## 3 Geological Setting  
The Sardinia-Corsica block (Figure 4) is a continental microplate located in the western Mediterranean between the Ligurian-Provenal Basin and the Tyrrhenian Basin. Its present location is due to Cenozoic tectonic movements leading to its separation from the main European continent (southern France and the Iberian Peninsula) [43; 44; 45; 46; 47; 48; 49; 50]. Sardinia consists of a Variscan basement (intrusive and metamorphic rocks of variable degree, see small Sardinia sketch map in Figure 4, [51]) of Early Cambrian to Pennsylvania age partially covered by Late Palaeozoic to Pliocene-Quaternary sedimentary and volcanic rocks [52; 53; 54; 55; 56; 57; 58]. The widest and most continuous volcano-sedimentary covers crop out along the \"Sardinia Trough\", an Oligo-Miocene depression that crosses the island from north to south [52; 53; 54; 55], whose southern area was partially reactivated in the Pliocene-Quaternary forming the Campidano graben [56]. The Antas Temples is located in southwestern Sardinia (Iglesiente subregion) (Figure 4) that, from a geological point of view, pertains to the external zone of the Sardinian Variscan basement [59; 60] here characterized by the widespread occurrence of polydeformed, low to very low-grade metamorphic rocks belonging to a former sedimentary succession ranging in age from the Early Cambrian to the Late Ordovician (Figure 5). Different subdivisions of the Cambrian terms are proposed by authors [61; 62; 63]. Here we adopt the subdivision reported in the new 1: Iglesias Geological Sheet 555 by the Italian CARG project ([64], see legend of Figure 5). In the study area, the succession starts with the mainly terrigenous sediments of the Nebida Fm (Fm = Formation), made up of light grey metasiltstones (Matoppa Mb (Mb = Member)) at the bottom, and overlaid by rhythmic alternations of metasandstones, metasiltstones and metaclaystones with carbonate cement preserving algal mat laminae (Punta Manna Mb). The Gonnesa Fm (\"Gonnesa Group\" ([65], and references therein)) marks the change from a mainly siliciclastic to a clean carbonate sedimentation. The lower \"Laminated Metadolostone\" Mb consists of alternating, well stratified metadolostones and metalimestones hosting algal mats,olithic-oncolithic levels, thinly stratified carbonate muds and rare evaporites. The upper \"Ceroid Limestone\" Mb is made up by dark to light-grey, thickly stratified to massive metalimestones, locally affected by diagenetic dolomitization [66]. Eight kilometers eastward in the next Oridda area, a detailed sedimentological investigation of the carbonate Gonnesa Group was performed by Costamagna [67]: its sedimentological and paleogeographic results have been extended in the conclusions to the presently studied area. Figure 4: Geological sketch-map of the southwestern Sardinia coast with the location of the Antas Temple and other important archaeological sites from Punic and Roman times such as _Tharros_, _Forum Traini_, _Neapolis_ (with probable localization near to Antas site), _Sulki_, _Bitnia_, _Nora_, and ancient Punic-Roman quarries, such as _Is Aruttas_, _s’Enna ’e’s’Arca_, _Scivu_, _San Nicolao_, _Piscimi_, _Fradis Minoris_ and _Sa Perderedda_ (near to _Nora_ site). Geological base from RAS, 2010, modified [51]. Figure 5: Geological map of the area surrounding the Punic-Roman archaeological site of Antas (Fluminimaggiore, Sulcis, SW Sardinia). From RAS, 2010, modified [51]. The Campo Pisano Fm is mainly formed by grey to pinkish nodular metalimestones with an abundant fossiliferous content that dates the base of the formation at the middle Cambrian. Subordinate facies, consisting of massive metalimestones and metamarls, are also found. The Early Cambrian-Lower Ordovician succession ends with the \"Cabitza Schists\" Fm, consisting of a rhythmic alternating metacalaystones, metasilstones, and fine-grained metasandstones; the upper part of the formation has been assigned biostratigraphyically to the Early Ordovician.