^1,2,3T. Salge,³H. Stosnach,⁴G. Rosatelli,^2,5L. Hecht,^2,6W. U. Reimold
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13283]
¹Natural History Museum, Imaging and Analysis Centre, Cromwell Road, SW7 5BD London, UK
²Museum für Naturkunde, Leibniz‐Institut für Evolutions‐ und Biodiversitätsforschung, Invalidenstrasse 43, 10115 Berlin, Germany
³Bruker Nano GmbH, Am Studio, 12489 Berlin, Germany
⁴Dipertimento Disputer, Università G. d’Annunzio, 66100 Chieti, Italy
⁵Institut für Geologische Wissenschaften, Freie Universität Berlin, Malteserstraße 74‐100, 12249 Berlin, Germany
⁶ Laboratory of Geochronology, Instituto de Geociências, Universidade de Brasília, 70910 900 Brasília, DF, Brazil
Published by arrangement with John Wiley & Sons

Drill core UNAM‐7, obtained 126 km from the center of the Chicxulub impact structure, outside the crater rim, contains a sequence of 126.2 m suevitic, silicate melt‐rich breccia on top of a silicate melt‐poor breccia with anhydrite megablocks. Total reflection X‐ray fluorescence analysis of altered silicate melt particles of the suevitic breccia shows high concentrations of Br, Sr, Cl, and Cu, which may indicate hydrothermal reaction with sea water. Scanning electron microscopy and energy‐dispersive spectrometry reveal recrystallization of silicate components during annealing by superheated impact melt. At anhydrite clasts, recrystallization is represented by a sequence of comparatively large columnar, euhedral to subhedral anhydrite grains and smaller, polygonal to interlobate grains that progressively annealed deformation features. The presence of voids in anhydrite grains indicates SO_x gas release during anhydrite decomposition. The silicate melt‐poor breccia contains carbonate and sulfate particles cemented in a microcrystalline matrix. The matrix is dominated by anhydrite, dolomite, and calcite, with minor celestine and feldspars. Calcite‐dominated inclusions in silicate melt with flow textures between recrystallized anhydrite and silicate melt suggest a former liquid state of these components. Vesicular and spherulitic calcite particles may indicate quenching of carbonate melts in the atmosphere at high cooling rates, and partial decomposition during decompression at postshock conditions. Dolomite particles with a recrystallization sequence of interlobate, polygonal, subhedral to euhedral microstructures may have been formed at a low cooling rate. We conclude that UNAM‐7 provides evidence for solid‐state recrystallization or melting and dissociation of sulfates during the Chicxulub impact event. The lack of anhydrite in the K‐Pg ejecta deposits and rare presence of anhydrite in crater suevites may indicate that sulfates were completely dissociated at high temperature (T > 1465 °C)—whereas ejecta deposited near the outer crater rim experienced postshock conditions that were less effective at dissociation.

^1,3Gyollai, I.,¹Kereszturi, Á.,²Chatzitheodoridis, E.
Central European Geology 62, 56-82 Link to Article [DOI: 10.1556/24.61.2018.12]
¹Konkoly Thege Miklós Astronomical Institute, HAS Research Centre for Astronomy and Earth Sciences, Budapest, Hungary
²Department of Geological Sciences, School of Mining and Metallurgical Engineering, National Technical University of Athens, Athens, Greece
³Geobiomineralization, Astrobiology Research Group, HAS Research Centre for Astronomy and Earth Sciences, Institute for Geological and Geochemical Research, Budaörsi út 45., Budapest, H-1112, Hungary

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

Klaus M. Pontoppidan¹, Colette Salyk², Andrea Banzatti³, Geoffrey A. Blake⁴, Catherine Walsh⁵, John H. Lacy⁶, and Matthew J. Richter⁷
Astrophysical Journal 874, 92 Link to Article [DOI: 10.3847/1538-4357/ab05d8 ]
¹Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
²Vassar College Physics and Astronomy Department, 124 Raymond Avenue, Poughkeepsie, NY 12604, USA
³Lunar and Planetary Laboratory, The University of Arizona, Tucson, AZ 85721, USA
⁴Division of Geological and Planetary Sciences, California Institute of Technology, MC 150-21, 1200 E California Boulevard, Pasadena, CA 91125, USA
⁵School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
⁶Department of Astronomy, The University of Texas at Austin, 2515 Speedway, Stop C1400, Austin, TX 78712, USA
⁷Department of Physics, University of California Davis, 1 Shields Avenue, Davis, CA 95616, USA

The dominant reservoirs of elemental nitrogen in protoplanetary disks have not yet been observationally identified. Likely candidates are HCN, NH₃, and N₂. The relative abundances of these carriers determine the composition of planetesimals as a function of disk radius due to strong differences in their volatility. A significant sequestration of nitrogen in carriers less volatile than N₂ is likely required to deliver even small amounts of nitrogen to the Earth and potentially habitable exoplanets. While HCN has been detected in small amounts in inner disks (<10 au), so far only relatively insensitive upper limits on inner disk NH₃ have been obtained. We present new Gemini-TEXES high-resolution spectroscopy of the 10.75 μm band of warm NH₃, and use two-dimensional radiative transfer modeling to improve previous upper limits by an order of magnitude to at 1 au. These NH₃ abundances are significantly lower than those typical for ices in circumstellar envelopes (). We also consistently retrieve the inner disk HCN gas abundances using archival Spitzer spectra, and derive upper limits on the HCN ice abundance in protostellar envelopes using archival ground-based 4.7 μm spectroscopy ([HCN_ice]/[H₂O_ice] < 1.5%–9%). We identify the NH₃/HCN ratio as an indicator of chemical evolution in the disk, and we use this ratio to suggest that inner disk nitrogen is efficiently converted from NH₃ to N₂, significantly increasing the volatility of nitrogen in planet-forming regions.

