Paleoenvironment and taphonomy of lower Miocene bivalve and macroid assemblages: the Lagos Biocalcarenite (Lagos-Portimão Formation, southern Portugal)

Geological-Geomorphological and Paleontological Heritage in the Algarve (Portugal) Applied to Geotourism and Geoeducation

“…The site displays an architecture (stacking and morphology of the strata) with three types of sequences of eustatic origin, Orbital origin (Milankovitch cycles) and caused by storms. Sedimentary structures also suggest superficial currents from the Mediterranean to the Atlantic (inverse to the present one) [36,37].…”

Storm-Related Rhodolith Deposits from the Upper Pleistocene and Recycled Coastal Holocene on Sal Island (Cabo Verde Archipelago)

“…Based on the nucleation pattern of the Malbusca rhodoliths with few basalt cores, they are likely to have dwelled a bit father offshore than the São Nicolau rhodoliths but still in relatively shallow water. Small rhodoliths with a diameter between 4 and 5 cm are also reported in accumulations as much as a half-meter in thickness from the Lower Miocene of the Lagos-Portimão Formation in southern Portugal [16]. The exposed contact at Lagos between Miocene and Cretaceous strata is a paraconformity between limestone units.…”

“…Geosciences 2020, 10, x FOR PEER REVIEW 3 of 18 highlight patterns of long-term atmospheric circulation and storm dynamics in the region through Neogene time. To this end, Sal Island Pleistocene and Holocene rhodoliths are compared with older Pliocene and Miocene rhodoliths farther afield in the Cabo Verde Archipelago and neighboring islands in the northeast Atlantic Ocean [12][13][14][15] as well as mainland Portugal [16] in order to underscore features that are peculiar to Sal Island.…”

“…Analysis of Ocean-Drilling-Program (ODP) Site 659 located east of Sal Island [34], indicates a higher level of terrigenous influx off the Cabo Verde plateau between 6.2 and 4.9 million years ago than typical today. The inference is that elevated levels of storminess led to enhanced rainfall over the islands on the plateau and this factor may account for the occurrence of the extensive Miocene rhodolith deposits on São Nicolau Island [12], as well as other places like Madeira [13] and southern Portugal [16]. Such differences in the organization of the ITCZ in a more northerly position are marshalled to account for changes registered as far north as Malta in the Mediterranean Sea following the Messinian Salinity Crisis [34,35].…”

“…Hence, the coastal areas of these islands offer a dynamic laboratory for study of beaches, supratidal berms, and sand dunes directly related to the onshore mobilization and post-mortem disintegration of substantial rhodolith deposits. Studies based on Miocene to Pliocene deposits that demonstrate offshore to onshore transport of rhodoliths include those from São Nicolau in the Cabo Verde Islands [12], Ilhéu de Cima off Porto Santo in Madeira [13,14], and Santa Maria Island in the Azores [15], as well as mainland Portugal [16]. Individual rhodolith fossils from deposits in these places vary in diameter between one or two centimeters to a maximum of 20 cm as recorded on Ilhéu de Cima [13].…”