A tsunami deposit at the Cretaceous-Tertiary boundary in the Neuquen Basin of Argentina.

SCASSO, R.; CONCHEYRO, A.; KIESSLING, W; ABERHAM, M; HECHT, L.; MEDINA, F.; TAGLE, R.

CRETACEOUS RESEARCH (PRINT)

Elsevier

Lugar: Amsterdam, Holanda; Año: 2005 vol. 26 p. 283 - 297

0195-6671

A coarse-grained sandstone bed of Cretaceous/Paleogene (K/Pg) boundary age occurs in a homogeneous neritic shelf mudstone sequence (Jagu¨ el Formation) in the Neuque´n Basin of Argentina. This bed, 15e25 cm thick, contains abundant plagioclase, broken shells and sharks? teeth. Sedimentological features include an erosive base, abundant rip-up clasts, normal grading and hummocky cross-bedding. The K/Pg boundary age of the bed was confirmed by calcareous nannofossils. Similar to other sections in the Gulf Coast region and the Danish Basin, a ??dead zone?? significantly depleted in macrofossils is evident in the basal 1 m above the clastic layer. In combination, these features suggest that the clastic layer represents a tsunami deposit that was related to the Chicxulub impact event in Yucatan/Mexico. Mechanisms of tsunami wave amplification in this extremely distal and somewhat protected setting are poorly understood but the funnel-shape of the basin may have promoted the unusually strong sedimentological response.