¹K. D. Litasov, ²D. S. Ponomarev, ¹I. S. Bazhan, ³A. Ishikawa, ⁴N. M. Podgornykh, ¹N. P. Pokhilenko
Doklady Earth Sciences 478, 79-81 Link to Article [https://doi.org/10.1134/S1028334X18010154]
¹Sobolev Institute of Geology and Mineralogy, Siberian BranchRussian Academy of Sciences, Novosibirsk, Russia
²Novosibirsk State University Novosibirsk, Russia
³Tokyo University, Tokyo, Japan
⁴Siberian Central Geological Museum, Novosibirsk, Russia

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¹K. D. Litasov, ³A. Ishikawa, ¹I. S. Bazhan, ²D. S. Ponomarev, ³T. Hirata, ⁴N. M. Podgornykh, ¹N. P. Pokhilenko
Doklady Earth Sciences 478, 62-66 Link to Article [https://doi.org/10.1134/S1028334X18010063]
¹Sobolev Institute of Geology and Mineralogy, Siberian Branch Russian Academy of Sciences, Novosibirsk, Russia
²Novosibirsk State University, Novosibirsk, Russia
³University of Tokyo, Tok, yoJapan
⁴Central Siberian Geological Museum, Novosibirsk, Russia

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¹T. A. Gornostaeva,¹ A. V. Mokhov, ¹P. M. Kartashov, ¹O. A. Bogatikov
Doklady Earth Sciences 478, 204-207 Link to Article [https://doi.org/10.1134/S1028334X18020034]
¹Institute of Geology of Ore Deposits, Petrography, Mineralogy, and Geochemistry Russian Academy of Sciences, Moscow, Russia

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¹Masakuni Yamanobe, ¹Tomoki Nakamura, ¹Daisuke Nakashima
Polar Science 15, 29-38 Link to Article [https://doi.org/10.1016/j.polar.2017.12.002]
¹Division of Earth and Planetary Materials Science, Tohoku University, Miyagi 980-8578, Japan

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¹M.Kimura, ^1,2N.Imae, ^1,2A.Yamaguchi,¹H.Haramura, ¹H.Kojima
Polar Science 15, 24-28 Link to Article [https://doi.org/10.1016/j.polar.2017.12.001]
¹National Institute of Polar Research, Tokyo 190-8518, Japan
²Department of Polar Science, School of Multidisciplinary Science, SOKENDAI (The Graduate University for Advanced Studies), Tokyo 190-8518, Japan

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¹Kaori Jogo,²Motoo Ito, ³Tomoki Nakamura, ²Sachio Kobayashi, ⁴Jong Ik Lee
Earth, Planets and Space 70, 37 Link to Article [https://doi.org/10.1186/s40623-018-0809-5]
¹Division of Earth-System Polar Research Institute, Incheon South Korea
²Kochi Institute for Core Sample Research, JAMSTEC Nankoku Japan
³Division of Earth and Planetary Materials Science Tohoku University Sendai Japan
⁴Unit of Antarctic K-route Expeditio nKorea Polar Research Institute Incheon South Korea

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¹S. A. Prevec,¹S. H. Büttner
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13076]
¹Department of Geology, Rhodes University, Grahamstown, South Africa
Published by arrangement with John Wiley & Sons

The offset dykes of the Sudbury Igneous Complex comprise two distinct main magmatic facies, a high‐temperature inclusion‐free quartz diorite (QD), and a subsequently intruded lower temperature, mineralized, and inclusion‐rich quartz diorite (MIQD). The MIQD facies was emplaced after QD dykes had solidified. Key controlling factors of the two injection phases were (1) the development of a coherent roof, which confined the melt sheet; and (2) the periodic increase of melt and fluid pressure within the melt sheet. For the injection of QD melt, the melt pressure exceeded the normal stress acting on fracture surfaces. For the later refracturing of QD dykes and the injection of MIQD melt, the melt pressure increased further, exceeding the tensile strength of, and the normal stress acting on, QD dykes. We associate the melt pressure increase required for both injection episodes with degassing and devolatilization of cooling melt close to the roof. Within the hydraulically connected melt column, the related pressure increase was transmitted to the base of the melt sheet where QD and MIQD melt was extracted into dykes. Residual core to rim thermal gradients in the QD dykes produced tensile strength gradients, accounting for the typically central location of MIQD dykes within QD dykes.

