Climate variability during MIS 20–18 as recorded by alkenone-SST and calcareous plankton in the Ionian Basin (central Mediterranean)

Paleoproductivity Modes in Central Mediterranean During MIS 20—MIS 18: Calcareous Plankton and Alkenone Variability

“…The occurrence of G. bulloides (Figure 3h) is consistent with nutrient availability in surface water related to wind-induced vertical mixing during cold and arid climate, while the presence of N. pachyderma (Figure 3i) suggests polar-subpolar water incursion into the Mediterranean (Cacho et al, 1999;Capotondi et al, 2016;Girone et al, 2013;Marino et al, 2018;Pérez-Folgado et al, 2003;Sierro et al, 2005) and at the site location. Both marine and continental proxies support colder-drier conditions during MIS 20 in the IS (Figure 1C; Bertini et al, 2015;Maiorano et al, 2016;Marino et al, 2020;Nomade et al, 2019), which are likely related to enhanced north-westerly winds, adequate mixing and nutrient availability in surface water. Despite the flourishing of the highly productive small Gephyrocapsa group (Figure 2d), Total N, C 37 and C 37:2 /C 38:2 indicate that coccolithophore productivity in surface waters remains rather low during this phase (Figures 3b, 3d and 3e), with respect to other periods.…”

“…For this work, we used the Müller et al (1998) calibration to translate U k' 37 to SST. The whole alkenone-based SST record (Figure 2b) is already presented in Marino et al (2020) and thus not introduced in the following result section. However, in Table S1, we also supply the Bayesian estimate and arguments (Text S1) for choosing the Müller et al (1998) calibration.…”

“…Our study aims to fill the gap of knowledge that exists on the productivity variations during the Early/Middle Pleistocene period in the central Mediterranean region, focusing across the interval from the late Marine Isotope Stage (MIS) 20 to the MIS 18 glacial inception. This interval includes MIS 19, considered a close analog of the present interglacial (Pol et al., 2010; Tzedakis et al., 2012) and which revealed orbital and millennial‐scale climate variability in marine (Emanuele et al., 2015; Ferretti et al., 2015; Maiorano et al., 2016; Marino et al., 2020; Nomade et al., 2019; Sánchez Gõni et al., 2016; Toti et al., 2020; Tzedakis et al., 2012), lacustrine (Giaccio et al., 2015; Mangili et al., 2007; Regattieri et al., 2019), and ice core (Pol et al., 2010) records. We have investigated the expounded marine Ideale section in southern Italy (Figures 1A–1C), which is part of the Montalbano Jonico sequence (MJS, southern Italy) encompassing MIS 37‐MIS 16.…”

“…Figure 2. Benthic oxygen isotope (a) fromNomade et al (2019) and alkenone-sea surface temperature (SST) records (b) fromMarino et al (2020) are compared with absolute (c) and relative (d)-(h) coccolithophore abundance at the Ideale section. Reworked coccolith taxa (i) are also shown and compared with paleodepth profile (j) at Ideale section (IS)(Stefanelli, 2003) and global sea level reconstruction plotted as sea level equivalent (m relative to modern) (k) fromElderfield et al (2012).…”

“…Figure 3. Carbon isotope record (a) from Nomade et al (2019) compared with alkenone C 37:2 /C 38:2 (b) and C 37 patterns (d), coccolithophore relative (c) and absolute (e) abundances, dissolution index (f) and species dominance (g).Globigerina bulloides and polar-subpolar Neogloboquadrina pachyderma patterns at the Ideale section (h)-(i) are fromMarino et al (2020). Precession and insolation curves (j) are according toLaskar et al (2004).…”