CERES IN THE STAGNANT-LID REGIME: GEOPHYSICAL EVOLUTION OF THE CRUST

Ceres is the largest body of main belt [1], considered the link between the icy satellites of the outer solar system and the rocky asteroid of the inner region. By studying it, we can deduce crucial information about the formation and evolution of the bodies of our solar system. Ceres is thought to be differentiated [2,3]: a rocky core (probably with metals), an icy mantle (partially liquid?) and a crust, on which exposed ice is very difficult to find [4].In this work we study the geophysical and thermal evolution of Ceres, target of NASA Dawn mission, with a particular interest on the crust [5]. By assuming that a stagnant-lid regime is valid, we test different geophysical structures in order to study both temperature and thermal flux emitted by the surface and the thermal evolution of the crust and, eventually, its fracturing (with consequently exposition of buried materials). We assume that post-differentiation Ceres is stratified in three main layer (core, mantle and crust) characterized by different thermal and compositional features. The presence of long-lived radionuclides is considered as heat-source, while a fixed a temperature on surface is set. Several heat flux scaling laws are considered: isoviscous, variable viscosity Newtonian stagnant-lid, a non-Newtonian silicate like rheology with a stress dependence [6]. Our results could offer a theoretical support to the Ceres' data analysis, in particular on surface composition.

[1] Russell C. T., Raymond C. A., 2011, Space Sci. Rev., 163, 3

[2] Castillo-Rogez J. C., McCord T. B., 2010, Icarus, 205, 443

[3] McCord T. B., Sotin C., 2005, Journal of Geophysical Research (Planets), 110, 5009

[4] Formisano M., et al. MNRAS, submitted (2015).

[5] Formisano M., et al., in preparation (2015).

[6] Freeman J., 2005, Plan. and Space Science., 54, 2-14