The chondrite host, impact melt and a 2.5 cm-sized achondritic inclusion of the Tsarev L5 chondrite were investigated in order to reconstruct the formation, thermal and shock history of the L chondrite parent body. Tsarev is a quickly cooled impact melt breccia experienced a late impact metamorphism and metasomatism. The impact melt is similar by mineral composition to the host chondrite. The elliptic achondritic inclusion was likely formed as a molten drop floating in open space at zero gravity and shares many features with so-called macrochondrules and porphyritic fragments in ordinary chondrites those have OC chemistry but are depleted in metal and sulfide. The inclusion differs from both of these object groups in its larger grain size, average Ca abundance of feldspar, heterogeneous internal texture, and unusually enrichment in Ca-phosphates of four generations. The inclusion is different by texture and composition from other achondritic inclusions described in Tsarev and is suggested to be re-melted little-fractionated phosphate-rich rock formed on the L chondrite asteroid as a result of one more ancient melting process and several fluid activity episodes on the parent body before its incorporation with the host chondrite material. After the breccia-forming impact resulted in the chondrite lithification subsequent shock and fluid injection affected the Tsarev chondrite. A diverse of the achondritic inclusions and a number of processes indicate a multistage prolonged evolution of the L chondrite parent body.

We performed high-resolution Ar-40/Ar-39 dating of a suite of lunar meteorites from hot deserts: Dhofar 025, 309, 730, 733, 1442, Northwest Africa 6888, and Sayh al Uhaymir 449. The identification of terrestrial and lunar trapped argon components via isochrons allowed us to identify in situ radiogenic argon and to obtain proper chronological information. The last total reset ages of all studied samples are in the range of 3.1 to 4.2 Ga, coeval with the intense cratering period on the Moon and mare volcanism. Only Northwest Africa 6888 was totally reset <2.5 Ga ago. The most deeply buried breccia Dhofar 733 has the oldest age of 4.23 +/- 0.04 Ga within this series of meteorites. Dhofar 733, 1442, and NWA 6888 were furthermore affected by recent impact events <= 1 Ga. All meteorites were irradiated by galactic cosmic rays on the surface of the Moon for several up to hundreds of Ma. A simple irradiation history is revealed for only one meteorite Dhofar 733 delivered to Earth within similar to 0.5 Ma. The comparison of exposure ages, solar argon abundances and partial loss of cosmogenic and radiogenic argon of lunar breccias indicates that long surface residence enhances accumulation of solar wind implanted Ar-36 but also diffusive gas loss, most likely by surface thermal effects as solar and/or impact heating. The surficial regolith breccias Dhofar 025, 1442, NWA 6888, SaU 449 contain lunar trapped argon with Ar-40/Ar-36 ratios varying from 6 to 15, while the deep-derived breccia Dhofar 730 contains argon with (Ar-40/Ar-36)(trapped) ratio of 81. This could indicate that the composition of trapped argon in lunar meteorites may depend on rock layering depth. We suggest that the final capture of gases happens during sintering and agglutination along grain boundaries caused by thermal processes accompanying shock-induced compaction. Dhofar 1442 contains two distinct lunar trapped argon components with (Ar-40/Ar-36)(trapped) ratios of 14.58 +/- 0.28 and 5.5 +/- 0.7 indicating that lunar meteorites may contain more than one extraterrestrial trapped component incorporated during different thermal events. Our new Ar-40/Ar-39 ages of lunar meteorites significantly increase the number of high- resolution plateau age spectra, providing more compelling evidence of geochronologically meaningful pre 3.9 Ga ages. The different age distribution when compared to Apollo samples that were frequently dominated by Imbrium ejecta may be related to the fact that lunar meteorites provide a more random and thus complete sampling of the lunar surface, encompassing ejecta of older large basins, thereby favoring scenarios of more continuous or episodic pre 3.9 Ga bombardments. A possible scenario leading to episodic small body disturbances and bombardments involves close stellar encounters within the massive stellar cluster in which the sun resided during the first hundreds of million years of its lifetime.

