Resumen de A Late Ordovician sea–level curve for the Central Oslo Region: implications for Ashgill correlations
Arne Thorshøj Nielsen, David A.T. Harper
The construction of regional sea–level curves provides a powerful tool to effect intra–provincial correlations. The analysis of sea–level fluctuations can, however, also aid the development of bio– and lithofacies models and help predict both short and long–term environmental change. The Oslo Region is one of the classic areas of Ordovician geology with abundant and diverse fossils developed across a wide range of facies. A modern lithostratigraphy is available for the region (Owen et al., 1990); that together with a robust biostratigraphy based on nearly 200 years of research provides a frame for the further investigation of biotic and environmental change. The well–exposed and fossiliferous rocks of the region provide an ideal opportunity to develop a sequence stratigraphy, particularly in the variable lithofacies of the Upper Ordovician. A model involving five major drowning events, the Linearis–1, Spannslokket, Husbergøya, Langøyene and Sælabonn, is outlined for the uppermost Caradoc–Ashgill deeper–water facies of the central Oslo Region. Extrapolation of the model north and west to the Ringerike, Hadeland and Mjøsa districts has provided a modified template for upper Ordovician correlations within and possibly outwith the region.
