¹Travis J. Tenner,¹Daisuke Nakashima,¹Takayuki Ushikubo,¹Noriko T. Kita,^2,3Michael K. Weisberg
¹WiscSIMS, Department of Geoscience, University of Wisconsin-Madison, Madison, WI 53706, USA
²Kingsborough Community College and Graduate Center, The City University of New York, 2001 Oriental Boulevard, Brooklyn, NY 11235-2398, USA
³American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024-5192, USA

We present detailed electron microprobe analyses and oxygen three-isotope measurements by high precision secondary ion mass spectrometry on 45 type I (FeO-poor) chondrules/fragments and 3 type II (FeO-rich) chondrule fragments from Meteorite Hills 00426 and Queen Alexandra Range 99177, two of the most primitive CR3 chondrites. Type I chondrules/fragments have Mg#’s (defined as the Mg# of constituent olivine and/or low-Ca pyroxene) ranging from 94.2 to 99.2; type II chondrule fragments have Mg#’s of 53–63. Oxygen three-isotope measurements plot on the slope ∼1 primitive chondrule mineral (PCM) line. Within chondrules, Δ17O (=δ17O–0.52 × δ18O) values of coexisting olivine, pyroxene, and plagioclase are homogeneous, with propagated uncertainties of 0.3‰. This indicates each phase crystallized from the final chondrule melt, and that efficient oxygen isotope exchange occurred between ambient gas and chondrule melt. Among type I chondrules there is a well-defined increase in Δ17O, from –5.9‰ to ∼−1‰, as Mg#’s decrease from 99.2 to ∼96; type II chondrule fragments are comparatively 16O-poor (Δ17O: ∼0.2–0.6‰). The relationship between Mg# and Δ17O among type I chondrules confirms that addition of a 16O-poor oxidizing agent to the highest Mg# chondrule precursors resulted in forming lower Mg# CR chondrules. Using aspects of existing equilibrium condensation models and a mass balance we estimate that type I CR chondrules formed at dust enrichments of 100–200×, from dusts with 0–0.8 times the atomic abundance of ice, relative to CI dust. The type II chondrule fragments are predicted to have formed at CI dust enrichments near 2500×.

Reference
Tenner TJ, Nakashima D, Ushikubo T, Kita NT, Weisberg MK (2014) Oxygen isotope ratios of FeO-poor chondrules in CR3 chondrites: Influence of dust enrichment and H2O during chondrule Formation. Geochimica et Cosmochimica Acta (in Press)
Link to Article [DOI: 10.1016/j.gca.2014.09.025]

Copyright Elsevier

¹M. Nagasawa, ²K. K. Tanaka, ²H. Tanaka, ³T. Nakamoto, ⁴H. Miura, ⁵T. Yamamoto
¹Interactive Research Center of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan
²Institute of Low Temperature Science, Hokkaido University, Kita-19, Nishi-8, Kita-ku, Sapporo 060-0819, Japan
³Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan
⁴Graduate School of Natural Sciences, Nagoya City University, 1 Yamanohata, Mizuho-cho, Mizuho-ku, Nagoya 467-8501, Japan
⁵Center for Planetary Science, Kobe University, 7-1-48 Minamimachi, Minatojima, Chuo-ku, Kobe 650-0047, Japan

It is proposed that planetesimals perturbed by Jovian mean-motion resonances are the source of shock waves that form chondrules. It is considered that this shock-induced chondrule formation requires the velocity of the planetesimal relative to the gas disk to be on the order of gsim 7 km s–1 at 1 AU. In previous studies on planetesimal excitation, the effects of Jovian mean-motion resonance together with the gas drag were investigated, but the velocities obtained were at most 8 km s–1 in the asteroid belt, which is insufficient to account for the ubiquitous existence of chondrules. In this paper, we reexamine the effect of Jovian resonances and take into account the secular resonance in the asteroid belt caused by the gravity of the gas disk. We find that the velocities relative to the gas disk of planetesimals a few hundred kilometers in size exceed 12 km s–1, and that this is achieved around the 3:1 mean-motion resonance. The heating region is restricted to a relatively narrowband between 1.5 AU and 3.5 AU. Our results suggest that chondrules were produced effectively in the asteroid region after Jovian formation. We also find that many planetesimals are scattered far beyond Neptune. Our findings can explain the presence of crystalline silicate in comets if the scattered planetesimals include silicate dust processed by shock heating.

