A possible tsunami deposit at the Cretaceous-Tertiary boundary in Pemambuco, northeastern Brazil.

Abstract

Interdisciplinary and integrated investigations of a stratigraphic succession spanning the Cretaceous-Tertiary (K-T) boundary in Pemambuco (the Poty Quarry section, near Recife), northeastern Brazil, provides direct evidence for the hypothesis of an extraterrestrial bolide impact event. Discussions on the exact position of the K-T boundary point to na impact event in the earliest Danian. One particular bed at the base of the Maria Farinha Formation shows sedimentary characteristics and exotic (probably impact-derived) material which suggest the action of a tsunami wave. The distribution of iridium concentrations throughout the studied succession records a major peak of iridium (up to 69 times the background levels) at about 15-20 cm above the main tsunami bed.