently undergo post-entrapment effects, and when such processes occur, there can be significant changes to their compositions. Here, we report major, minor, and trace element abundances for MIs in cumulus phases in nakhlites and chassignites. The melt compositions that they record are variable (MgO = 2.50–13.5 wt%, K2O = 0.03–3.03 wt%, La/Yb = 2.46%–16.4%) and are likely affected by diffusive reequilibration with changing magma composition outside of their host phases. Evidence for diffusive reequilibration suggests that nakhlite and chassignite magmas were generated in an open system, and cumulus phases may have undergone magma storage and mixing. Such processes may be akin to those that occur in terrestrial intrusive magmatic systems by open-system magma recharge. MIs within the nakhlite and chassignite suite therefore provide insights into magmatic processes during magma storage and transit on Mars.
{"title":"Melt inclusion heterogeneity in nakhlite and chassignite meteorites and evidence for complicated, multigenerational magmas","authors":"Amanda Ostwald, Arya Udry, James M. D. Day, Juliane Gross","doi":"10.1111/maps.14159","DOIUrl":"10.1111/maps.14159","url":null,"abstract":"<p>Nakhlite and chassignite meteorites are cumulate rocks thought to originate from the same location on Mars. Petrogenetic relationships between nakhlites and chassignites are not fully constrained, and the two cumulus phases in nakhlites—olivine and clinopyroxene—possibly formed either together from one magma or separately from different magmas. Primary magma compositions can potentially be determined from studies of melt inclusions (MIs) trapped within early-formed mineral phases. MIs frequently undergo post-entrapment effects, and when such processes occur, there can be significant changes to their compositions. Here, we report major, minor, and trace element abundances for MIs in cumulus phases in nakhlites and chassignites. The melt compositions that they record are variable (MgO = 2.50–13.5 wt%, K<sub>2</sub>O = 0.03–3.03 wt%, La/Yb = 2.46%–16.4%) and are likely affected by diffusive reequilibration with changing magma composition outside of their host phases. Evidence for diffusive reequilibration suggests that nakhlite and chassignite magmas were generated in an open system, and cumulus phases may have undergone magma storage and mixing. Such processes may be akin to those that occur in terrestrial intrusive magmatic systems by open-system magma recharge. MIs within the nakhlite and chassignite suite therefore provide insights into magmatic processes during magma storage and transit on Mars.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 6","pages":"1473-1494"},"PeriodicalIF":2.2,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140233952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Introduction to this issue which is in memory of Edward R. D. Scott (1947–2021)","authors":"Ian Sanders","doi":"10.1111/maps.14154","DOIUrl":"10.1111/maps.14154","url":null,"abstract":"","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 4","pages":"629"},"PeriodicalIF":2.2,"publicationDate":"2024-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140241207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Andrea Patzer, Julia Kowalski, Tommaso Di Rocco, Andreas Pack
The ureilite parent body (UPB) was, in all likelihood, completely broken apart when hit by another object early in its history and reassembled into daughter bodies. We here present a study tailored to constrain the dimensions of the impact debris produced in the catastrophic disruption. Using a customized Python code to simulate the thermal evolution of the UPB fragments, we compared the FeO profiles modeled for different depths within those fragments with those measured across the reduction rims in olivines of 12 different ureilites (n = 37). Our profile data were fitted to the theoretical cooling profiles determined with a transient thermal model. The results are coherent and consistent with earlier studies and, despite using simplified boundary conditions (fragments described as ideal spheres and maximum radiation), our data provide valuable context on possible cooling pathways of the UPB debris. In detail, we found that the average depths within the given fragments from which our samples of ureilites originated were limited to 0.3–0.4 ± 0.1 m, with only few exceptions (e.g., one highly reduced sample lacked suitable reduction profiles suggesting either a depth of origin of >2 m or shielding of this fragment from rapid cooling, e.g., due to hovering in the center of a relatively dense cloud of debris). In addition, we calculated that the cooling from 1473 to 1100 K of the average fragment at the depth of our samples took no more than 3–4 days, suggesting that the reassembly of the ureilite daughter bodies could have been a very fast process.
