Description: We present a geomorphological, stratigraphical and geochronological study reconstructing a suite of paleosurfaces in a 200 km-long coastal sector of the central Tyrrhenian Sea between Argentario and Circeo promontories. Identification of the near-shore deposits associated with these paleo-surfaces allow us to define corresponding marine terraces and paleo sea-levels. Ar-40/Ar-39 and ESR/U-Th geochronologic constraints on key deposits provide correlation with the terraces previously recognized in the coast of central Latium, refining their correlation with the Marine Isotopic Stages. Results of this study enable us to: Propose a re-assessment of the ages for the sea-level markers of MIS 5.5, 5.3, 5.1 in the central Tyrrhenian Sea; Suggest that a continuous tectonic uplift with an average rate of 0.224 mm/yr affects the Latium coast since 200 ka; Provide new evidence for a MIS 5.5 paleo-sea level marker occurring at -35 m a.s.l. on the coastal sector extending from Montalto di Castro to Latina, while it possibly drops down and connects to a paleo sea-level ranging 10 - 5 m between Monte Circeo and Gaeta, previously attributed to this interglacial; Discussing possible evidence of similar elevation of the sea level during MIS 5.5, 5.3 and 5.1 interglacials in the Tyrrhenian Sea; Compare this datum with those from the western Pacific and several coral reefs, where the differences with respect to tectonically stable regions were attributed either to tectonics or to the Glacial Isostatic Adjustment, showing that the presented record of sea-level markers may have a strong impact on modeling the post-glacial effects in the Mediterranean Sea and on the paleoclimatic and paleoceanographic studies in this region.

Description: Published

Description: 54-77

Description: 1A. Geomagnetismo e Paleomagnetismo

Description: 5A. Ricerche polari e paleoclima

Description: JCR Journal

Description: Subglacially precipitated carbonate crusts (SPCCs) formed on bedrock and till boulder surfaces adjacent to the Barnes Ice Cap (BIC), central Baffin Island, Arctic Canada, act as unique archives of Laurentide Ice Sheet basal conditions. Uranium-series dating of these features reveals that carbonate precipitation from subglacial meltwater occurred during the Last Glacial Maximum (LGM), requiring warm-based ice in the region at that time. However, the preservation of fragile SPCCs is unlikely beneath erosive warm-based ice, suggesting that the transition to subsequent cold-based conditions took place shortly after the LGM, and glacial erosion in the region occurred dominantly prior to the LGM. The oxygen isotopic composition of the meltwater from which the SPCCs precipitated is indistinguishable from that of the debris-rich BIC basal ice (d18O –24‰ referenced to Vienna standard mean ocean water), but distinct from that of the overlying white Pleistocene ice (d18O ~–35‰), demonstrating that SPCCs are reliable archives of the isotopic composition of only the basal ice of past ice sheets.

Description: The data sets include U-series and Neodymium isotope measurements in modern (n = 6) and fossil (n = 24) deep-coral (Desmophyllum dianthus) assemblages raised from the Orphan Knoll and Flemish cap area, southeastern Labrador Sea, during the CCGS Hudson-2010-029 cruise using the tethered Canadian ROPOS ROV, complemented with a single colony from a rock dredge recovery during the CSS Hudson 78-020 expedition. Fossil specimens age clusters are : the mid to late Holocene, the Bølling-Allerød (the single colony), MIS 5c, MIS 7a. Details about the U-series measurements can be found in Maccali et al. (2020). Nd-isotope measurements were reported during the 2015 Goldschmidt Conference by Ménabréaz et al. ( 2015). Low eNd-values point to intervals with a strong imprint of detrital particulate fluxes from the Greenland and Canadian Precambrian basements on the intermediate water mass of the Labrador Sea (~ 1600-2200 m). The more radiogenic end-member (eNd ~ -13.5) corresponds to the modern-like signature of the North-Atlantic Deep Sea Water.

Description: Core PS2757-6 was retrieved with a multicorer (MUC) on the Lomonosov Ridge next to the Russian continental shelf during the Polarstern expedition ARK-XI/1 in 1995. This expedition had the principal aim to study material fluxes and ecological connections between the Arctic Deep Basins and the adjacent Siberian shelf seas, the northern Laptev Sea and the northeastern Kara Sea. In 2018 and 2019, this core had samples analyzed by MC-ICPMS at the Geotop-UQAM laboratories for uranium-series isotopes with the aim to establish radiochronological age constraints for the coring location.

Description: Core PS2757-8 was taken with a Kastenlot corer (KAL) on the Lomonosov Ridge next to the Russian continental shelf during the Polarstern expedition ARK-XI/1 in 1995. This expedition had the principal aim to study material fluxes and ecological connections between the Arctic Deep Basins and the adjacent Siberian shelf seas, the northern Laptev Sea and the northeastern Kara Sea. In 2018 and 2019, the core had samples analyzed by MC-ICPMS at the Geotop-UQAM laboratories for uranium-series isotopes with the aim to establish radiochronological age constraints for the coring locations.

Description: We present a new mid-latitude speleothem record of millennial-scale climatic variability during OIS3 from the Villars Cave that, combined with former published contemporaneous samples from the same cave, gives a coherent image of the climate variability in SW-France between ~55 ka and ~30 ka. The 0.82 m long stalagmite Vil-stm27 was dated with 26 TIMS U-Th analyses and its growth curve displays variations that are linked with the stable isotopes, both controlled by the climatic conditions. It consists in a higher resolved replicate of the previously published Vil-stm9 and Vil-stm14 stalagmites where Dansgaard-Oeschger (DO) events have been observed. The good consistency between these three stalagmites and the comparison with other palaoeclimatic reconstructions, especially high resolution pollen records (ODP 976 from the Alboran Sea, Monticchio Lake record from southern Italy) and the nearby MD04-2845 Atlantic Ocean record, permits to draw a specific climatic pattern in SW-France during the OIS3 and to see regional differences between these sites. Main features of this period are: 1) warm events corresponding to Greenland Interstadials (GIS) that are characterized by low speleothem d13C, high temperate pollen percentages, warm temperatures and high humidity; among these events, GIS#12 is the most pronounced one at Villars characterized by an abrupt onset at ~46.6 ka and a duration of about 2.5 ka. The other well individualized warm event coincides with GIS#8 which is however much less pronounced and occurred during a cooler period as shown by a lower growth rate and a higher d13C; 2) cold events corresponding to Greenland Stadials (GS) that are clearly characterized by high speleothem d13C, low temperate pollen abundance, low temperature and enhanced dryness, particularly well expressed during GS coinciding with Heinrich events H5 and H4. The main feature of the Villars record is a general cooling trend between the DO#12 event ~45.5 ka and the synchronous stop of the three stalagmites at ~30 ka ±1, with a first well marked climatic threshold at ~41 ka after which the growth rate and the diameter of all stalagmites slows down significantly. This climatic evolution differs from that shown at southern Mediterranean sites where this trend is not observed. The ~30 ka age marks the second climatic threshold after which low temperatures and low rainfalls prevent speleothem growth in the Villars area until the Lateglacial warming that occurred at ~16.5 ± 0.5 ka. This 15 ka long hiatus, as the older Villars growth hiatus that occurred between 67.4 and 61 ka, are linked to low sea levels, reduced ocean circulation and a southward shift of the Polar Front that likely provoked local permafrost formation. These cold periods coincide with both low summer 65°N insolation, low atmospheric CO2 concentration and large ice sheets development (especially the Fennoscandian).