Iridium Anomalies of Late Eocene Age at Massignano (Italy), and ODP Site 689B (Maud Rise, Antarctic)

Iridium anomalies of Late Eocene age are here reported in sequences from northern Italy and Weddell Sea, Antarctic. We have analyzed 270 samples of marly limestones from the Eocene/Oligocene boundary stratotype section at Massignano, Italy, ranging from 35.6 to 34.5 Ma (NP 18 Zone to NP 19/20 Zone). We discovered a distinct Ir peak of 156 ± 19 parts per trillion (ppt) in the lower calcareous nannofossil NP 19/20 Zone, corresponding to the mid-lower part of foraminiferal P16 Zone, and the top of magnetic Chron 16n2. The age of this Ir anomaly derived from several dated volcanic ashes found in the same section is 35.7 ± 0.4 Ma