Coupling of marine and continental oxygen isotope records during the Eocene-Oligocene transition

While marine records of the Eocene-Oligocene transition indicate a generally coherent response to global cooling and the growth of continental ice on Antarctica, continental rec-ords indicate substantial spatial variability. Marine Eocene-Oligocene transition records are marked by an similar to+1.1% foraminiferal delta O-18 shift, but continental rec-ords rarely record the same geochemical signature, making both correlation and linking of causal mechanisms between -marine and continental records challenging. Here, a new high-resolution continental delta O-18 record, derived from the freshwater gill-breathing gastropod Viviparus lentus, is presented from the Hampshire Basin, UK. The Solent Group records marine incursions and has an established magnetostratigraphy, making it possible to correlate the succession directly with marine records. The V. lentus delta O-18 record indicates a penecontemporaneous, higher-magnitude shift (>+1.4%) than marine records, which reflects both cooling and a source moisture compositional shift consistent with the growth of Antarctic ice. When combined with clumped isotope measurements from the same succession, about half of the isotopic shift can be attrib-uted to cooling and about half to source moisture change, proportions similar to marine forami-niferal rec-ords. Thus, the new record indicates strong hydro-logical cycle connections between marine and marginal continental environments during the Eocene-Oligocene transition not observed in continental interior records.