Additional file 4 of Millennial-scale oscillations in the Kuroshio–Oyashio boundary during MIS 19 based on the radiolarian record from the Chiba composite section, central Japan

Additional file 4: Fig. S2. Temporal profile of low field magnetic susceptibility and Ca/Ti. Black solid lines and circles are data from the CbCS (Okada et al. 2017; Simon et al. 2019; Izumi et al. 2021). Light blue lines are data from the TB-2 core (Hyodo et al. 2016, 2017), which was dated using the latest age model of the CbCS by Suganuma et al. (2018). The age model of the TB-2 core, which was drilled at ~ 200 m northeast from the Chiba section (Hyodo et al. 2016), was obtained by tuning the diatom assemblage record from Osaka Bay (Hyodo and Kitaba 2016; Hyodo et al. 2017), whereas the chronology of the CbCS is based on tuning the benthic foraminifera oxygen isotope record to an astronomically dated sea level record from ODP 1123 (Elderfield et al. 2012; Suganuma et al. 2018). The difference in chronology hinders comparisons of paleoenvironmental records between the CbCS and TB-2 core. To resolve this issue, we converted the depth scale of the TB-2 core to the age scale of the CbCS using the latest age model by Suganuma et al. (2018) based on correlating six tephra beds and one upper limit of the mud crust bed (Additional file 3: Fig. S1). Resultant temporal profiles of Ca/Ti ratio and low-field magnetic susceptibility of the TB-2 core show excellently synchronized variation with those of the CbCS (this S. Fig.; Hyodo et al. 2016, 2017; Okada et al. 2017; Simon et al. 2019; Izumi et al. 2021). This indicates that the tephrostratigraphic and lithologic correlation allows us to compare the paleoenvironmental records between the CbCS and TB-2 core.