Long-term (10(5)) or short-term (10(3)) delta C-13 excursion near the Palaeocene-Eocene transition: Evidence from the Tethys

Expanded sedimentary records from the Tethys reveal unique :faunal and isotopic changes across the Palaeocene-Eocene (P-E) transition. Unlike in the open oceans, the Tethys exhibits a gradual decrease of 1.5 parts per thousand in delta(13)C values prior to the rapid delta(13)C excursion. Associated with the delta(13)C excursion is a decrease in calcite burial, increase in detrital content and appearance of a unique opportunistic planktic foraminiferal assemblage (e.g. compressed acarininids). The existence of a prelude decrease in delta(13)C values in the Tethys suggests that the P-E delta(13)C excursion may have occurred in two steps and over a few hundred thousand years, rather than as one step over a few thousand years as previously suggested. This slower excursion rate is readily explained by changing organic carbon weathering or burial rates and avoids the need of invoking ad hoc scenarios.