Iridium and other element concentrations and magnetostratigraphy across the Cretaceous/Tertiarty boundary in ODP Hole 122-761C

The sediment consists of nannofossil ooze with variable amounts of clay. The boundary is marked by a color change associated with a nearly step-like decrease of the carbonate fraction.

Paleomagnetic data and the drop of the carbonate content indicate that a strong reduction of the sedimentation rate occurred at the boundary and persisted for million of years. An iridium anomaly of 80 ng/cm**2, together with overabundances of Cr and Fe, are found in close coincidence with the planktonic crisis. These enrichments can be explained by the infall of =0.16 g/cm2 of Cl-like chondritic material.