Cretaceous-tertiary boundary layer at Stevns Klint (Denmark): Copper and copper(II) porphyrins

Abstract

High concentrations (up to 4000 ppm) of copper(II) porphyrins have been detected in the kerogen of the Cretaceous/Tertiary (KT) boundary informal type sediment, the Fish Clay, at Stevns Klint, Denmark. These pigments have also been found in the Danish KT sediment at Nye Kløv, which is about 300 km away from Stevns Klint. However, copper(II) porphyrins cannot be detected in the Danich boundary rock of the Dania site, which is separated from Stevns Klint by about 200 km. It is proposed that the kerogen copper(II) porphyrins are derived from humic materials of terrestrial (peat/soil) sources already enriched with these compounds, which were redeposited in the Danish KT boundary Basin. In addition, our results show that the kerogen copper(II) porphyrins are present, for comparison, in the Permian Kupferschiefer shale from Poland. The amounts are comparable to those in the Fish Clay kerogen. To our opinion, the same processes responsible for the kerogen copper(II) porphyrin enrichment have occurred in the Stevns Klint KT boundary sediment and in the Kupferschiefer.

Keywords

• copper
• porphyrins
• kerogen
• electron spin resonance