Lithostratigraphy and sedimentology across the Cretaceous/Tertiary boundary in the Flyschgosau (Eastern Alps, Austria)

Resumen

Detailed lithological profiles across the Cretaceous/Tertiary boundary (K/T) in the flyschoid Gosau Formation at Gosau (Elendgraben) and Gams (Knappengraben) are presented. The revised low sediment accumulation rates in the lowermost Danian correspond to those calculated by Smit & Hertogen (1980) for the Caravaca section. The estimated longer time-span for the deposition of the K/T boundary layers of 6-11 ka seems to be more realistic. The sediment at the K/T in the Gosau area was deposited under reducing conditions (Reissner et al. 1985). Peak levels of the siderophile elements do not coincide at Gosau and Gams. A diachronism of events is therefore assumed. The gradual decline of CaCO3 and some major element oxides beginning 4 cm below the K/T boundary and also a 1 mm thin yellow clay layer 10 mm underneath the boundary clay at Gams suggest multiple events and could be the result of a period of increased volcanism.