Изучена дегазация вещества углистого хондрита Murchison (тип СМ2) на специально сконструированной для этих задач установке. Представлены результаты экспериментальных исследований по ступенчатому нагреву (без накопления газов) и изотермическому отжигу образцов метеорита с определением состава выделяемых газов методами газовой хроматографии в интервале температур от 200 до 800°C. Для учета сорбированной воды дополнительно изучена дегазация при 50 и 110°C. Получены ИК-спектры метеорита Murchison после отжига при разных температурах, и на их основе прослежен ход тепловой деструкции. Проведено сравнение с результатами дегазации обыкновенного хондрита Челябинск (тип LL5) и показано существенное увеличение выделения углеродсодержащих газов для метеорита Murchison.

Metal‐rich carbonaceous CB chondrites are generally assumed to be materials accreted from the gas–dust plume formed in catastrophic collisions of planetesimals, at least one of which was differentiated into a metal core and silicate shell. Micron‐sized inclusions of siliceous alkali‐rich glasses associated with sulfides were found in the metal globules of the Sierra Gorda 013 (SG 013), a CBa‐like chondrite. These inclusions are unusual carriers of volatile alkalis which are commonly depleted in CB chondrites. The inclusions are presented by two types: (1) Al‐bearing Nb‐poor glass associated with daubréelite and (2) Nb‐bearing Ca,Al,Mg‐poor glass associated with an unknown Na‐bearing Cr‐sulfide. The glass compositions do not correspond to equilibrium condensation, evaporation, or melting. The Nb‐bearing glass has a superchondritic Nb/Ta ratio (31) most likely indicating the fractionation of Nb and Ta in the high‐temperature gas–dust impact plume due to condensation from vapor or evaporation of precursor Nb‐rich particles. The glasses are interpreted as reaction products between refractory plume condensate particles (or possibly planetary or chondritic solids) with relatively low‐temperature K‐Na‐Si‐rich gas in oxidized conditions, possibly in a common plume vapor reservoir. Compositional differences indicate that the glasses and sulfides originated from several different sources under different fO 2 , fS 2 , and T conditions and were likely combined together and transported to the metal globule formation region by material flows in the heterogeneous impact plume. The glass–sulfide particles were enclosed in the globules aggregated from smaller solid or molten metal grains. The metal globules were further melted during transport to the high‐temperature plume region or by plume shockwave heating. Thus, the composition of the glasses, the host metal, and the main mass of SG 013 shows dynamic heterogeneity of physical conditions and impact plume composition after a large‐scale planetesimal collision.

The degassing of Allende carbonaceous chondrite (CV3 type) was studied using a setup specially designed for this purpose. The experiments involved stepwise heating (without gas accumulation) and isothermal annealing of meteorite samples with the composition of released gases determined through gas chromatography methods in the temperature range from 200 to 800°C. To account for sorbed water, degassing at 50 and 110°C was additionally analyzed. The Raman and IR spectra of both the primary Allende substance and the substance after its annealing at three temperatures (200, 500, and 800°C) were obtained. These spectra were used to trace the thermal transformation of the substance of the meteorite’s parent body and estimate the maximum temperature of metamorphism. The results were compared with the degassing of the Murchison carbonaceous chondrite of another type (CM2).

Stepwise crushing and combustion methods were applied to study the KREEP-rich lunar breccia Dhofar 1442, the clastic material of which is cemented by porous matrix. The stepwise crushing released significant amount of gases of extraterrestrial origin from gas voids. Argon, nitrogen, and carbon are simultaneously released by stepwise combustion at 1100°С. The simultaneous high-temperature degassing of these gases, as well as the coincidence of С/N ratio and nitrogen and carbon contents in high-temperature combustion steps with those of crushing indicate that the gas carriers are voids in high-temperature phases (in particular, minerals, glasses), which are decomposed/melted at these temperatures. Helium and neon are released from the same positions at lower temperatures. The isotopic composition of neon obtained by stepwise combustion and crushing corresponds to the composition of fractionated solar wind. The fraction of argon in the first crushing steps is higher than that of any other of studied gases. The 40 Ar/ 36 Ar in the trapped lunar argon is ~18, which is not consistent with empirical model implying that 40 Аr is implanted from lunar atmosphere (McKay et al., 1986; Eugster et al., 2001; Joy et al., 2011). We believe that the entrapment of volatile elements in gas voids of the meteorite Dhofar 1442 was caused by the redistribution of gases from one structural sites into others during impact events that accompanied the cratering, in particular, leading to the formation of the impact melt breccia Dhofar 1442. The trapped gases of the meteorite Dhofar 1442 contain not only typical volatile components (solar, radiogenic, cosmogenic, re-implanted 40 Ar) of lunar breccias, but also nitrogen and carbon formed through the oxidation of organic matter of metamorphosed chondrites, which are present in the breccia. With increasing number of strokes and, correspondingly, a degree of crushing, the elemental ratios change. A slight decrease of 4 He/ 20 Ne ratio during crushing is likely related to the different diffusion ability and permeability of helium relative to neon under temperature influence and/or to the heterogeneous distribution of these gases in voids of different size. The 4 He/ 36 Ar, 20 Ne/ 36 Ar, 14 N/ 36 Ar, and 12 С/ 36 Ar ratios increase by factors of 10–100 during crushing. This can be explained by the combination of dynamically different processes leading to the argon fractionation relative to other gases and uneven redistribution of gases from different positions in voids of different sizes during impact metamorphism.

