Neutron Capture Isotopes in the Martian Regolith and Implications for Martian Atmospheric Noble Gases

Rao, M. N.; Bogard, D. D.; Nyquist, L. E.; McKay, D. S.; Masarik, J.

doi:10.1006/icar.2001.6809

Cited by 29 publications

(49 citation statements)

References 69 publications

(129 reference statements)

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“…In a recent study Rao et al (2002) calculated the production of 8oKr from neutron capture of 79Br in the martian regolith. Impact-produced glasses in some martian meteorites have trapped significant amounts of the recent martian atmosphere.…”

Section: Neutron-produced Noble Gasesmentioning

confidence: 99%

Ejection ages from krypton‐81‐krypton‐83 dating and pre‐atmospheric sizes of martian meteorites

Eugster

Busemann

Lorenzetti

et al. 2002

Meteorit & Planetary Scien

107

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Abstract-Cosmic-ray exposure (CRE) ages and Mars ejection times were calculated from the radionuclide 81% with previously obtained CRE ages from the stable noble gas nuclei 3He, 21Ne, and 38Ar shows excellent agreement. This indicates that the method for the production rate calculation for the stable nuclei is reliable. In all martian meteorites we observe effects induced by secondary cosmic-ray produced epithennal neutrons. Epithermal neutron fluxes, @, (30-300 eV), are calculated based on the reaction 79Br(n, yp)gOKr. We show that the neutron capture effects were induced in free space during Mars-Earth transfer of the meteoroids and that they are not due to a pre-exposure on Mars before ejection of the meteoritic material. Neutron fluxes and slowing down densities experienced by the meteoroids are calculated and pre-atmospheric sizes are estimated. We obtain minimum radii in the range of 22-25 cm and minimum masses of 150-220 kg. These results are in good agreement with the mean sizes reported for model calculations using current semiempirical data.-

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Section: Neutron-produced Noble Gasesmentioning

confidence: 99%

Ejection ages from krypton‐81‐krypton‐83 dating and pre‐atmospheric sizes of martian meteorites

Eugster

Busemann

Lorenzetti

et al. 2002

Meteorit & Planetary Scien

107

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“…These authors attributed these excesses to neutron capture and spallation reactions in the Martian regolith. Produced isotopes would have been subsequently degassed into the Martian atmosphere (Rao, 2002). However, Conrad et al (2016) noted that krypton and xenon trapped in Martian meteorites do not present such excesses.…”

Section: Introductionmentioning

confidence: 99%

Noble gases and nitrogen in Tissint reveal the composition of the Mars atmosphere

Avice¹,

Bekaert²,

Aoudjehane³

et al. 2018

Geochem. Persp. Let.

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Comparative planetology is crucial to unravel the origin and evolution of volatile elements on terrestrial planets. We report precise measurements of the elemental and isotopic composition of nitrogen and noble gases in the Martian meteorite Tissint. Ar-N 2 correlations confirm discrepancies between results from Viking and Martian meteorites and those from the Mars Science Laboratory (MSL) mission. The Martian atmospheric 40 Ar/ 36 Ar ratio is estimated to be 1714 ± 170 (1σ), lower than the value determined by Viking but in agreement with, and with higher precision than, data from MSL. We confirm a solar wind-like origin for Martian Kr and Xe. Excesses on light Kr isotopes are lower than those measured by MSL. Cosmogenic excesses in the Xe isotopic spectrum could have been produced in space during exposure of the Tissint parent body to cosmic rays.

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“…Measurements from the Mars Odyssey gamma-ray spectrometer (GRS) revealed a global chlorine content of 0.49 wt% for the Mars surface (Keller et al, 2006), consistent with MER lander measurements of ß0.3 wt% (Rao et al, 2002). Since these values are considerably higher than the chlorine abundance of the & Ellis (1983), Heald et al (1987) and Arnórsson et al (2007).…”

Section: Chlorine and Bromine Abundancesmentioning

confidence: 66%

“…Martian mantle and crust (0.015-0.039 wt%) (Lodders & Fegley, 1997;Rao et al, 2002;Taylor et al, 2010) and SNC meteorites (0.0014-0.11 wt%) (Dreibus & Wänke, 1987;Banin et al, 1992), secondary processes are likely to be responsible for this enrichment (Keller et al, 2006). The NWA 6234 shergottite has a bulk Cl content of 59 ppm and a Br/Cl molar ratio of 0.0040 (Burguess et al, 2013), comparable to the molar Br/Cl ratios of 0.0025 for Mars' bulk composition (Taylor et al, 2010).…”

Section: Chlorine and Bromine Abundancesmentioning

confidence: 99%

Volcanic hydrothermal systems as potential analogues of Martian sulphate-rich terrains

Aguilar

Bergen

2015

Netherlands Journal of Geosciences

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Remote sensing observations and rover missions have documented the presence of sulphate-rich mineral associations on Mars. Many of these minerals are paleo-indicators of hydrous, acidic and oxidising environments that must have prevailed in Mars´distant past, contrary to the present conditions. Furthermore, occurrences of silica together with high Cl and Br concentrations in Martian soils and rocks represent fingerprints of chemically atypical fluids involved in processes operating on the surface or at shallow depth. From field observations at representative active volcanoes in subduction settings, supported by geochemical modelling, we demonstrate that volcanic hydrothermal systems are capable of producing Mars-like secondary mineral assemblages near lakes, springs and fumaroles through the action of acidic fluids. Water-gas-rock interactions, together with localised flow paths of water and fumarolic gas emitted from associated subaerial vents, lead to deposition of a range of sulphates, including gypsum, jarosite, alunite, epsomite and silica. Evaporation, vapour separation and fluid mixing in (near-) surface environments with strong gradients in temperature and fluid chemistry further promote the diversity of secondary minerals. The mineralogical and chemical marks are highly variable in space and time, being subject to fluctuations in ambient conditions as well as to changes in the status of volcanic-hydrothermal activity. It is concluded that active processes in modern volcanic-geothermal systems may be akin to those that created several of the sulphate-rich terrains in the early history of Mars.

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Neutron Capture Isotopes in the Martian Regolith and Implications for Martian Atmospheric Noble Gases

Cited by 29 publications

References 69 publications

Ejection ages from krypton‐81‐krypton‐83 dating and pre‐atmospheric sizes of martian meteorites

Ejection ages from krypton‐81‐krypton‐83 dating and pre‐atmospheric sizes of martian meteorites

Noble gases and nitrogen in Tissint reveal the composition of the Mars atmosphere

Volcanic hydrothermal systems as potential analogues of Martian sulphate-rich terrains

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