¹Y.Kebukawa et al. (>10)
Scientific Reports 9, 3169 Link to Article [DOI: 10.1038/s41598-019-39357-1]
¹Faculty of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

¹M.A.Fitzgerald,²K.B.Knight,²J.E.Matzel,¹K.R.Czerwinski
Chemical Geology 507,96-119 Link to Article [https://doi.org/10.1016/j.chemgeo.2018.12.018]
¹University of Nevada Las Vegas, 4505 S. Maryland Pkwy, Las Vegas, NV 89154, USA
²Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

¹Trey A.Lobpries,¹Thomas J.Lapen
Journal of African Earth Sciences 150,673-684 Link to Article [https://doi.org/10.1016/j.jafrearsci.2018.09.020]
¹Department of Earth and Atmospheric Sciences, University of Houston, 312 Science and Research 1, 3507 Cullen Blvd, Rm. 312, Houston, TX, 77204, USA

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

¹Abhishek K.Rai,^1,2Jayanta K.Pati,³Rohit Kumar
Optics&Laser Technology 114, 146-157 Link to Article [https://doi.org/10.1016/j.optlastec.2019.01.028]
¹Department of Earth and Planetary Sciences, Nehru Science Centre, University of Allahabad, Allahabad 211 002, India
²National Center of Experimental Mineralogy and Petrology, 14, Chatham Lines, University of Allahabad, Allahabad 211 002, India
³Department of Physics, C.M.P. Degree College, University of Allahabad, Allahabad 211 002, India

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

^1,2Sergey N. Britvin,³Vladimir V. Shilovskikh,⁴Renato Pagano,³Natalia S. Vlasenko,⁵Anatoly N. Zaitsev,⁵Maria G. Krzhizhanovskaya,³Maksim S. Lozhkin,⁵Andrey A. Zolotarev,⁵Vladislav V. Gurzhiy
Scientific Reports 9, 1047 Link to Article [https://doi.org/10.1038/s41598-018-37795-x]
¹Institute of Earth Sciences, Saint-Petersburg State University, Universitetskaya Nab. 7/9, 199034, St. Petersburg, Russia
²Kola Science Center of Russian Academy of Sciences, Fersman Str. 14, 184209, Apatity, Murmansk Region, Russia
³Centre for Geo-Environmental Research and Modelling, Saint-Petersburg State University, Ulyanovskaya ul. 1, 198504, St. Petersburg, Russia
⁴Casella Postale 37, Cinisello, Milano, Italy
⁵Institute of Earth Sciences, Saint-Petersburg State University, Universitetskaya Nab. 7/9, 199034, St. Petersburg, Russia

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

Tobias Steinpilz, Jens Teiser, and Gerhard Wurm
Astrophysical Journal 874, 60 Link to Article [DOI: 10.3847/1538-4357/ab07bb ]
University of Duisburg-Essen, Faculty of Physics, Lotharstr. 1-21D, Duisburg 47057, Germany

In the past, laboratory experiments and theoretical calculations showed a mismatch in the derived sticking properties of silicates in the context of planetesimal formation. It has been proposed by Kimura et al. that this mismatch is due to the value of the surface energy assumed, supposedly correlated to the presence or lack of water layers of different thickness on a grain’s surface. We present tensile strength measurements of dust aggregates with different water content here. The results are in support of the suggestion by Kimura et al. Dry samples show increased strengths by a factor of up to 10 over wet samples. A high value of γ = 0.2 J m⁻² likely applies to the dry low pressure conditions of protoplanetary disks and should be used in the future.

B. Zhao (赵斌)¹ and S. Q. Zhang (张双全)²
Astrophysical Journal 874, 5 Link to Article [DOI: 10.3847/1538-4357/ab0702 ]
¹School of Physics and Nuclear Energy Engineering, Beihang University Beijing 100191, People’s Republic of China
²School of Physics, Peking University, Beijing 100871, People’s Republic of China

The influence of the new mass model Weizsäcker–Skyrme 4 (WS4) on the r-process abundance distribution is investigated using the site-independent classical r-process and the site-dependent dynamical r-process models. The dynamical r-process calculations are performed under the neutrino-driven wind scenario. In comparison with the finite-range droplet model (FRDM) often used in r-process calculations, better agreement between the calculated abundance and the observed solar r-process abundance is found in both the classical and dynamical calculations by using the mass model WS4. The abundance underestimations at the A ~ 115, 140, and 200 mass regions encountered with the calculations using the FRDM is overcome to a large extent by using WS4.