The peculiarities of the composition and internal structure of chondrite NWA 12370, petrological type H5 S1 W1, were studied by means of Raman spectroscopy, XRF, and electronic sounding. The dependence of the mechanical properties of chondrite on the external hydrostatic pressure was studied by means of ultrasonic waves and static methods. This meteorite is a fragment of stone rain from the debris of the inner part of a large asteroid, about 200 km in size. We compared the mechanical characteristics obtained with those of the well-studied Pultusk chondrite of the same type, impact breccia H4/H5 S2 W1. At the early stage of the Solar System, such planetesimals made a significant contribution to the geochemical evolution of the terrestrial planets. Therefore, understanding the peculiarities of the relationship between the H chondrite’s internal structure and elastic properties is essential for assessing their contribution to the crust and upper mantle composition of the Earth and Moon and clarifying the conditions for the formation of the redox potential of the planetary interior.

The lunar meteorite Dhofar 1436 is dominated by solar wind type noble gases. Solar argon is equilibrated with “parentless” 40 Ar commonly known as lunar orphan argon. Ar‐Ar isochron analyses determined the lunar trapped 40 Ar/ 36 Ar ratio to 2.51 ± 0.04, yielding a corrected plateau age of 4.1 ± 0.1 Ga, consistent with the lunar Late Heavy Bombardment period. Lunar trapped and radiogenic argon components are all released at high temperatures (1200–1400 °C). Surprisingly, solar noble gases and lunar trapped argon can largely be released by crushing. Initial crushing steps mainly release elementally fractionated solar wind gases, while in advanced crushing steps, cosmogenic components dominate. Cosmogenic noble gases indicate irradiation at the lunar surface; they are less fractionated than solar wind species. We favor a scenario in which both solar and a large fraction of cosmogenic gases were acquired before the 4.1 Ga event, which caused shock metamorphism and formation of the regolith breccia. Sintering and agglutination along grain boundaries resulted in mobilization of solar wind, reimplanted, radiogenic, and cosmogenic noble gases, and resulted in their partial homogenization, fractionation, and retrapping in voids and/or defects accessible by crushing. An alternative scenario would be complete reset of the K‐Ar system 4.1 Ga ago accompanied by loss of all previously accumulated solar and cosmogenic noble gases. Later, the precursor of Dhofar 1436 became lunar regolith and accumulated solar and cosmogenic noble gases and reimplanted 40 Ar before its final formation of the polymict impact breccia. The C abundance of the step‐combusted Dhofar 1436 is 555.3 ppm, with δ 13 C of −28‰ to +11‰. Nitrogen contents released by crushing and combustion are 3.2 ppm and 20.8 ppm, respectively. The lightest nitrogen composition (δ 15 N = −79‰) is likely due to release from voids of shock metamorphic phases and is rather a result of the mobilization of nitrogen components that accumulated prior to the 4.1 Ga event.

