¹Earl O’Bannon III, ¹Quentin Williams
Physics and Chemistry of Minerals 43, 181–208   Link to Article [doi:10.1007/s00269-015-0786-1]
¹Department of Earth and Planetary Sciences University of California Santa Cruz USA

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

^1,2Youmo Zhou,¹Tetsuo Irifune,¹Hiroaki Ohfuji,¹Toru Shinmei,^1,2Wei Du
Physics and Chemistry of Minerals (in Press) Link to Article [DOI: 10.1007/s00269-016-0834-5]
¹Geodynamics Research Center Ehime University Matsuyama Japan
²Earth-Life Science Institute Tokyo Institute of Technology Tokyo Japan

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

¹A. Rodríguez, ¹M.J. van Bergen
Netherlands Journal of Geosciences 95, 153-169 Link to Article [DOI: http://dx.doi.org/10.1017/njg.2015.12]
¹Department of Earth Sciences, Utrecht University, Budapestlaan 4, 3508 TA, Utrecht, the Netherlands

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

¹Shuai Li, ¹Ralph E. Milliken
Journal of Geophysical Research Planets (in Press) Link to Article [DOI: 10.1002/2016JE005035]
¹Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, RI, USA
Published by arrangement with John Wiley & Sons

Radiance measured by the Moon Mineralogy Mapper (M3) at wavelengths beyond ~2 µm commonly includes both solar reflected and thermally emitted contributions from the lunar surface. Insufficient correction (removal) of the thermal contribution can modify and even mask absorptions at these wavelengths in derived surface reflectance spectra, an effect that precludes accurate identification and analysis of OH and/or H2O absorptions. This study characterized thermal effects in M3 data by evaluating surface temperatures measured independently by the Lunar Reconnaissance Orbiter Diviner radiometer, and results confirm that M3 data (Level 2) currently available in the Planetary Data System (PDS) often contain significant thermal contributions. It is impractical to use independent Diviner measurements to correct all M3 images for the Moon because not every M3 pixel has a corresponding Diviner measurement acquired at the same local time of lunar day. Therefore, a new empirical model, constrained by Diviner data, has been developed based on the correlation of reflectance at 1.55 µm and at 2.54 µm observed in laboratory reflectance spectra of Apollo and Luna soil and glass-rich samples. Reflectance values at these wavelengths follow a clear power law, inline image, for a wide range of lunar sample compositions and maturity. A nearly identical power law is observed in M3 reflectance data that have been independently corrected using Diviner-based temperatures, confirming this is a general reflectance property of materials that typify the lunar surface. These results demonstrate that reflectance at a thermally-affected wavelength (2.54 µm) can be predicted within 2% (absolute) based on reflectance values at shorter wavelengths where thermal contributions are negligible and reflectance is dominant. Radiance at 2.54 µm that is in excess of the expected amount is assumed to be due to thermal emission and is removed during conversion of at-sensor radiance to reflectance or I/F. Removal of this thermal contribution using this empirically-based model provides a more accurate view of surface reflectance properties at wavelengths >2 µm, with the benefit that it does not require independent measurements or modeling of surface temperatures at the same local time as M3 data were acquired. It is demonstrated that this model is appropriate for common lunar surface compositions (e.g., mare and highlands soils, pyroclastic deposits), but surface compositions with reflectance properties that deviate strongly from these cases (e.g., pyroxene-, olivine-, or spinel-rich locations with minimal space weathering) may require the use of more sophisticated thermal correction models or overlapping Diviner temperature estimates.

¹Kyoungwon Min, ¹Annette Farah, ²Seung Ryeol Lee, ³Jong Ik Lee
Geochimica et Cosmochimica Acta (in Press) Link to Article [http://dx.doi.org/10.1016/j.gca.2016.09.009]
¹Department of Geological Sciences, University of Florida, Gainesville, FL 32611, USA
²Korea Institute of Geosciences and Mineral Resources, Daejeon, Korea
³Korea Polar Research Institute, Incheon, Korea
Copyright Elsevier

Shock conditions of martian meteorites provide crucial information about ejection dynamics and original features of the martian rocks. To better constrain equilibrium shock temperatures (Tequi-shock) of martian meteorites, we investigated (U-Th)/He systematics of moderately-shocked (Zagami) and intensively shocked (ALHA77005) martian meteorites. Multiple phosphate aggregates from Zagami and ALHA77005 yielded overall (U-Th)/He ages 92.2 ± 4.4 Ma (2σ) and 8.4 ± 1.2 Ma, respectively. These ages correspond to fractional losses of 0.49 ± 0.03 (Zagami) and 0.97 ± 0.01 (ALHA77005), assuming that the ejection-related shock event at ∼3 Ma is solely responsible for diffusive helium loss since crystallization. For He diffusion modeling, the diffusion domain radius is estimated based on detailed examination of fracture patterns in phosphates using a scanning electron microscope. For Zagami, the diffusion domain radius is estimated to be ∼2-9 μm, which is generally consistent with calculations from isothermal heating experiments (1-4 μm). For ALHA77005, the diffusion domain radius of ∼4-20 μm is estimated.

