I just read an interesting article on "Episodic outgassing as the origin of atmospheric methane on Titan" (Tobie et al., 2006. Nature, Vol. 440, No. 4497, 61-64). It describes the evolution of Titan's interior and the resulting release of methane (3 episodes). The second episode of outgassing is supposed to have taken place 2-2.5 Gyr ago due to core convection. Prior to that Titan's core heated up due to diffusive heating which finally led to a thinning of the outer methane clathrate layer and subsequent release of methane.
Is the diffusive heating a differentiation processes within the core? What is it exactly?
It would be great if someone could help me understand it.
Michael