Superposition and Intra-Stratal Bedding: Comparing the effects of different diagenetic models on stratigraphy.

The principles of stratigraphy, rooted in the foundational works of Nicolaus Steno, William Smith, and Johannes Walther, assert that sedimentary layers are deposited sequentially and preserve a temporal and environmental record. While these principles have guided stratigraphic interpretation for centuries, carbonate successions challenge their straightforward application due to the impact of diagenetic processes. This was clear to earlier work on diagenetic bedding by e.g. Robin Bathurst or Werner Ricken, who discussed the implications for their models. More recent work on early diagenetic transformations, including dissolution, cementation, and differential compaction, can modify or completely obscure primary depositional features, resulting as well in a specific type of secondary “diagenetic bedding,” introducing intra-stratal lithological patterns that mimic primary bedding but are unrelated to depositional events.Here we compare the mechanisms behind a variety of types of diagenetic bedding, with a focus on their implications for stratigraphy, paleoenvironmental reconstruction, and geochronology. We demonstrate how secondary features can disrupt traditional stratigraphic assumptions, obscure temporal resolution by combining distinct depositional layers into single beds or splitting original layers into multiple diagenetic units, and explore how differential preservation of aragonitic and calcitic components introduces spatial and temporal variability in fossil records, potentially disrupting correlations across stratigraphic sections. We summarise for the individual diagenetic models the key features to identify diagenetic bedding and the potential implications for stratigraphic applications.