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Mars' atmospheric 40Ar: A tracer for past crustal erosion

Leblanc, F. and Chassefiere, E. and Gillmann, C. and Breuer, D. (2012) Mars' atmospheric 40Ar: A tracer for past crustal erosion. Icarus: International Journal of Solar System Studies, 218 (1), pp. 561-570. Elsevier. doi: 10.1016/j.icarus.2012.01.006.

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Official URL: http://www.sciencedirect.com/science/article/pii/S0019103512000218


Noble gas 40Ar may be used as a tracer of the past evolution of volatiles in Mars’ crust, mantle and atmosphere. 40Ar is formed by the radioactive decay of 40K in the mantle and in the crust and is released from the mantle to the atmosphere due to volcanism and from the crust by erosion such as eolian and hydrothermal erosion. Furthermore, 40Ar can escape from the atmosphere into space via atmospheric escape mechanisms. The evolution of the atmospheric abundance of 40Ar thus depends on these three processes whose efficiencies vary with time. In the present study we reconsider atmospheric escape mechanism efficiencies and describe various possible scenarios of the evolution of 40Ar with a model describing the three main reservoirs of 40Ar, the mantle, crust and atmosphere. First, we show that atmospheric escape, which is stronger in the early evolution, does not significantly influence the present abundance of the atmospheric40Ar. In the early evolution the atmospheric concentration of 40Ar is very low as the outgassing of 40Ar from the mantle occurs relatively late in the martian evolution. Thus, the atmospheric40Ar concentration is essentially a tracer of Mars’ outgassing history and not of the escape processes. Second, using the results of the most recent published crustal formation models, the calculated present 40Ar atmospheric abundance is smaller than its observed value. This discrepancy may be explained by a significant 40Ar supply from the crust by erosion (16–30% of the 40Ar content of the upper first 10 km of crust). The knowledge of the fraction of crustal 40Ar outgassed to the atmosphere is an important constraint for any future global modelling of past Mars' hydrothermal activity aiming at better characterizing the role of subsurface aqueous alteration processes in Mars climate evolution. One of the main sources of the uncertainty of these results is the present uncertainty in the measured atmospheric40Ar value (+/-20%). More precise measurements of 40Ar and 36Ar in the martian atmosphere are therefore required to better constrain the model. ----- Highlights: 1) We model Mars40Ar atmosphere, mantle and crust. 2) Present atmosphere content cannot be reproduced with Mars' formation model. 3) This suggests a significant crust past erosion.

Item URL in elib:https://elib.dlr.de/75863/
Document Type:Article
Title:Mars' atmospheric 40Ar: A tracer for past crustal erosion
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Leblanc, F.LATMOS/IPSL, CNRS, Université Pierre et Marie CurieUNSPECIFIEDUNSPECIFIED
Gillmann, C.Institut für Geophysik, Department of Earth Sciences, ZürichUNSPECIFIEDUNSPECIFIED
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
Page Range:pp. 561-570
Keywords:Atmospheres, Composition; Mars, Atmosphere; Atmospheres, Evolution
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Space (old)
HGF - Program Themes:W EW - Erforschung des Weltraums
DLR - Research area:Space
DLR - Program:W EW - Erforschung des Weltraums
DLR - Research theme (Project):W - Vorhaben Exploration des Sonnensystems (old)
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Planetary Research > Planetary Physics
Institute of Planetary Research
Deposited By: Noack, Lena
Deposited On:27 Jun 2012 14:44
Last Modified:10 Jan 2019 15:47

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