Facies and stratigraphic architecture of the Korallenoolith Formation in North Germany (Lauensteiner Pass, Ith Mountains)

During the Oxfordian, Bahamian-type shallow-water carbonates formed in the Lower Saxony Basin of North Germany. The outcrop of the Korallenoolith Formation in a quarry in the Ith Mountains (Lauensteiner Pass) contains a series of well-exposed coral and coral-microbial reefs intercalated with oolites. Six different facies are distinguished, which can be assigned to the inner part of a carbonate ramp. Based on textural variations and facies stacking patterns, accommodation space to sediment supply and/or sediment production cycles of different hierarchies were defined in this succession. A multispectral outcrop gamma-ray log was measured as additional tool to separate facies and to identify the cyclicity. A good correlation between fluctuations in the gamma-ray log and the lithological changes exists. Generally, coral and coral-microbial reefs reflect times of higher available accommodation space, oolites indicate sedimentation in shallower waters. We thus show how, based on sequence stratigraphy, the succession of the Korallenoolith Fm can be subdivided into genetic packages. This approach may contribute in providing a tool for a firm high resolution correlation of the different outcrops of this formation, which is presently only poorly constrained. The good correlation between gamma-ray log and the cyclicity may also be helpful for subsurface correlations in the Lower Saxony Basin.