The authors regret that the δ18OSO4 axis in Fig. 2 and the y axis in Fig. 6b were mislabelled in the published manuscript. In Fig. 2, the initial δ18OSO4 axis went from 17–27 and should have gone from 7–17. In Fig. 6b, the y axis went from 0–0.12 and should have gone from 0–0.06. The authors would like to apologise for any inconvenience caused. The corrected figures appear below for the reader's convenience.