(a) Detailed photograph of a brecciated carbonate lens at the base of the sub-site R (see Fig. 5 for location). (b) The thin-section natural illumination displays veins and clasts forming a jigsaw-like structure. (c) The thin-section polarized illumination shows mineralizations in veins and conduits. Four different calcites have been identified: C1, in red, is an iron-rich micro-sparitic calcite generally found in shell fragments or thin veins; C2, in blue, is a brown drusy calcite that is in contact with the micritic matrix and is usually coating clasts; C3, in green, and C4, in purple, are equant or blocky calcite filling all remaining space. Isotopic analyzes (C, O and Sr) were conducted on four samples (see text for details).