The isotopic composition of noble gases, nitrogen, and carbon in two samples of the Ozerki L chondrite, which differ in the degree of impact metamorphism, analyzed by the methods of stepwise oxidation and crushing, is reported. The data obtained indicate that the meteorite contains gases trapped on the asteroid during the impact events. The isotopic composition of trapped argon, studied by the stepwise crushing method, is dominated by radiogenic 40Ar (the average 40Ar/36Ar values are 846 in the chondrite material and 1908 in the melt with fine chondrite fragments). Most of the trapped 36Ar is located in positions inaccessible for crushing. The isotopic composition of Ne is a mixture of the solar-wind neon, cosmogenic, and most likely planetary (Q) components. The elemental composition of the trapped noble gases is formed by mixing of the solar, planetary (Q), and cosmogenic components in different proportions. Diffusion processes caused by impact events most likely influenced the elemental abundance of noble gases, primarily helium. Almost all carbon and nitrogen are chemically bound in the rock. In general, their isotopic composition corresponds to that of ordinary chondrites; however, an atypically light carbon isotopic composition with a bulk value δ13C = –47.6 ± 4.8 (‰) was detected in a sample of the chondrite material. The nitrogen released during crushing is isotopically lighter than that released during oxidation. This may indicate that in the course of impact processes, solar nitrogen is more easily mobilized and redistributed into voids than organic nitrogen enriched in the heavy isotope.

M. A. Ivanova, C. A. Lorenz, M. Humayun, K. Richter, C. M. Corrigan, I. A. Franchi, A. B. Verchovsky, E. V. Korochantseva, V. V. Kozlov, S. N. Teplyakova, Kononkova N. N., and A. V. Korochantsev, Vernadsky Institute of Geochemistry and Analytical Chemistry, Moscow 119991, Russia; meteorite2000@mail.ru, National Museum of Natural History, Smithsonian Institution, USA; National High Magnetic Field Laboratory and Department of Earth, Florida State University, USA; Planetary and Space Sciences Research Institute, Open University, UK, Mailcode XI2, NASA JSC, USA Oxford Instruments OM & Gatan Inc., Moscow, Russia .

METHODS IN THE LUNAR DHOFAR 1436 METEORITE. E.V. Korochantseva 1,2 , A.I. Buikin 1 , J. Hopp 2 , A.B. Verchovsky 3 , A.V. Korochantsev 1 , M. Anand 3 , and M. Trieloff 2 , 1 Vernadsky Institute of Geochemistry, Kosygin St. 19, 119991 Moscow, Russia, 2 Institut für Geowissenschaften, Klaus-Tschira-Labor für Kosmochemie, Universität Heidelberg, Im Neuenheimer Feld 234-236, 69120 Heidelberg, Germany, 3 School of Physical Sciences, The Open University, Milton Keynes, MK7 6AA, UK(e-mail: Mario.Trieloff@geow.uni-heidelberg.de).

We present results of petrographic, mineralogical, and chemical investigations of three Chelyabinsk meteorite fragments. Three distinct lithologies were identified: light S3LL5, dark S4-S5LL5 material, and opaque fine-grained former impact melt. Olivine-spinel thermometry revealed an equilibration temperature of 703 +/- 23 degrees C for the light lithology. All plagioclase seems to be secondary, showing neither shock-induced fractures nor sulfide-metal veinlets. Feldspathic glass can be observed showing features of extensive melting and, in the dark lithology, as maskelynite, lacking melt features and retaining grain boundaries of former plagioclase. Olivine of the dark lithology shows planar deformation features. Impact melt is dominated by Mg-rich olivine and resembles whole-rock melt. Melt veins (<2mm) are connected to narrower veinlets. Melt vein textures are similar to pegmatite textures showing chilled margins, a zone of inward-grown elongated crystals and central vugs, suggesting crystallization from supercooled melt. Sulfide-metal droplets indicate liquid immiscibility of both silicate and sulfide as well as sulfide and metal melts. Impact melting may have been an important factor for differentiation of primitive planetary bodies. Graphite associated with micrometer-sized melt inclusions in primary olivine was detected by Raman mapping. Carbon isotopic studies of graphite could be applied to test a possible presolar origin.

