DOLOMITES - Annexes 2-8 - Provincia di Udine
DOLOMITES - Annexes 2-8 - Provincia di Udine
DOLOMITES - Annexes 2-8 - Provincia di Udine
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NOMINATION OF THE <strong>DOLOMITES</strong> FOR INSCRIPTION ON THE WORLD NATURAL HERITAGE LIST UNESCO<br />
33<br />
Southern cliff of Mt. Rite. Wonderful outcrop of the Anisian succession<br />
The Monte Rite Formation is important from the paleoecological point of view, documenting the<br />
recovery of the bioconstructors after the biological crisis at the Permian-Triassic boundary for the<br />
first time in this stage of the Triassic Tethys, thus shifting the first occurrence of rigid-frameworks<br />
builders earlier in time by several ammonoid subzones. The Monte Rite carbonate platform is made<br />
up of alternating bioclastic calcarenites and calciru<strong>di</strong>tes with algae, bivalves and brachiopods, and<br />
light gray massive dolomites and dolomitic limestones in decimeter- to meter-thick banks, eventually<br />
amalgamated. The strata bed<strong>di</strong>ng varies from planar to slightly wavy. In the top portion of the<br />
unit there are meters-thick banks of dolomitic boundstones with encrusting organisms, Tubiphytes<br />
and Dasycladaceae algae (Physoporella pauciforata, Macroporella alpina, Diplopora sp., Aciculella sp.),<br />
with abundant vadose cements and marine phreatic ones. Very spectacular and enormous quantities<br />
of breccias and olistoliths, sometimes packed into the Dont Formation, consist of a geometric<br />
relationship with the carbonate platform containing both superimposition and lateral substitution.<br />
These breccias can be interpreted as detrital talus bo<strong>di</strong>es coeval to the platform growth and are tied<br />
to the breakdown of the platform due to submarine collapse (slides) caused by intense synse<strong>di</strong>mentary<br />
tectonics. Se<strong>di</strong>mentary <strong>di</strong>kes filled with intraclastic breccias, pelagic se<strong>di</strong>ments, and considerably<br />
thick lateral variations are documented remnants of the tectonics (Farabegoli & Guasti, 1980).<br />
The depositional environment of this unit can be referred to an open carbonate platform with sandy<br />
margins documented by cemented grainstone facies; microbialite mounds are locally recognizable<br />
that are decameters thick (Dolomiti <strong>di</strong> Braies/Pragser Dolomiten). In this time interval (between<br />
the Bythinian and the Pelsonian substages) the paleogeographic array of the Dolomites are articulated<br />
in the most complex manner with <strong>di</strong>fferent subsidence rates producing deep basins consisting<br />
of carbonate platforms. In the carbonate platform there are relatively small variations of sea level
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