The occurrence and role of microencruster frameworks in Late Jurassic to Early Cretaceous platform margin deposits of the Northern Calcareous Alps (Austria)

Late Jurassic reefs are generally assumed to lack “cement crusts”. In the present paper, microencruster frameworks with variable amounts of cement are described from Late Jurassic to Earliest Cretaceous shallow-water carbonates of the Northern Calcareous Alps of Austria. The boundstones are characterized by a specialized and highly diverse community of microencrusters, partly occupying cryptic habitats. Volumetrically of minor importance compared to similar Permo-Triassic examples, Late Jurassic to Earliest Cretaceous microframeworks here reported compare well with cement reefs or cement-supported counterparts of other time intervals. The assumed depositional setting is that of a fore-reef slope environment. Generally, this peculiar microfacies can be integrated in current concepts of Late Jurassic reef classifications. Although more details are still needed for comparison, Late Jurassic microencruster-cement frameworks seem to be typical, but not restricted to the margins of Neotethyan isolated platforms.