Geochronology and palaeoclimatic context of submerged siliciclastic beachrock formation in the western Mediterranean Sea

This article describes the geomorphological and petrological characteristics of 19 submerged beachrocks located on the north Catalan coast (western Mediterranean Sea). Their length ranges between 8 and 1039 m, their width between 1.5 and 86.5 m and their thickness between 0.4 and 3.25 m. They are siliciclastic beachrocks consisting of well-rounded gravels with a very coarse sand matrix, and they have a low proportion of bioclasts (<1%). Cementation occurred in the swash zone and adjacent foreshore due to the precipitation of high magnesium calcite. From absolute dates (14C and optically stimulated luminescence) and anthropic artifacts, three phases of formation attributable to the Late Holocene were identified. Phase I corresponds to the warm and humid Roman Period and was recorded at a level below -3.75 m mean sea level (MSL). Phase II corresponds to the warm and arid Medieval Climate Anomaly and was recorded at +0.25 m to -2.5 m MSL. Phase III corresponds to the Little Ice Age and Industrial Period and was recorded at levels ranging from +0.5 m to -3.0 m MSL. Good temporal correspondence between the chronology of the cementation phases and warm and/or dry palaeoclimatic conditions can be established.