Browsing by Author "Antonioli, F"
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- ItemPhasing and amplitude of sea-level and climate change during the penultimate interglacial(Nature Publishing Group, 2009-05) Dutton, A; Bard, E; Antonioli, F; Esat, TM; Lambeck, K; McCulloch, MTEarth's climate has oscillated between short-lived interglacial and extended glacial periods for the past million years. Before the last interglacial, absolutely dated markers of sea level become increasingly rare; hence, our knowledge of sea-level change driven by the waxing and waning of continental ice sheets before that time is largely based on proxy records from deep-sea cores(1-3) that lack direct age control. Here we present precise U-Th ages for a remarkable collection of submerged speleothems(4,5) from Italy, which record three sea-level highstands during the penultimate interglacial period, Marine Isotope Stage 7, from 245,000 to 190,000 years ago. We find that sea level rose above-18m (relative to modern sea level) several thousand years before maximum Northern Hemisphere insolation during the first and third highstands. In contrast, the second highstand, Marine Isotope Stage 7.3, is essentially synchronous with the insolation maximum, and sea level during this highstand only peaked at about 18 m, even though the concurrent insolation forcing was the strongest of the three highstands. We attribute the different phasing and amplitude of the Marine Isotope Stage 7.3 highstand to the extensive continental glaciation that preceded it. This finding highlights the significance of cryosphere response time to the climate system. © 2009, Nature Publishing Group.
- ItemUplift rates defined by U-series and C-14 ages of serpulid-encrusted speleothems from submerged caves near Siracusa, Sicily (Italy)(Elsevier, 2009-02) Dutton, A; Scicchitano, G; Monaco, C; Desmarchelier, JM; Antonioli, F; Lambeck, K; Esat, TM; Fifield, LK; McCulloch, MT; Mortimer, GEWe have established a plausible rate of uplift near Siracusa in southeastern Sicily (Italy) over the last glacial-interglacial cycle using U-series ages of submerged speleothem calcite and C-14 ages of calcite serpulid layers that encrust the speleothems during cave submergence. The precisely determined ages of these sea level benchmarks were compared with expected relative sea level position based on glaciohydro-isostatic modeling to assess the rate of uplift in this region. When combined with the age of various late Holocene archaeological sites that have been recently described and characterized in terms of their functional position relative to sea level these data collectively define a rate of uplift <= 0.4 mm a(-1) along this portion of the Sicilian coastline. These results are consistent with an age assignment of marine isotope stage (MIS) 5.3 or 5.5 for the Akradina terrace. which in turn places temporal constraints on paleoshorelines above and below this level. © 2008, Elsevier Ltd.