Sedimentological-stratigraphic considerations regarding the Triassic 'reefs' of the dolomites (Italy)

Abstract

Some authors maintain that a good part of the carbonate assemblages of the Dolomites do not correspond to true 'reefs' in an ecological sense. In contrast, they suggest that these rocks belong to masses of lime mud that are part of the indented edge of a broad, shallow-water platform, the formation of which was only scarcely influenced by corals and other reef-building organisms. This hypothesis is probably correct for several carbonate bodies (i.e. Marmolada, Latemar) in which these organisms are either absent or rare. But this is not the case in other bodies where corals are abundant and are often found in growth position. It is clear that, in some cases at least, the carbonate bodies of the Dolomites correspond to true'reefs', even in an ecological sense. This is true, above all, for the dolomitic reefs of post-Ladinian age (San Cassian and perhaps lower Raiblian). It has not been demonstrated that volcanic activity in the Dolomites ceased before the San Cassian period, since a lava bank in the most elevated part of Mount Sciliar (Schlern) is included in the Rosetta dolomite, which can be referred precisely to the lower Carnian (San Cassian). According to the author the Pachycardia Formation is synchronous with the upper part of the St. Cassian Formation.