Reference
Nagasawa M, Tanaka KK, Tanaka H, Nakamoto T, Miura H, Yamamoto T (2014) Revisiting Jovian-resonance Induced Chondrule Formation. The Astrophysical Journal Letters 794, 1, L7
Link to Article [doi:10.1088/2041-8205/794/1/L7]

^1,2José M. Madiedo et al. (>10 Authors)*
¹Departamento de Física Atómica, Molecular y Nuclear, Facultad de Física, Universidad de Sevilla, 41012 Sevilla, Spain
²Facultad de Ciencias Experimentales, Universidad de Huelva, 21071 Huelva, Spain
*Find the extensive, full author and affiliation list on the publishers website

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Reference
José M. Madiedo et al. (2014) Trajectory, orbit, and spectroscopic analysis of a bright fireball observed over Spain on April 13, 2013. Astronomy&Astrophysics 569 (in Press)
Link to Article [http://www.aanda.org/articles/aa/abs/2014/09/aa22120-13/aa22120-13.html]

^1,2Yoko Kebukawa,³Michael E. Zolensky,⁴A. L. David Kilcoyne,⁵Zia Rahman,^6,7Peter Jenniskens,¹George D. Cody
¹Geophysical Laboratory, Carnegie Institution of Washington, Washington, District of Columbia, USA
²Department of Natural History Sciences, Hokkaido University, Sapporo, Japan
³NASA Johnson Space Center, Houston, Texas, USA
⁴Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California, USA
⁵Jacobs-Sverdrup, Houston, Texas, USA
⁶SETI Institute, Mountain View, California, USA
⁷NASA Ames Research Center, Moffett Field, California, USA

The Sutter’s Mill (SM) meteorite fell in El Dorado County, California, on April 22, 2012. This meteorite is a regolith breccia composed of CM chondrite material and at least one xenolithic phase: oldhamite. The meteorite studied here, SM2 (subsample 5), was one of three meteorites collected before it rained extensively on the debris site, thus preserving the original asteroid regolith mineralogy. Two relatively large (10 μm sized) possible diamond grains were observed in SM2-5 surrounded by fine-grained matrix. In the present work, we analyzed a focused ion beam (FIB) milled thin section that transected a region containing these two potential diamond grains as well as the surrounding fine-grained matrix employing carbon and nitrogen X-ray absorption near-edge structure (C-XANES and N-XANES) spectroscopy using a scanning transmission X-ray microscope (STXM) (Beamline 5.3.2 at the Advanced Light Source, Lawrence Berkeley National Laboratory). The STXM analysis revealed that the matrix of SM2-5 contains C-rich grains, possibly organic nanoglobules. A single carbonate grain was also detected. The C-XANES spectrum of the matrix is similar to that of insoluble organic matter (IOM) found in other CM chondrites. However, no significant nitrogen-bearing functional groups were observed with N-XANES. One of the possible diamond grains contains a Ca-bearing inclusion that is not carbonate. C-XANES features of the diamond-edges suggest that the diamond might have formed by the CVD process, or in a high-temperature and -pressure environment in the interior of a much larger parent body.

Reference
Kebukawa Y, Zolensky ME, Kilcoyne ALD, Rahman Z, Jenniskens P, Cody GD (2014) Diamond xenolith and matrix organic matter in the Sutter’s Mill meteorite measured by C-XANES. Meteoritics&Planetary Science (in Press)
Linke to Article [DOI: 10.1111/maps.12312]

Published in agreement with John Wiley&Sons

¹Yamakawa, A. ¹Yin, Q.-Z.
¹Department of Earth and Planetary Sciences, University of California at Davis, Davis, California, USA

