Figure 4

SEM–EDS analyses on representative samples of Group 1, showing reacted dolostones and chert clasts displaying the development of M-S–H gels. Backscattered electrons (BSE) acquisitions. (a) WM_3, altered clasts of dolostone; (a1) EDS spectrum of the unreacted core of a dolostone clast; (a2) EDS spectrum of the Mg-depleted rim of the clasts, with local enrichment in M–(A)–S–H; (a3) EDS spectrum of the unreacted core of another dolostone clast; (a4) EDS spectrum of the Mg-depleted rim of the clasts, with local enrichment in M–(A)–S–H; (b) WM_3, altered clasts of chert; (c) magnification of the dashed area at fig. (b); (c1) EDS spectrum of a feebly altered core of a clast of chert; (c2) EDS spectrum of a reacted area of the clast, indicating a local development of M–(A)–S–H and a likely occurrence of C–S–H through reaction with the lime component; (d) PREF_12, lime matrix of the sample with a lime lump on the right; (e) magnification of the dashed area in fig. (d); (e1) EDS spectrum of an area of the binder matrix displaying M–S–H development; (e2) development of M–S–H within the micropores of a lime lump.