The comment by Andronicos et al. (2017) on our paper entitled "Composition and origin of holotype Al-Cu-Zn minerals in relation to quasicrystals in the Khatyrka meteorite" by Ivanova et al. (2017) is essentially a review of the previous studies published by a group of investigators who have studied the Khatyrka sample found in 2011 (henceforth, the Khatyrka 2011 team), intended to refute our suggestion of a possible industrial origin of Cu,Al-bearing alloys. The comment largely focuses on the description of sample recovery and superiority of the Khatyrka 2011 field team over our team, which has little relevance to the main point of our paper which addresses the origin of Cu,Al-bearing alloys based on their chemical composition. The comment also discusses textural relationships among silicates and Cu,Al-bearing alloys, including quasicrystals, in the Khatyrka samples, but, as in their previous publications, avoids direct discussion of the alloy origin. Because arguments of both teams are described well enough to draw independent conclusions by an educated reader, we see no need to reply to every critical point raised in the comment and our response focuses on the main issue responding only to the comments which distort our observations or conclusions. While the comment emphasizes our failure to recover Khatyrka meteorite fragments, it does acknowledge the most important result of our fieldwork—the discovery of widespread previous human activity in the Listvenitovy Stream valley and its contamination by industrial materials. According to a member of the first gold-prospecting team, their work in the Listvenitovy Stream valley began in 1975, ~4 years before the recovery of the first Al,Cu-rich alloys on the site in 1979. The Khatyrka 2011 team has not reported on such contamination before, so previous readers, including us, were given the impression that the Khatyrka samples were collected in a pristine stream valley. In fact, it is our failure to recover Khatyrka meteorite samples or Al,Cu-rich alloys that led us to re-examination of the holotype sample that, by the Mining Museum (St. Petersburg, Russia) regulations, can be done only in Russia. Our petrographic and EPMA study of the chemical composition of the holotype sample along with the assessment of its thermal history and formation redox conditions led us to the conclusion that the observed combination is highly unlikely for a natural environment. Therefore, an industrial origin of the holotype sample was suggested based on the widespread evidence of contamination of the site by Al-based alloys. Because natural Al-rich alloys invariably contain Si and may contain other elements (Fe, Mg, Mn, Cu, Zn, etc.) depending on the type of rock they reside in, the lack of Si in the holotype sample and the Khatyrka meteorite alloys is consistent with a nonnatural origin of these alloys. Further support for this idea comes from the recent experiments on shock formation of khatyrkite (Hamman et al. 2016) and quasicrystals (Asimow et al. 2016). The khatyrkite grains crystallized from a melt generated by a high-velocity impact of Cu-bearing aluminum projectiles into quartz sand targets contain more than 1 wt% Si, consistent with the presence of Si in natural Al-rich alloys. The icosahedral phase formed in a shock recovery experiment on a layered target (olivine, Al-Cu alloys, Canyon Diablo meteorite) embedded into a stainless steel container contains 1.48–5.22 wt% Cr and 1.85–2.55 wt% Ni in addition to Al, Fe, and Cu, confirming that all these elements easily alloy together even on the short time scale of a shock experiment. Furthermore, we recently found that Devarda's alloy (wt%: 49–51 Cu, 44–46 Al, 4–6 Zn), compositionally nearly identical to the holotype sample (wt%: 47.4 Cu, 46.7 Al, 5.9 Zn), is a common reagent used in chemical testing for the nitrate ion since the beginning of the 20th century. It is still commercially produced. The comment by Andronicos et al. concludes that our idea on the anthropogenic origin of the Cu,Al-rich alloys is highly speculative. We agree, as we clearly stated in our paper. Moreover, we suggested how this idea can be tested. The origin of Cu,Al-rich alloys can be tested directly by trace element analysis. We could not carry out such an analysis due to the "nondestructive study" conditions imposed by the Museum. However, we believe it would be very reasonable for the Khatyrka 2011 team, which includes highly experienced geo- and cosmochemists and petrologists, to conduct such a test, and present the results in a publication. Yet, nothing has been reported so far. Instead, the Khatyrka 2011 team continues to rely on circumstantial evidence for an ad hoc extraterrestrial origin of the alloys that now requires (Lin et al. 2017) a multistage history of processes which are neither known nor expected to occur naturally. Therefore, we insist that until a suite of trace element data on Cu,Al-rich alloys becomes available, the idea of an industrial origin of aluminides and in situ mixing of them with silicates remains valid and preferable to an ad hoc extraterrestrial origin. We thank Dr. Michael Schreiber, two anonymous reviewers, and Associate Editor Prof. Christian Koeberl for fruitful comments and suggestions which significantly improved our reply. Dr. Christian Koeberl