Harry Y. McSween Jr.¹, Theodore C. Labotka¹ and Christina E. Viviano-Beck²

¹Department of Earth and Planetary Sciences and Planetary Geoscience Institute, University of Tennessee, Knoxville, Tennessee, USA
²The Johns Hopkins Applied Physics Laboratory, Laurel, Maryland, USA

Compositions of basaltic and ultramafic rocks analyzed by Mars rovers and occurring as Martian meteorites allow predictions of metamorphic mineral assemblages that would form under various thermophysical conditions. Key minerals identified by remote sensing roughly constrain temperatures and pressures in the Martian crust. We use a traditional metamorphic approach (phase diagrams) to assess low-grade/hydrothermal equilibrium assemblages. Basaltic rocks should produce chlorite + actinolite + albite + silica, accompanied by laumontite, pumpellyite, prehnite, or serpentine/talc. Only prehnite-bearing assemblages have been spectrally identified on Mars, although laumontite and pumpellyite have spectra similar to other uncharacterized zeolites and phyllosilicates. Ultramafic rocks are predicted to produce serpentine, talc, and magnesite, all of which have been detected spectrally on Mars. Mineral assemblages in both basaltic and ultramafic rocks constrain fluid compositions to be H₂O-rich and CO₂-poor. We confirm the hypothesis that low-grade/hydrothermal metamorphism affected the Noachian crust on Mars, which has been excavated in large craters. We estimate the geothermal gradient (>20 °C km⁻¹) required to produce the observed assemblages. This gradient is higher than that estimated from radiogenic heat-producing elements in the crust, suggesting extra heating by regional hydrothermal activity.

Reference
McSween HY, Labotka TC and Viviano-Beck CE (in press) Metamorphism in the Martian crust. Meteoritics & Planetary Science
[doi:10.1111/maps.12330]
Published by arrangement with John Wiley & Sons

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A. Sezer¹ and F. Gök²

¹TÜBİTAK Space Technologies Research Institute, ODTU Campus, Ankara, 06531, Turkey
²Akdeniz University, Faculty of Education, Department of Secondary Science and Mathematics Education, Antalya, 07058, Turkey

In this work, we present results from a ~201.6 ks observation of G352.7–0.1 using the X-ray Imaging Spectrometer on board SuzakuX-ray Observatory. The X-ray emission from the remnant is well described by two-temperature thermal models of non-equilibrium ionization with variable abundances with a column density of N_H ~ 3.3 × 10²² cm^-2. The soft component is characterized by an electron temperature of kT_e ~ 0.6 keV, an ionization timescale of τ ~ 3.4 × 10¹¹ cm^-3 s, and enhanced Si, S, Ar, and Ca abundances. The hard component has kT_e ~ 4.3 keV, τ ~ 8.8 × 10⁹ cm^-3 s, and enhanced Fe abundance. The elemental abundances of Si, S, Ar, Ca, and Fe are found to be significantly higher than the solar values that confirm the presence of ejecta. We detected strong Fe K-shell emission and determined its origin to be the ejecta for the first time. The detection of Fe ejecta with a lower ionization timescale favors a Type Ia origin for this remnant.

Reference
Sezer A and Gök F (2014) Fe-rich Ejecta in the Supernova Remnant G352.7–0.1 with Suzaku. The Astrophysical Journal 790:81.
[doi:10.1088/0004-637X/790/1/81]

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