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Research Article
INTRODUCTION
Precise age models are of paramount importance for paleoclimatic and paleoenvironmental reconstructions based on marine sediment cores. This is especially true when correlating signatures of climate oscillations to external forcing mechanisms such as solar irradiance or Milankovitch cycles. Tephrochronostratigraphy is an effective dating method because ash layers can be cross-correlated between all types of sedimentary environments including terrestrial, marine, and lacustrine archives (e.g., Keller et al., 1978; Paterne et al., 1986; Wulf et al., 2004; Kutterolf et al., 2008, 2016; Neugebauer et al., 2017). Furthermore, in the Mediterranean, tephroanalysis on historical time scales bears minimal temporal uncertainty compared with other common dating methods (accelerator mass spectrometry [AMS]14C dating), because historic documentation exists for major eruptions of the past ~2000 yr (e.g., Arnò et al., 1987). The Gulf of Taranto provides an ideal setting for high-resolution paleoclimatic studies (Taricco et al., 2008, 2009, 2015; Zonneveld et al., 2012; Goudeau et al., 2013, 2014) because it is especially susceptible to both climate variability and human-induced changes in land use, eutrophication, and pollution on the Italian mainland. High amounts of nutrients and suspended sediments from the Po and other Italian rivers are transported northwest to southeast along the Adriatic coast and result in unusually high sedimentation rates in the Gulf of Taranto. Its location downwind of the highly explosive Italian volcanic province suggests the use of tephrostratigraphy to accurately date marine sediment cores (Fig. 1C). Several eruptions of Mt. Vesuvius, the Phlegrean Fields, the Eolian Islands, and the Palinuro seamount have emplaced pronounced distal tephra layers in this region (e.g., Siani et al., 2004; Wulf et al., 2008). However, in contrast to thick ash deposits from the eastern Mediterranean Sea that are identifiable by distinct color and grain-size changes (e.g., Guichard et al., 1993; Kuzucuoglu et al., 1998; Wulf et al., 2002), there are no macroscopically visible tephra layers in the uppermost sediments of the Gulf of Taranto most likely because there were no eruptions during the past several hundred years that were strong enough to transport large amounts of pyroclasts (e.g., Goudeau et al., 2014; this study). Macroscopic tephra recognition in distal marine or lacustrine sediments as well as soils and ice...