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

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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.