Using the newly constrained (U-Th)/He data, diffusion domain radii, and other previously estimated parameters, the conductive cooling models yield Tequi-shock estimates of 360-410 °C and 460-560 °C for Zagami and ALHA77005, respectively. According to the sensitivity test, the estimated Tequi-shock values are relatively robust to input parameters. The Tequi-shock estimates for Zagami are more robust than those for ALHA77005, primarily because Zagami yielded intermediate fHe value (0.49) compared to ALHA77005 (0.97). For less intensively shocked Zagami, the He diffusion-based Tequi-shock estimates (this study) are significantly higher than expected from previously reported Tpost-shock values. For intensively shocked ALHA77005, the two independent approaches yielded generally consistent results. Using two other examples of previously studied martian meteorites (ALHA84001 and Los Angeles), we compared Tequi-shock and Tpost-shock estimates. For intensively shocked meteorites (ALHA77005, Los Angeles), the He diffusion-based approach yield slightly higher or consistent Tequi-shock with estimations from Tpost-shock, and the discrepancy between the two methods increases as the intensity of shock increases. The reason for the discrepancy between the two methods, particularly for less-intensively shocked meteorites (Zagami, ALHA84001), remains to be resolved, but we prefer the He diffusion-based approach because its Tequi-shock estimates are relatively robust to input parameters.

¹Petr Vítek, ²Carmen Ascaso, ³Octavio Artieda, ²Jacek Wierzchos
Analytical and Bioanalytical Chemistry 408, 4083 Link to Article [doi:10.1007/s00216-016-9497-9]
¹Global Change Research Institute, v.v.i.The Czech Academy of Sciences Brno Czech Republic
²Museo Nacional de Ciencias Naturales, CSIC Madrid Spain
³Departamento Biología Vegetal, Ecología y Ciencias de la Tierra Universidad de Extremadura Plasencia Spain

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

¹Xunyu Zhang,^1,2Yunzhao Wu,³Ziyuan Ouyang,¹Roberto Bugiolacchi,²Yuan Chen,^2,4Xiaomeng Zhang,¹²Wei Cai,¹Aoao Xu,¹Zesheng Tang
Journal of Geophysical Research Planets (in Press) Link to Article [DOI: 10.1002/2016JE005051]
¹Space Science Institute, Macau University of Science and Technology, Macau, China
²School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing, China
³National Astronomical Observatories, Chinese Academy of Sciences, Beijing, China
⁴Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, China
Published by arrangement with John Wiley & Sons

The last major phases of lunar volcanism occurred mainly in Oceanus Procellarum and Mare Imbrium, and produced spectrally unique medium-high titanium basalts. The composition and distribution of these basalts provide a record of the late stage thermal evolution of the Moon. To study the spectral and mineralogical variations of the late stage mare basalts, 31 distinct units were mapped employing a range of remote sensing data. Their inferred mineralogical characteristics were studied by analyzing the spectral features of small, fresh craters derived from the Moon Mineralogy Mapper (M3) data. The strongest olivine spectral signatures were found around Lichtenberg crater, while the units with the lowest olivine/pyroxene ratio occurred mainly in the southern Kepler crater and some local areas. In Oceanus Procellarum, the olivine/pyroxene ratio decreasesprogressively from the Lichtenberg crater to the southern units. The northern and southern units within Mare Imbrium have higher olivine/pyroxene ratios than the central ones. The inferred abundance of olivine appears to vary stratigraphically, with the younger flows being more olivine rich. However, the stratigraphically younger units around Euler crater in Mare Imbrium, which present as dark red hues in the Integrated Band Depth (IBD) image of M3, were found to have lower olivine/pyroxene ratios than the units around Lichtenberg crater (shown as light red hues) in Oceanus Procellarum. . It could be interpreted that the late stage mare basalts around Lichtenberg crater originated from a more olivine-rich source than those around Euler crater.

^1,2Yang Liu,¹Timothy D. Glotch,^1,3Noel A. Scudder,^1,4Meredith L. Kraner,¹Thomas Condus,⁵Raymond E. Arvidson,⁵Edward A. Guinness,⁶Michael J. Wolff,⁷Michael D. Smith
Journal of Geophysical Research Planets Link to Article [DOI: 10.1002/2016JE005028]
¹Department of Geosciences, Stony Brook University, Stony Brook, NY, USA
²Southwest Research Institute, San Antonio, TX, USA
³Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN, USA
⁴Nevada Geodetic Laboratory, University of Nevada Reno, Reno, NV, USA
⁵Department of Earth and Planetary Sciences, Washington University in St. Louis, St. Louis, Missouri, USA
⁶Space Science Institute, Boulder, CO, USA
⁷NASA Goddard Spaceflight Center, Greenbelt, MD, USA
Published by arrangement with John Wiley & Sons

