Biogenic burial across the Paleocene/Eocene boundary: Ocean drilling program leg 199 site 1221

The Paleocene/Eocene (P/E) boundary, at ~55 Ma, is characterized by a transient warm period lasting 10,000 yr. This interval is globally characterized by significant chemical and biological signals. Ocean Drilling Program Core 199-1221C-11X captured the P/E boundary section at a depth of 154 meters composite depth. Biogenic components of the sediment were measured across this interval in order to better define the events that occurred at the P/E boundary in the equatorial Pacific Ocean. A 26-cm interval low in CaCO₃ was identified, whereas biogenic silica and organic carbon remained unchanged. Although CaCO₃, biogenic silica, and organic carbon (C-org) production is controlled by different constraints, it is unlikely that an environmental factor would cease production by CaCO₃-producing organisms without affecting biogenic silica or C-org production. The data indicate that the CaCO₃ P/E boundary event was caused by a change in CaCO₃ preservation rather than a change in CaCO₃ production.