Figure 3: Diagrammatic, interpretive cross-sections through the Thaumasian region, showing its hypothetical topographic evolution through time. The interpretation suggested here is the occurrence of differential vertical displacements in time and space of fractured crust, which may reflect compensation at depth by horizontal movement of subcrustal magmatic fluid. Note the reversal of the direction of vertical movements during the “topographic wave” outward migration, and the cracks on the crest of the doming.
Labelled features are: PC = Basement nappes of the Palaeo-chain; NC = Sedimentary nappes of the Neo-chain, included thick gypsum mega- breccias on the top (not indicated here, but for the description of such resedimented clastic evaporites); TB = Trap basalts; e₁, e₂ = erosional surfaces; ad = axial dykes; ft = frontal thrusts.