Recent studies have shown that major meteorite groups possess their own characteristic 54Cr values, demonstrating the utility of Cr isotopes for identifying genetic relationships between the planetary materials in conjunction with other classical tools, such as oxygen isotopes. In this study, we performed Cr isotope analyses for whole rocks and chemically separated phases of the new CM2 chondrite, Sutter’s Mill (SM 43 and 51). The two whole rocks of Sutter’s Mill show essentially identical ε54Cr excesses (SM 43 = +0.95 ± 0.09ε, SM 51 = +0.88 ± 0.07ε), relative to the Earth. These values are the same within error with that of the CM2-type Murchison (+0.89 ± 0.08ε), suggesting that parent bodies of Sutter’s Mill and Murchison were formed from the same precursor materials in the solar nebula. Large ε54Cr excess of up to 29.40ε is observed in the silicate phase of Sutter’s Mill, while that of Murchison shows 15.74ε. Importantly, the leachate fractions of both Sutter’s Mill and Murchison form a steep linear anticorrelation between ε54Cr and ε53Cr, cross-cutting the positive correlation previously observed in carbonaceous chondrites. The fact that L4 acid leachate fraction contains higher 54Cr excesses than that of L5 step designed to dissolve refractory minerals suggests that spinel is not a major 54Cr carrier. We also note that L5 contains 53Cr anomalies lower than the solar initial value, suggesting it carries a component of nucleosynthetic anomaly unrelated to the 53Mn decay. We have identified five endmember components of nucleosynthetic origin among the early solar system materials.

Reference
Yamakawa A, Yin Q-Z (2014) Chromium isotopic systematics of the Sutter’s Mill carbonaceous chondrite: Implications for isotopic heterogeneities of the early solar system. Meteoritics & Planetary Science (in Press)
Link to Article [doi: 10.1111/maps.12346]

Published by arrangement with John Wiley&Sons

¹Yesiltas, M., ²Kebukawa, Y., ¹Peale, R. E., ³Mattson, E., ³Hirschmugl, C. J., ^4,5Jenniskens, P.
¹Department of Physics, University of Central Florida, Orlando, Florida, USA
²Faculty of Engineering, Yokohama National University, Hodogaya-ku, Yokohama, Japan
³Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, USA
⁴SETI Institute, Mountain View, California, USA
⁵NASA Ames Research Center, Moffett Field, California, USA

Synchrotron-based Fourier transform infrared spectroscopy and Raman spectroscopy are applied with submicrometer spatial resolution to multiple grains of Sutter’s Mill meteorite, a regolith breccia with CM1 and CM2 lithologies. The Raman and infrared active functional groups reveal the nature and distribution of organic and mineral components and confirm that SM12 reached higher metamorphism temperatures than SM2. The spatial distributions of carbonates and organic matter are negatively correlated. The spatial distributions of aliphatic organic matter and OH relative to the distributions of silicates in SM2 differ from those in SM12, supporting a hypothesis that the parent body of Sutter’s Mill is a combination of multiple bodies with different origins. The high aliphatic CH2/CH3 ratios determined from band intensities for SM2 and SM12 grains are similar to those of IDPs and less altered carbonaceous chondrites, and they are significantly higher than those in other CM chondrites and diffuse ISM objects.

Reference
Yesiltas M, Kebukawa Y, Peale RE, Mattson E, Hirschmugl CJ, Jenniskens P (2014) Infrared imaging spectroscopy with micron resolution of Sutter’s Mill meteorite grains. Meteoritics & Planetary Science (in Press)
Link to Article [doi: 10.1111/maps.12321]

Published by arangement with John Wiley&Sons

¹Takaaki Noguchi et al. (>10 Autors)*
¹Faculty of Arts and Science, Kyushu University, 744 Motooka, Nishi-ku,
Fukuoka 819-0395, Japan
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Reference
Noguchi T et al. (2014) Mineralogy of four Itokawa particles collected from the first touchdown site.
Earth, Planets and Space 66:124
Link to Article [doi:10.1186/1880-5981-66-124]

¹Alicia Noel,¹Janice L. Bishop,^2,3Muna Al-Samir,²Christoph Gross,
⁵Jessica Flahaut,^2,4Patrick C. McGuire,⁶Catherine M. Weitz,⁴Frank Seelos,⁴Scott Murchie

¹Carl Sagan Center, The SETI Institute, Mountain View, CA 94043, USA
²Planetary Science and Remote Sensing Group, Institute of Geosciences, Freie Universität Berlin, 12249 Berlin, Germany
³DLR, Institute of Planetary Research, Berlin, Germany
⁴Applied Physics Laboratory, Laurel, MD 20723, USA
⁵Earth and Life Sciences, Vrije Universiteit (VU) Amsterdam, Amsterdam, Netherlands
⁶Planetary Sciences Institute, Tucson, AZ 85721, USA

