ALBERT

Description: The Kälberstein quarry at Berchtesgaden exposes Carnian-Norian deeper-water Hallstatt limestones. Conodont biostratigraphy, microfacies and stable isotopes of bulk carbonate matrix were investigated. The biostratigraphic results demonstrate a complete succession from the latest Carnian (Tuvalian 3/I) to the late Norian (Sevatian 2). As expected from the periplatform setting of the Hallstatt Zone, calculated mass accumulation rates conform partly to prograding sequences observed on the contemporary Dachstein platform. However, discrepancies exist, mainly for the middle Norian, pointing to an incomplete knowledge of the platform sequences. The sequence stratigraphic framework based on platform data should be complemented with data from the periplatform Hallstatt Zone. Diagenetic alteration of the limestones from Kälberstein quarry is low with a conodont alteration index (CAI)=1.0 throughout the section. Oxygen isotope values ranging from ± 1.2 to + 0.1½ (VPDB) point to stabilization and cementation at very shallow burial depths in contact with seawater in a deeper-water environment. Carbon isotope values display a clear stratigraphic trend with a rapid increase from 3.6 to 4.1½ (VPDB) during the basal Norian (Lacian 1), high values up to 4.2½ during the Lacian 2, and a slow decline starting in Lacian 3 to 2.6½ at the end of the Norian (Sevatian 1±2). These trends are best explained by variations in the global organic carbon/carbonate burial ratio with maximum organic carbon burial during the middle Lacian.