Physics
Scientific paper
Dec 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011agufm.p33h..01s&link_type=abstract
American Geophysical Union, Fall Meeting 2011, abstract #P33H-01
Physics
[5480] Planetary Sciences: Solid Surface Planets / Volcanism, [6225] Planetary Sciences: Solar System Objects / Mars, [8147] Tectonophysics / Planetary Interiors, [8450] Volcanology / Planetary Volcanism
Scientific paper
We investigate the thermal evolution of Mars using a 1D parameterized mantle convection model in order to assess the effects of volcanic degassing on the mantle melting and crustal evolution of the planet. The volcanic activity on the surface of Mars is directly related to its thermal evolution through the melting process and we focus our study on the factors controlling this process. Our model incorporates the effects of variable water content both on the rheology and on the mantle solidus. Other investigators have previously studied the effects of water loss on martian thermal evolution, but those studies have always assumed a dry solidus and thus did not fully capture the feedbacks that are present in our new model. The core of the model is derived from the classical parameterization of the stagnant lid mantle convection. The rate of volatile degassing into the atmosphere by volcanic processes is scaled with the extent and concentration of the melt in the potential melt zone. The melt zone varies with the mantle temperature and with a water concentration dependent solidus. The growth of the crustal layer is calculated by integrating the melt flux and thus becomes dependent on the melting parameters. Along with the volatiles, the radioactive elements segregate into the crust as well. This has implication for the heat distribution in the system. The mantle viscosity is parameterized in terms of its temperature and volatile content and thus affects the thermal evolution by a complex set of feedback relationships. Preliminary results show how the melt zone evolution is controlled by the mantle temperature and by the bulk concentration of water in the mantle. The thermal evolution scenarios obtained using different parameterizations and composition assumptions are presented and tested against the information regarding both ancient and recent volcanism on the planet. An example of a successful simulation has an initial mantle water content of 600 ppm, a degassing efficiency of 0.03-0.05, and an initial mantle bulk temperature of 2000 K. This model is consistent with geochemical constraints on the current mantle water abundance and the extraction of incompatible elements from the mantle to the crust. It is consistent with geophysical constraints on the present-day mantle heat flux and can explain the observed cessation time of the magnetic dynamo using purely internal processes. The interior temperature remains high enough at present to permit a small amount of mantle plume volcanism, consistent with observations of the martian meteorites and of the impact cratering of young volcanos. Other elements whose abundances differ between Mars and Earth, like iron and sodium, also have significant roles in the control melting and viscosity. Ongoing modeling will assess the full range of allowed parameter values.
Kiefer Walter Scott
Sandu Constantin
No associations
LandOfFree
The Effects of Mantle Degassing on the Thermal and Magmatic Evolution of Mars does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Effects of Mantle Degassing on the Thermal and Magmatic Evolution of Mars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Effects of Mantle Degassing on the Thermal and Magmatic Evolution of Mars will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-871133