Fig. 2.

Core chronology, geochemistry, and mineralogy. (A) Geochemistry and mineralogy. LOI at 550 °C/1000 °C; profile of Na/Ca ratios; and major authigenic minerals (excluding clays, quartz, and feldspar) determined by X-ray diffraction (minerals are ordered from left to right to reflect generally higher salinities). (B) Bayesian chronological model. 1, Excluded ¹⁴C date that fails to follow a monotonic ordering; 2, excluded ⁴⁰Ar/³⁹Ar date from a single crystal. Two chert dates from samples later found to contain secondary chalcedony were also excluded from the model. See SI Appendix for details.