We present spectral unmixing results over the southwest Melas Chasma region, where a variety of hydrated minerals were identified. We use the DISORT radiative transfer model to simultaneously model Mars atmospheric gases, aerosols, and surface scattering and retrieve the single scattering albedos (SSAs) modeled by the Hapke bidirectional scattering function from CRISM data. We employ a spectral unmixing algorithm to quantitatively analyze the mineral abundances by modeling the atmospherically corrected CRISM SSAs using a non-negative least squares (NNLS) linear deconvolution algorithm. To build the spectral library used for spectral unmixing, we use the factor analysis and target transformation (FATT) technique to recover spectral end-members within the CRISM scenes. We investigate several distinct geologic units, including an interbedded poly- and monohydrated sulfate unit (interbedded unit 1) and an interbedded phyllosilicate-sulfate unit (interbedded unit 2). Our spectral unmixing results indicate that, polyhydrated sulfates in the interbedded unit 1 have a much lower abundance (~10%) than that of the surrounding unit (~20%) and thus may have been partially dehydrated into kieserite to form the interbedded strata, supporting a two-staged precipitation-dehydration formation hypothesis. In the interbedded unit 2 phyllosilicates have an abundance of ~40% and are interbedded with ~20% sulfates. The results, in combination with thermodynamic calculations performed previously, suggest that the interbedded phyllosilicates and sulfates likely formed through coupled basalt weathering and evaporation. The methodology developed in this study provides a powerful tool to derive the mineral abundances, aiming to better constrain the formation processes of minerals and past aqueous environment on Mars.

¹Carle M. Pieters, ²Sarah K. Noble
Journal of Geophysical Research Planets (in Press) Link to Article [DOI: 10.1002/2016JE005128]
¹Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, RI
²Planetary Science Division, NASA Headquarters, Washington, DC
Published by arrangement with John Wiley & Sons

Space weathering refers to alteration that occurs in the space environment with time. Lunar samples, and to some extent meteorites, have provided a benchmark for understanding the processes and products of space weathering. Lunar soils are derived principally from local materials but have accumulated a range of optically active opaque particles (OAOpq) that include nanophase metallic iron on/in rims formed on individual grains (imparting a red slope to visible and near-infrared reflectance) and larger iron particles (which darken across all wavelengths) such as are often found within the interior of recycled grains. Space weathering of other anhydrous silicate bodies, such as Mercury and some asteroids, produce different forms and relative abundance of OAOpq particles depending on the particular environment. If the development of OAOpq particles is minimized (such as at Vesta), contamination by exogenic material and regolith mixing become the dominant space weathering processes. Volatile-rich bodies and those composed of abundant hydrous minerals (dwarf planet Ceres, many dark asteroids, outer solar system satellites) are affected by space weathering processes differently than the silicate bodies of the inner solar system. However, the space weathering products of these bodies are currently poorly understood and the physics and chemistry of space weathering processes in different environments are areas of active research.

¹L.M.Thompson et al. (>10)*
Journal of Geophysical Research Planets (in Press) Link to Article [DOI: 10.1002/2016JE005055]
¹Planetary and Space Science Centre, University of New Brunswick, Fredericton, NB, Canada
Published by arrangement with John Wiley & Sons
*Find the extensive, full author and affiliation list on the publishers website

The Alpha Particle X-ray spectrometer (APXS) onboard the Curiosity rover at the Kimberley location within Gale crater, Mars, analyzed basaltic sandstones that are characterized by potassium enrichments of two to eight times estimates for average martian crust. They are the most potassic rocks sampled on Mars to date. They exhibit elevated Fe, Mg, Mn and Zn, and depleted Na, Al and Si. These compositional characteristics are common to other potassic sedimentary rocks analyzed by APXS at Gale, but distinct from other landing sites and martian meteorites. CheMin and APXS analysis of a drilled sample indicate mineralogy dominated by sanidine, Ca-rich and Ca-poor clinopyroxene, magnetite, olivine and andesine. The anhydrous mineralogy of the Kimberley sample, and the normative mineralogy derived from APXS of other Bathurst class rocks, together indicate provenance from one or more potassium-rich magmatic or impact-generated source rocks on the rim of Gale crater or beyond. Elevated Zn, Ge and Cu suggest that a localized area of the source region(s) experienced hydrothermal alteration, which was subsequently eroded, dispersed and diluted throughout the unaltered sediment during transport and deposition. The identification of the basaltic, high potassium Bathurst class and other distinct rock compositional classes by the APXS, attests to the diverse chemistry of crustal rocks within and in the vicinity of Gale crater. We conclude that weathering, transport and diagenesis of the sediment did not occur in a warm and wet environment, but instead under relatively cold and wet conditions, perhaps more fitting with processes typical of glacial/periglacial environments.