Juventae Chasma is a deep depression located north of Valles Marineris on Mars, with four bright mounds or light-toned interior layered deposits (ILDs) extending upwards from the Canyon floor. We present here the results of long-term imaging of Juventae Chasma including mounds A, B, C, and D using multiple datasets. Monohydrated sulfates (MHS) were deposited first on the canyon floor, followed by polyhydrated sulfates (PHS). The upper PHS-dominated units are largely eroded away at Juventae Chasma, but this material is still present in significant abundance at mound B. PHS are observed mixed with MHS in some areas of mounds A and C. Terraces are observed at the upper elevations of mound B that contain PHS at the steeper slopes and appear to be covered with dust on the horizontal surfaces. Current analyses of the MHS-rich unit indicate that kieserite (MgSO4⋅H2O) is the primary sulfate component, rather than szomolnokite (FeSO4⋅H2O) as previously thought. Formation of kieserite at Juventae Chasma likely required temperatures in the 150–200 °C range. Geochemical modeling is most consistent with dissolution of mafic materials followed by precipitation of kieserite from solution. The dust exhibits ferric signatures and the sand is largely mafic material. Outcrops of olivine- and pyroxene-bearing rocks are best observed along the base of mound C and in the chaotic terrain surrounding mound D. This study summarizes the current understanding of Juventae Chasma and its ILDs using HRSC, HiRISE and CTX data, an expanded laboratory spectral library, and the latest calibrations available for CRISM.

Reference
Noel A, Bishop JL, Al-Samir M, Gross C, Flahaut J, McGuire PC, Weitz CM, Seelos F, Murchie S (2014) Mineralogy, morphology and stratigraphy of the light-toned interior layered deposits at Juventae Chasma. Icarus (in Press)
Link to Article [DOI: 10.1016/j.icarus.2014.09.033]

Copyright Elsevier

¹V. S. Antipin, ¹M. I. Kuz’min, ²D. M. Pecherskii, ³V. A. Tsel’movich, ⁴. A. Yazev
¹Vinogradov Institute of Geochemistry, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia
²Schmidt Joint Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, Russia
³Borok Geophysical Observatory, Schmidt Joint Institute of Physics of the Earth, Russian Academy of Sciences, Borok, Yaroslavl’ oblast, Russia
⁴Irkutsk State University, Irkutsk, Russia

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Reference
Antipin VS, Kuz’min MI, Pecherskii DM, Tsel’movich VA, Yazev SA (2014) The substance of the Chelyabinsk meteorite: Results of geochemical and thermomagnetic studies. Doklady Akademii Nauk 458, 57–60.
Link to Article [10.1134/S1028334X14090013]

¹Min Tang,^1,2Anouk Ehreiser,¹Yi-Liang Li
¹Department of Earth Sciences, The University of Hong Kong, Pokfulam, Hong Kong
²Department of Physics and Astronomy, Heidelberg University, Postfach 10 57 60, 69047 Heidelberg, Germany

Gypsum is a mineral that commonly precipitates in hydrothermal environments. This study reports the electron microscopic analyses of gypsum morphologies and crystal sizes found in hot springs on the Kamchatka Peninsula, Russia, and compares these analyses with gypsum morphologies of hydrothermal genesis found in Lower Cambrian black shale. In sediments of the Kamchatka hot springs, we observed prismatic, prismatic pseudo-hexagonal, fibrous, tubular, lenticular and twinned gypsum crystals, with crystal sizes ranging from 200 μm. The coexistence of diverse crystal habits of gypsum implies a constant interaction between hot spring geochemistry and the metabolisms of the microbial community. The crystallization of Ca- and Ba-sulfates in the black shale of the Lower Cambrian, which shows similar but less varied morphology, was influenced by post-depositional hydrothermal fluids. The partial replacement of pyrite by sulfates in a situation coexisting with rich biomass deposits and animal fossils indicates limited modification of the sedimentary records by biological materials. If the gypsum precipitated on Mars underwent similar interactions between microbial communities and their geochemical environments, the resulting crystal habits could be preserved even better than those on Earth due to the weak geodynamics prevailing on Mars throughout its evolutionary history.

Reference
Tang M, Ehreiser A, Li, Y-L (2014) Gypsum in modern Kamchatka volcanic hot springs and the Lower Cambrian black shale: Applied to the microbial-mediated precipitation of sulfates on Mars. American Mineralogist 99, 2126-2137,
Link to Article: [doi:10.2138/am-2014-4754]

Copyright: The Mineralogical Society of America