Ir anomalies and other elemental markers near the Palaeocene–Eocene boundary in a flysch sequence from the Western Tethys (Slovenia)

Ir abundance anomalies, platinum-group elements (PGE) enrichment and increased concentrations of meteoritic (Ni, Fe, Co) and nonmeteoritic (Sb, As, Zn and Cu) elements were found in the Palaeocene–Eocene (P/E) boundary interval in a flysch sequence from the Western Tethys (Goriška Brda section, W. Slovenia). This records one of the most important calcareous deep benthic extinctions in the history of the Earth. Although the observed geochemical patterns could indicate complex sources for these metals, such as weathering of the continental and oceanic crust, volcanic processes, as well as diagenetic mobilization and redistribution, we cannot preclude the highly speculative possibility that the observed Ir abundances may also indicate extraterrestrial contamination.