Direct Dating of Pliocene Sea-Level Stands from Western Mediterranean

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Conference Proceeding

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Throughout most of the Pliocene the atmospheric CO2 concentration was as high or even higher than today, and temperatures on Earth were above the preindustrial ones by as much as 4ºC. Since parts of the Greenland and the Antarctica ice sheets were not present, global mean sea level must have been higher than it is today. If a link between global ice volume, sea level, and CO2 concentration exists as suggested by recent studies, then the early to middle Pliocene climates are important for interpreting the path of future climate warming. Repeated hydro-and glacio-isostatic-triggered sea-level oscillations left distinct horizons of calcite oraragonite phreatic cover growths on speleothems (POS) at different elevations in the coastal caves of Mallorca Island, western Mediterranean. Here we present the first absolute U-Pb Pliocene ages of POS from a littoral cave in the northeastern part of the island. A key aspect of our results is the robust absolute chronology and the precise elevation of the POS. The six distinctive POS horizons extending between 22.5 and 32m above present sea-level (mapsl) provide evidence of the behavior of relative sea-level during the Pliocene. The oldest sea-level stand at +32 mapsl yielded an age of 4.39±0.39 Myr, whereas the youngest one formed 3.27±0.12 Maat 23.5 mapsl. These results represent the first U/Pb dated snapshots into the early to middle Pliocene sea-level variability. We will present on going work that considers the contribution of glacial isostatic adjustment and dynamic topography to the elevation of the POS in order to relate local sea level to the global mean. Our results suggest that the peak Pliocenesea-level high stand might have been prior to the mid-Pliocene Warm Period.

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Citation / Publisher Attribution

PALSEA-QUIGS: Climate, Ice Sheets and Sea Level during Past Interglacial Periods, p. 32