Fig. 10
From: Mars core structure—concise review and anticipated insights from InSight
Mars core structure when stratification and crystallization of an inner core occur simultaneously. Top panels show size of inner core (assumed Fe 3 S 2) and slight perturbation to density and P wave speed at the top of the outer core when stratification enriches sulfur in the core, lowering both density ρ and P wave speed in the outer core relative to unstratified state (red lines). The profiles of P, S and ρ in the inner core are labeled with (IC) for clarity; the unstratified P and ρ profiles (red) continue smoothly to Mars’ center. The inset (top right) of the boxed area near the CMB expands the density and P wavespeed profiles to emphasize their subtle structural changes. Bottom panels show ray paths and travel times for unstratified (left) and stratified (right) cases. The stratification itself is unobservable because P wavespeeds are already lower than S in the mantle, blocking minor-arc SKKS (Fig. 8, top). The only visible consequence of stratification is the presence of the inner core itself, indicated by the existence of PKiKP (and its extension to 180° as PKIKP)