¹Ronald T. Daly, ¹Peter H. Schultz
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13081]
¹Department of Earth, Environmental and Planetary Sciences, Brown University, , Providence, Rhode Island, USA
Published by arrangement with John Wiley & Sons

Impact angle plays a significant role in determining the fate of the projectile. In this study, we use a suite of hypervelocity impact experiments to reveal how impact angle affects the preservation, distribution, and physical state of projectile residues in impact craters. Diverse types of projectiles, including amorphous silicates, crystalline silicates, and aluminum, in two sizes (6.35 and 12.7 mm), were launched into blocks of copper or 6061 aluminum at speeds between 1.9 and 5.7 km s−1. Crater interiors preserve projectile residues in all cases, including conditions relevant to the asteroid belt. These residues consist of projectile fragments or projectile‐rich glasses, depending on impact conditions. During oblique impacts at 30° and 45°, the uprange crater wall preserves crystalline fragments of the projectile. The fragments of water‐rich projectiles such as antigorite remain hydrated. Several factors contribute to enhanced preservation on the uprange wall, including a weaker shock uprange, uprange acceleration as the shock reflects off the back of the projectile, and rapid quenching of melts along the projectile–target interface. These findings have two broader implications. First, the results suggest a new collection strategy for flyby sample return missions. Second, these results predict that the M‐type asteroid Psyche should bear exogenic, impactor‐derived debris.

¹Yasuhito Sekine,²Kenya Kodama,³Takamichi Kobayashi,²Seiji Obata,¹Yu Chang,⁴Nanako O. Ogawa,⁴Yoshinori Takano,⁴Naohiko Ohkouchi,²Koichiro Saiki,⁵Toshimori Sekine
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13075]
¹Department of Earth and Planetary Science, The University of Tokyo, , Bunkyo, Tokyo, Japan
²Department of Complexity Science and Engineering, The University of Tokyo, Kashiwa, Chiba, Japan
³National Institute for Materials Science, Tsukuba, Ibaraki, Japan
⁴Department of Biogeochemistry, JAMSTEC, Yokosuka, Kanagawa, Japan
⁵Center for High Pressure Science and Technology Advanced Research, , Shanghai, China
Published by arrangement with John Wiley & Sons

The present study systematically investigates shock‐induced alteration of organic simulants of planetary bodies (OSPBs) as a function of peak shock pressure and temperature by impact experiments. Our results show that the composition and structure of OSPBs are unchanged upon impacts at peak pressures ≤~5 GPa and temperatures ≤~350 °C. On the other hand, these are dramatically changed upon impacts at >7–8 GPa and > ~400 °C, through loss of hydrogen‐related bonds and concurrent carbonization, regardless of the initial compositions of OSPBs. Compared with previous results on static heating of organic matter, we suggest that shock‐induced alteration cannot be distinguished from static heating only by Raman and infrared spectroscopy. Our experimental results would provide a proxy indicator for assessing degree of shock‐induced alteration of organic matter contained in carbonaceous chondrites. We suggest that a remote‐sensing signature of the 3.3–3.6 μm absorption due to hydrogen‐related bonds on the surface of small bodies would be a promising indicator for the presence of less‐thermally‐altered (i.e., <350 °C) organic matter there, which will be a target for landing to collect primordial samples in sample‐return spacecraft missions, such as Hayabusa2 and OSIRIS‐REx.

^1,2Xiaojia Zeng, ¹Shijie Li, ³Ingo Leya, ¹Shijie Wang, ³Thomas Smith, ¹Yang Li, ⁴Peng Wang
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13073]
¹Center for Lunar and Planetary Sciences, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
²University of Chinese Academy of Sciences, Beijing, China
³Physics Institute, University of Bern, , Bern, Switzerland
⁴Division of Mines and Geology, Sixth Geological Brigade, Hami, China
Published by arrangement with John Wiley & Sons

The Kumtag 016 strewn field was found in the eastern part of the Kumtag desert, Xinjiang Province, China. In this study, 24 recovered meteorites have been characterized by a suite of different analytical techniques to investigate their petrography, mineralogy, bulk trace elements, noble gas isotopic composition, density, and porosity. We attribute to the strewn field 22 L5 chondrites with shock stage S4 and weathering grade W2–W3. Two different meteorites, Kumtag 021, an L4 chondrite and Kumtag 032, an L6 chondrite, were recognized within the strewn field area. Moreover, Kumtag 003, an H5 chondrite, was previously found in the same area. We infer that the Kumtag 016 strewn field most likely consists of at least four distinct meteorite falls. The effects of terrestrial weathering on the studied meteorites involve sulfide/metal alteration, chemical changes (Sr, Ba, Pb, and U enrichments and depletion in Cr, Co, Ni, and Cs abundances), and physical modifications (decrease of grain density and porosity). Measurements of the light noble gases indicate that the analyzed Kumtag L5 samples contain solar wind‐implanted noble gases with a 20Ne/22Ne ratio of ~12.345. The cosmic‐ray exposure (CRE) ages of the L5 chondrites are in a narrow range (3.6 ± 1.4 Ma to 5.2 ± 0.4 Ma). For L4 chondrite Kumtag 021 and L6 chondrite Kumtag 032, the CRE ages are 5.9 ± 0.4 Ma and 4.7 ± 0.8 Ma, respectively.