Evolution of the neutron density (lower panel, in logarithm) and of the abundances of selected heavy element species (upper panel, in logarithm) as a function of time during the main phase of the neutron superburst (t = 0 corresponds to the same time as in Figs. 1 and 2 and to the onset of the neutron flux). Abundances are sampled at 0.29 M_⊙, the location of the maximum neutron density. All abundances, except those of protons and neutrons, are homogeneous within the HeCZ, and therefore their values in the plot are representative of the abundances in the whole region.