ALBERT

Description: Lago Argentino hosts various calving glaciers, among them the famous Perito Moreno. Whereas the onland late Pleistocene–Holocene glacial history is rather well constrained, the submerged glacier-related features were until now undisclosed. Here we present a series of high-resolution seismic profiles revealing moraine bodies associated with the late-glacial glacier dynamics and the first bathymetric map of the Brazo Rico and Brazo Sur, the two southern arms of Lago Argentino. At the eastern termination of Brazo Rico, we identified at the lake floor the submerged expression of the Puerto Bandera 3 moraine mapped onshore, which represents the oldest event (12,660 ± 70 cal yr BP oldest minimum age) recognized in this lake arm, and seven other younger events expressed by a series of terminal and recessional moraines. Along the Brazo Sur, few moraine bodies have been imaged by seismic data. Here, the youngest temporal constraint comes from the Frías moraine (ca. 6000 cal yr BP), which closes off the southern end of the Brazo Sur. At the confluence of the two arms, the Perito Moreno and the former Frías glacier merged and flowed toward east during their late-glacial maximum advance (i.e., Puerto Bandera 1 moraine). The subaqueous evidence of moraine bodies testifies to the occurrence of previously undocumented pulses of the Perito Moreno and former Frías glaciers within the general phase of late Pleistocene–Holocene regression.

Description: A 25 m-thick outcrop section exposed at Torre Mucchia, on the sea-cliff north of Ortona, eastern central Italy, comprises a rare Middle Pleistocene succession of shallow-water and paralic sediments along the western Adriatic Sea. An integrated study of the section, including facies and microfacies analyses, and characterization of paleobiological associations (mollusks, fishes, ostracods, foraminifers and pollen), enable a detailed reconstruction of the paleoenvironmental and paleoclimatic conditions during deposition. The shallow-water deposits include a transgressive, deepening- and fining-upward shoreface to offshore-transition facies succession overlain by a regressive shoreface-foreshore sandstone body with an erosive base and a rooted and pedogenically altered horizon at the top that imply deposition during sea-level fall. This forced regressive unit is overlain by paralic strata forming a transgressive succession comprising palustrine carbonates and back-barrier lagoonal mudstones. The palustrine carbonates exhibit some of the typical features encountered in palustrine limestones deposited within seasonal freshwater wetlands (marl prairies). Following the sea-level rising trend, the freshwater marshes were abruptly replaced by a barrier-lagoon system that allowed deposition of the overlying mud-rich unit. Within these deposits, the faunal assemblages are consistent with a low-energy brackish environment characterized by a relatively high degree of confinement. The pollen record documents the development of open forest vegetation dominated by Pinus and accompanied by a number of mesophilous and thermophilous tree taxa, whose composition supports a tentative correlation with Marine Oxygen Isotope Stage 17. The new pollen record from Torre Mucchia improves our understanding of the vegetation development in the Italian Peninsula during the Middle Pleistocene and sheds new light on the role played by the most marked glacial periods in determining the history of tree taxa.

Description: The Sicilian Channel is a broad and shallow shelf which is geologically part of the African Plate. Its NW sector (the Adventure Plateau), where water depths rarely exceed 100 m, is punctuated by several kilometre-sized morphological highs. These elevations, formed by both sedimentary and volcanic rocks, emerged around middle Holocene time or earlier when they constituted a large archipelago. High-resolution single-channel and multichannel seismic reflection profiles, along with stratigraphic and lithological information derived from exploration wells and rock samplings, are analysed to derive the shallow and deep structural setting of these banks and identify their geological nature. The sedimentary banks (Talbot, Ante-Talbot, Panope, Nereo and Pantelleria Vecchia), presently located at water depths 8–40 m, are composed of Miocene rocks severely deformed by a late Miocene compressional phase which produced the external sector of the Sicilian–Maghrebian thrust belt. Tortonian-aged rock samples from the Pantelleria Vecchia Bank represent patch reefs that have mostly formed on structural highs. Sedimentary analogies suggest that other sedimentary banks of the Adventure Plateau may have the same origin. Galatea, Anfitrite and Tetide represent submarine volcanic edifices emplaced on major extensional faults formed during early Pliocene – Quaternary continental rifting of the Sicilian Channel. The present-day morphology of the banks is the result of repeated phases of subaerial exposure and drowning, especially since the Last Glacial Maximum.