ureilite母体(UPB)很可能在其历史早期被另一个天体撞击时完全碎裂,然后重新组装成子体。我们在此介绍一项研究,旨在确定灾难性破坏过程中产生的撞击碎片的尺寸。我们使用定制的Python代码来模拟UPB碎片的热演化,并将这些碎片内部不同深度的氧化铁剖面与在12个不同脲榴石(n = 37)橄榄石的还原边缘测量到的氧化铁剖面进行了比较。我们的剖面数据与通过瞬态热模型确定的理论冷却剖面进行了拟合。尽管使用了简化的边界条件(碎片被描述为理想球体和最大辐射),我们的数据还是为 UPB 碎片可能的冷却路径提供了有价值的背景资料。具体而言,我们发现,我们的尿锂石样本所来自的特定碎片的平均深度仅限于 0.3-0.4 ± 0.1 米,只有少数例外(例如,一个高度还原的样本缺乏合适的还原剖面,这表明其起源深度大于 2 米,或者由于悬停在相对密集的碎片云中心等原因,该碎片受到了快速冷却的屏蔽)。此外,根据我们的计算,在我们的样本深度,平均碎片从 1473 K 冷却到 1100 K 的时间不超过 3-4 天,这表明脲石子体的重新组合可能是一个非常快速的过程。
{"title":"The catastrophic break-up of the ureilite parent body: Modeling constraints on the debris size","authors":"Andrea Patzer, Julia Kowalski, Tommaso Di Rocco, Andreas Pack","doi":"10.1111/maps.14155","DOIUrl":"10.1111/maps.14155","url":null,"abstract":"<p>The ureilite parent body (UPB) was, in all likelihood, completely broken apart when hit by another object early in its history and reassembled into daughter bodies. We here present a study tailored to constrain the dimensions of the impact debris produced in the catastrophic disruption. Using a customized Python code to simulate the thermal evolution of the UPB fragments, we compared the FeO profiles modeled for different depths within those fragments with those measured across the reduction rims in olivines of 12 different ureilites (<i>n</i> = 37). Our profile data were fitted to the theoretical cooling profiles determined with a transient thermal model. The results are coherent and consistent with earlier studies and, despite using simplified boundary conditions (fragments described as ideal spheres and maximum radiation), our data provide valuable context on possible cooling pathways of the UPB debris. In detail, we found that the average depths within the given fragments from which our samples of ureilites originated were limited to 0.3–0.4 ± 0.1 m, with only few exceptions (e.g., one highly reduced sample lacked suitable reduction profiles suggesting either a depth of origin of >2 m or shielding of this fragment from rapid cooling, e.g., due to hovering in the center of a relatively dense cloud of debris). In addition, we calculated that the cooling from 1473 to 1100 K of the average fragment at the depth of our samples took no more than 3–4 days, suggesting that the reassembly of the ureilite daughter bodies could have been a very fast process.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 6","pages":"1407-1420"},"PeriodicalIF":2.2,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.14155","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140248828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In differentiated planetesimals, the liquid core starts to crystallize during secular cooling, followed by the separation of liquid–solid phases in the core. The wetting property between liquid and solid iron alloys determines whether the core melts are trapped in the solid core or they can separate from the solid core during core crystallization. In this study, we performed high-pressure experiments under the conditions of the interior of small bodies (0.5–3.0 GPa) to study the wetting property (dihedral angle) between solid Fe and liquid Fe-S as a function of pressure and duration. The measured dihedral angles are approximately constant after 2 h and decrease with increasing pressure. The dihedral angles range from 30° to 48°, which are below the percolation threshold of 60° at 0.5–3.0 GPa. The oxygen content in the melt decreases with increasing pressure and there are strong positive correlations between the S + O or O content and the dihedral angle. Therefore, the change in the dihedral angle is likely controlled by the O content of the Fe-S melt, and the dihedral angle tends to decrease with decreasing O content in the Fe-S melt. Consequently, the Fe-S melt can form interconnected networks in the solid core. In the obtained range of the dihedral angle, a certain amount of the Fe-S melt can stably coexist with solid Fe, which would correspond to the “trapped melt” in iron meteorites. Excess amounts of the melt would migrate from the solid core over a long period of core crystallization in planetesimals.
在分化的类地行星中,液态内核在世俗冷却过程中开始结晶,随后内核中的液固相分离。液态和固态铁合金之间的润湿特性决定了核心熔体是被困在固态核心中,还是能在核心结晶过程中从固态核心中分离出来。在这项研究中,我们在小天体内部(0.5-3.0 GPa)的条件下进行了高压实验,以研究固体铁和液体 Fe-S 之间的润湿性(二面角)与压力和持续时间的函数关系。测得的二面角在 2 小时后大致保持不变,并随着压力的增加而减小。二面角的范围在 30° 至 48° 之间,低于 0.5-3.0 GPa 下 60° 的渗流阈值。熔体中的氧含量随着压力的增加而降低,S + O 或 O 含量与二面角之间存在很强的正相关性。因此,二面角的变化很可能是由 Fe-S 熔体中的 O 含量控制的,二面角往往随着 Fe-S 熔体中 O 含量的降低而减小。因此,Fe-S 熔体可在固体内核中形成相互连接的网络。在得到的二面角范围内,一定量的Fe-S熔体可以与固体铁稳定共存,这就相当于铁陨石中的 "被困熔体"。过量的熔体会在行星体中长期的内核结晶过程中从固体内核中迁移出来。
{"title":"Wetting property of Fe-S melt in solid core: Implication for the core crystallization process in planetesimals","authors":"Shiori Matsubara, Hidenori Terasaki, Takashi Yoshino, Satoru Urakawa, Daisuke Yumitori","doi":"10.1111/maps.14149","DOIUrl":"10.1111/maps.14149","url":null,"abstract":"<p>In differentiated planetesimals, the liquid core starts to crystallize during secular cooling, followed by the separation of liquid–solid phases in the core. The wetting property between liquid and solid iron alloys determines whether the core melts are trapped in the solid core or they can separate from the solid core during core crystallization. In this study, we performed high-pressure experiments under the conditions of the interior of small bodies (0.5–3.0 GPa) to study the wetting property (dihedral angle) between solid Fe and liquid Fe-S as a function of pressure and duration. The measured dihedral angles are approximately constant after 2 h and decrease with increasing pressure. The dihedral angles range from 30° to 48°, which are below the percolation threshold of 60° at 0.5–3.0 GPa. The oxygen content in the melt decreases with increasing pressure and there are strong positive correlations between the S + O or O content and the dihedral angle. Therefore, the change in the dihedral angle is likely controlled by the O content of the Fe-S melt, and the dihedral angle tends to decrease with decreasing O content in the Fe-S melt. Consequently, the Fe-S melt can form interconnected networks in the solid core. In the obtained range of the dihedral angle, a certain amount of the Fe-S melt can stably coexist with solid Fe, which would correspond to the “trapped melt” in iron meteorites. Excess amounts of the melt would migrate from the solid core over a long period of core crystallization in planetesimals.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 6","pages":"1314-1328"},"PeriodicalIF":2.2,"publicationDate":"2024-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140255444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}