Rotzo Formation
The Rotzo Formation (also known in older literature as the Noriglio Grey Limestone Formation) is a geological formation in Italy, dating to roughly between 189 and 183 million years ago and covering the Pliensbachian stage of the Jurassic Period in the Mesozoic Era. Has been traditionally classified as a Sinemurian-Pliensbachian Formation, but a large and detailed dataset of isotopic 13C and 87Sr/86Sr data, estimated the Rotzo Formation to span only over the whole Pliensbachian. The Rotzo Formation represented the Carbonate Platform, being located over the Trento Platform and surrounded by the Massone Oolite (marginal calcarenitic bodies), the Fanes Piccola Encrinite (condensed deposits and emerged lands), the Lombadian Basin Medolo Group and Belluno Basin Soverzene Formation (open marine), and finally towards the south, deep water deposits of the Adriatic Basin. The also Pliensbachian Aganane Formation of Morocco represents a regional equivalent, both in deposition and faunal content.
| Rotzo Formation | |
|---|---|
| Stratigraphic range: Early-Late Pliensbachian ~ | |
The Cimon del Latemar represents the internal lagoon of a fossil carbonate platform | |
| Type | Geological formation |
| Unit of | Calcari Grigi Group |
| Sub-units | Tovel Member |
| Underlies | Calcari Grigi di Noriglio Formation |
| Overlies | Monte Zugna Formation |
| Lithology | |
| Primary | Lagoonal or restricted shallow subtidal; lithified, gray, silty marl. Paralic; ooidal, gray grainstone and bioturbated, intraclastic, ooidal, gray wackestone. Subtidal flat with mud banks and sand deposits. |
| Other | Light-grey to yellowish-grey packstone, with oolites, bioclasts, algal lumps, pellets, dasycladacean algae, foraminifera, lituolids, and miliolids |
| Location | |
| Location | Vicenza Province: Trentino-Alto Adige, Southern Alps |
| Coordinates | 45.7°N 11.1°E |
| Approximate paleocoordinates | 32.1°S 16.7°E |
| Region | Veneto |
| Country | Italy |
| Type section | |
| Named for | Rotzo |
Rotzo Formation (Italy) | |
Fossil prosauropod tracks have been reported from the formation. This formation was deposited within a tropical lagoon environment, similar to modern Bahamas which was protected by oolitic shoals and bars from the open deep sea located to the east (Belluno Basin) and towards the west (Lombardia Basin). It is characterized by a rich paleontological content. It is notable mostly thanks to its great amount of big aberrant bivalves, among which is the genus Lithiotis, described in the second half of the nineteenth century. The unusual shape of Lithiotis and Cochlearites shells, extremely elongated and narrow, characterized by a spoon-like body space placed in a high position, rarely preserved, seems to suggest their adaptation to soft and muddy bottoms with a high sedimentation rate. The Bellori outcrop displays about 20 m of limestones with intercalated clays and marls rich in organic matter and sometimes fossil wood (coal) and amber. The limestones are well stratified, with beds 10 cm to more than one metre thick, whereas the clayey levels range between 3 and 40 cm in thickness.