Abstract
Thanks to the precise core dating and the high sedimentation rate of the drilling site (Gallipoli Terrace, Ionian Sea) we were able to measure a foraminiferal δ18O series covering the last 2,200 years with a time resolution shorter than 4 years. In order to support the quality of this data-set we link the δ18O values measured in the foraminifera shells to temperature and salinity measurements available for the last thirty years covered by the core. Moreover, we describe in detail the dating procedures based on the presence of volcanic markers along the core and on the measurement of 210Pb and 137Cs activity in the most recent sediment layers. The high time resolution allows for detecting a δ18O decennial-scale oscillation, together with centennial and multicentennial components. Due to the dependence of foraminiferal δ18O on environmental conditions, these oscillations can provide information about temperature and salinity variations in past millennia. The strategic location of the drilling area makes this record a unique tool for climate and oceanographic studies of the Central Mediterranean.
Highlights
Background & SummaryKnowledge of natural climate variability is required to understand recently observed trends and to assess anthropogenic effects on climate
Marine cores with very high sedimentation rates allow for investigating climate variations on scales of decades up to millennia
For many years the Torino Cosmogeophysics group has studied sediment cores drilled from the Gallipoli Terrace in the Gulf of Taranto (Ionian Sea) and deposited in the last millennia
Summary
Knowledge of natural climate variability is required to understand recently observed trends and to assess anthropogenic effects on climate. We measured the oxygen isotope composition δ18O of planktonic foraminifera in one of the cores extracted from the Gallipoli Terrace These measurements provided a high-resolution, 2,200-year-long record (see Data Citation 1) which allowed us to demonstrate that the millennial trend and the bicentennial oscillation detected in this series are temperature driven[1]. In a recent paper[2], using these isotopic data together with historical Po River discharge data and oceanographic measurements, we have shown that the Po River discharge undergoes robust decadal fluctuations that reach the Ionian Sea, ~1,000 km south of the Po River delta, by salinity anomalies propagation These salinity variations have been registered in the foraminifera shells[3,4] and allowed for the first time a reconstruction of North Italian hydrological variability on millennial-scale. In the last section we give several analysis and arguments validating the data-set
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