DOLOMITES - Annexes 2-8 - Provincia di Udine

NOMINATION OF THE DOLOMITES FOR INSCRIPTION ON THE WORLD NATURAL HERITAGE LIST UNESCO
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controlled by extensional faults, sometimes perfectly preserved, in the final stage of the Triassic two
rapidly sinking areas formed, to the east and west of present-day western Dolomites. In these areas
(western Trentino to the west and Schiara/Talvena - Dolomiti d’oltre Piave-Dolomiti Friulane towards
the east) they successively went on to form the Lombardy Basin and the Belluno Basin respectively
(Winterer & Bosellini, 1981). At the end of the Norian, the extensional tectonics underwent
an acceleration that led, during the Rhaetian, to a significant regression of the carbonate platform
and to a deepening of the basins. Towards the west (Dolomiti di Brenta) the greater subsidence during
the Rhaetian stage led to the deposition of strong calcareous shale sediments (Riva di Solto Shale,
Zorzino Limestone), followed by marly calcareous successions (Zu Limestone). The climate here was
generally more humid and fine terrigenous deposits can be observed. In the western Dolomites, the
sediments from the Rhaetian period (through the presence of Triasina hankteni and Aulotortus sp.)
continued instead to be typical of a shallow-water plain (Dachstein Limestone), characterized by a
mainly subtidal platform sedimentation. Characteristic of this stratigraphic interval are the calcareous
(from wackestone to packstone) banks with bivalves, among which are large Megalodontids and
Dicerocardium with dimensions even greater than 15 centimeters, and the small coral patch-reefs
(Thecosmilia sp.) (Casati et alii, 1981), characterize this period.
Megalodon and Stromatolites of the Dolomia Principale