Publisher © Czech Geological Survey, ISSN: 2336-5757 (online), 0514-8057 (print)
Carbon isotope evidence for the Valanginian anoxic event in the Silesian unit
Abstract
Stable carbon and oxygen isotopes were studied in the zone of natural outcrops of Lower Cretaceous (Late Valanginian-Early Hauterivian) sediments of the Silesian Unit on the Czech territory (Outer Western Carpathians) in the Morávka River by Skalice. Increased 813C value in the Late Valanginian can be correlated with that from other sections of the Tethyan realm. The values of 813C increased significantly from a level of 0.43 or 0.75 %0 to 1.81 %0. The change in isotopic (813C and 818O) record could be connected with an intensified freshwater input into the ocean (increase of terrestrial palynomorphs input) in the Late Valanginian. The increase of organic matter storage is connected with the dark grey claystones sedimentation.
