¹Matthieu Gounelle
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13127]
¹Muséum National d’Histoire Naturelle
Published by arrangement with John Wiley & Sons

The scope of the present short report is to honor the discovery of the first calcium‐aluminum‐rich inclusion in 1968 as well as the discoverer, the French mineralogist, Mireille Christophe Michel‐Lévy.

¹Anatolii V. Fisenko,²Alexander B. Verchovsky,^3,4Andrei A. Shiryaev,¹Luba F. Semjonova,³Alexey A. Averin,⁵Alexander L. Vasiliev,^3,4Maximilian S. Nickolsky
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13130]
¹Vernadsky Institute of Geochemistry and Analytical Chemistry RAS, Moscow, Russia
²School of Physical Sciences, The Open UniversityWalton Hall, Milton Keynes, UK
³A. N. Frumkin Institute of Physical Chemistry and Electrochemistry RAS, Moscow, Russia
⁴Institute of Geology of Ore Deposits, Petrography, Mineralogy, and Geochemistry, Russian Academy of SciencesMoscow, Russia
⁵NRC “Kurchatov Institute”, Moscow, Russia
Published by arrangement with John Wiley & Sons

Acid‐resistant residues (ARR) were separated from the Saratov (L4) meteorite with the aim to shed more light on the origin of the planetary noble gases (the Q‐gases) in meteorites and the nature of their carrier phase (Q‐phase). Eleven fractions were obtained by HCl and HCl+HF etching, ultrasonication, and subsequent density separation of the ARR in isopropanol and isopropanol+NaOH. Two aliquots of the fractions were also treated with H2O2 and HNO3 to investigate any influence of the oxidizing agent on the Q‐gases retention. The separated ARR fractions have been analyzed for C, N, and noble gases using step combustion. Raman and TEM analyses of the carbonaceous phase structures have also been applied for some of the fractions. This appears to be one of the most detailed investigations of the ARR fractions so far. The important observation made for the ARR fraction studied by TEM is the presence of abundant curved graphene stacks with a variable number of layers. Significant amounts of single‐ and bilayer graphenes and nanosized chromite grains partly covered with graphene layers are also observed. The principal features of the Q noble gases in the studied ARR fractions are the following. (1) Elemental composition of the Q‐gases depends on the extraction protocol. The most interesting is that upon H2O2 oxidation, the noble gases are retained in the sequence Xe<Ar≪He, while after HNO3 it is in the sequence He≪Xe

¹Jüri Plado,²Satu Hietala,¹Timmu Kreitsmann,²Jouni Lerssi,²Jari Nenonen,³Lauri J. Pesonen
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13134]
¹Department of Geology, University of Tartu, Tartu, Estonia
²Geological Survey of Finland, Kuopio, Finland
³Solid Earth Geophysics Laboratory, Physics Department, University of Helsinki, Helsinki, Finland
Published by arrangement with John Wiley & Sons

The Summanen structure (62°39.0′N, 25°22.5′E) is located within the Paleoproterozoic Central Finland Granite Belt, Fennoscandian Shield. The structure is hidden under Lake Summanen and not directly observable. It owes its discovery to low‐altitude airborne geophysical data, which revealed a circular, ~2.6 km wide electromagnetic in‐phase, and resistivity, anomalies. Two field campaigns were conducted in 2017 to search for impact signatures. The fieldwork concentrated on the southeastern side of the lake following the ice flow direction of the latest (Weichselian) glaciation. In addition, the islands and the SE peninsulas of the mainland were investigated for outcrops and glacial erratics. A few tens of erratic boulders with shatter cones and striated features, and a few brecciated rocks were discovered. Lamposaari Island in the eastern part of the lake revealed one fractured outcrop containing in situ porphyritic granite with converging striated features. Microscopic shock metamorphic features in two shatter‐cone‐bearing samples of porphyritic granite were found. These are planar deformation features (PDFs; up to two sets) in quartz and kink bands in biotite. Based on these geological, geophysical, and petrographic results, we suggest that Lake Summanen hides a relatively small, probably simple, meteorite impact structure, the twelfth confirmed one in Finland, of so far unknown age.

^1,2Pia Friend,^2,3Dominik C. Hezel,⁴Jean‐Alix Barrat,⁵Jutta Zipfel,⁵Herbert Palme,⁶Knut Metzler
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13139]
¹Fachbereich C – Physik, Bergische Universität Wuppertal, Wuppertal, Germany
²Department of Geology and Mineralogy, University of Cologne, Köln, Germany
³Department of Mineralogy, Natural History Museum, London, UK
⁴Institut Universitaire Européen de la Mer, Université de Bretagne Occidentale, CNRS UMR 6538, Plouzané, France
⁵Forschungsinstitut und Naturmuseum Senckenberg, Frankfurt am Main, Germany
⁶Institut für Planetologie, Universität Münster, Münster, Germany
Published by arrangements with John Wiley & Sons

Jbilet Winselwan (JW) is a recently found CM2 chondrite breccia containing two lithologies. A study of 508 chondrules provides the first statistically reliable size distribution for CM chondrite chondrules, which is about log normal with a mean chondrule size of 149 μm (lithology I) and 141 μm (lithology II). Chondrules are surrounded by fine‐grained rims. Apparent chondrule diameters and their apparent rim thicknesses are positively correlated with slopes of 0.12 (lithology II) and 0.18 (lithology I), the latter typical of CM chondrites. The CM chondrites are generally primitive and parts of JW experienced only mild aqueous alteration. Bulk JW element ratios are solar (=CI chondritic), e.g., Si/Mg (1.12), Fe/Mg (1.80–1.83), Ti/Al (0.053), and about solar for Ca/Al. The 26 chemically studied chondrules have subchondritic Si/Mg (0.88) and Fe/Mg ratios (0.21). Matrix and the fine‐grained chondrule rims on the other hand have superchondritic Si/Mg ratios with means of 1.34 and 1.41, respectively. The Fe/Mg ratios are also superchondritic, with means of 2.41 (matrix) and 2.61 (fine‐grained rims). The refractory element ratios in chondrules are superchondritic (Ti/Al: 0.106; Ca/Al: 1.64), and subchondritic in the JW matrix (Ti/Al: 0.031; Ca/Al: 0.71) and in the fine‐grained rims (Ti/Al: 0.023; Ca/Al: 0.68). These complementary element ratios require formation of chondrules and matrix/rims from the same reservoir in order to obtain a chondritic bulk composition. Most chondrules are mineralogically zoned, with olivine in the core and low‐Ca pyroxene in the rim; hence, CM chondrules were open systems, exchanging material with the surrounding gas.