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Surface weathering on Venus: Constraints from kinetic, spectroscopic, and geochemical data

Dyar, M and Helbert, Jörn and Cooper, Reid F. and Sklute, Elizabeth C. and Maturilli, Alessandro and Müller, Nils and Kappel, David and Smrekar, Suzanne E. (2020) Surface weathering on Venus: Constraints from kinetic, spectroscopic, and geochemical data. Icarus: International Journal of Solar System Studies, p. 114139. Elsevier. doi: 10.1016/j.icarus.2020.114139. ISSN 0019-1035.

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Official URL: https://www.sciencedirect.com/science/article/abs/pii/S0019103520304802


On Venus, understanding of surface-atmosphere interactions resulting from chemical weathering is both critically important for constraining atmospheric chemistry and relative ages of surface features and multifaceted, requiring integration of diverse perspectives and disciplines of study. This paper evaluates the issue of surface alteration on Venus using multiple lines of evidence. Surface chemistry from Venera and Vega landers is inconsistent with significant breakdown from atmospheric interactions, with <2.0 wt% S or less observed. Consideration of kinetics and breakdown of basalt under Venus conditions indicates diffusion of Ca > Fe > Mg toward the oxidizing Venus atmosphere, favoring creation of anhydrite and carbonate-rich surfaces on basalts with minor addition of hematite. When related to Venus-analog experiments, the kinetic calculations suggest a maximum coating of ~30 μm over 500,000 years. These changes would result in a slight overall volume increase in the outermost surface materials, which in turn decreases surface rock FeO contents. Those variations can be detected from orbit because emissivity is correlated with total FeO, and the predicted magnitudes are consistent with Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) observations. Models of anhydrite and hematite coatings on basalt mixtures suggest that changes in emissivity (ε) spectra due to chemical weathering can result in ca. <0.08 shifts in total emissivity. Such gradations are small compared to the first-order effect of bulk composition on emissivity, which can cause up to ~0.80 emissivity shifts. For all these reasons, there is at present no evidence to suggest that impenetrable coatings of either hematite (ε = 0.8) or anhydrite (ε = 0.1) are present on Venus. Orbital measurements of surface emissivity on a global scale could therefore produce not only a map of rock type and surface composition based on transition metal contents (largely FeO) (Helbert et al., 2020) but also provide local scale assessments of fresh vs. mature lava flows on the surface.

Item URL in elib:https://elib.dlr.de/138725/
Document Type:Article
Additional Information:Bisher nur online erschienen.
Title:Surface weathering on Venus: Constraints from kinetic, spectroscopic, and geochemical data
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Dyar, MDept. of Astronomy, Mount Holyoke College, South Hadley, MA USAUNSPECIFIED
Helbert, JörnJoern.Helbert (at) dlr.dehttps://orcid.org/0000-0001-5346-9505
Cooper, Reid F.Dept. of Astronomy, Mount Holyoke College, South Hadley, MA USAUNSPECIFIED
Sklute, Elizabeth C.Dept. of Astronomy, Mount Holyoke College, South Hadley, MA USAUNSPECIFIED
Maturilli, AlessandroAlessandro.Maturilli (at) dlr.dehttps://orcid.org/0000-0003-4613-9799
Müller, NilsNils.Mueller (at) dlr.deUNSPECIFIED
Kappel, DavidDavid.Kappel (at) dlr.deUNSPECIFIED
Smrekar, Suzanne E.Jet Propulsion Laboratory, Mail Stop 183-501, 4800 Oak Grove Drive, Pasadena, CA 91109, USAUNSPECIFIED
Journal or Publication Title:Icarus: International Journal of Solar System Studies
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:Yes
DOI :10.1016/j.icarus.2020.114139
Page Range:p. 114139
Keywords:Venus, Spektroskopie, Weathering, VEM, Mineralogie
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Exploration
DLR - Research area:Raumfahrt
DLR - Program:R EW - Space Exploration
DLR - Research theme (Project):R - Venus Emissivity Mapper
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Planetary Research > Planetary Laboratories
Institute of Planetary Research > Planetary Physics
Deposited By: Helbert, Dr.rer.nat. Jörn
Deposited On:03 Dec 2020 15:14
Last Modified:20 Jun 2021 15:54

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