A revised Pliocene record for marine-87Sr/86Sr used to date an interglacial event recorded in the Cockburn Island Formation, Antarctic Peninsula

We present a revised 87Sr/86Sr-curve for marine-Sr in the interval 2.5–4.5 Ma using analysis of Orbulina universa from the Middle Pliocene type section in Sicily (Punta Piccola section) and a mixed assemblage of planktonic foraminifera from ODP Site 758A and B. The new calibration is used, together with new 87Sr/86Sr analysis of pectenid calcite from Cockburn Island, Antarctica, to confirm an age of 4.7 Ma for the pectenids of the Cockburn Island Formation (formerly the Pecten Conglomerate), a unit important in marking a period of warmth and possible glacial retreat in Antarctica. Finally, to aid interlaboratory comparison of 87Sr/86Sr data, we calibrate a value of 0.709174 for EN-1 against a value of NIST 987 of 0.709248.