Figure F4. Pore-water strontium isotopic composition plotted as a function of reciprocal strontium concentration. The linear array for each drill site indicates that most of the variation of strontium isotopic values result from mixing between two distinct sources: a low strontium concentration end-member with modern seawater-like characteristics (⁸⁷Sr/⁸⁶Sr = ~0.7092) and a high concentration end-member with either a late Eocene-age (Sites 1050 and 1052) or mid-Cretaceous-age (Site 1052) source with ⁸⁷Sr/⁸⁶Sr values at ~0.70774 and ~0.70734, respectively.