Geology

Simplified, North-South geologic cross-section through the Dolomites Region.Simplified, North-South geologic cross-section through the Dolomites Region.The peculiar scientific importance of the Dolomites is rooted in the uniqueness of their depositional history. These few pages try to unravel and synthesize the complexity of this geological evolution, which is however far from being fully fathomed, despite more than two centuries of research, briefly synthesised in the following chapter. The fascinating complexity of the region prompts further research, made attractive by the spectacular preservation of seismic-scale depositional geometry and sedimentary facies, framed within a bio-isotopic chronology boasting an unrivalled accuracy for the Triassic. The easily accessible region is made attractive for research also by its accurately witnessing the Permo-Triassic mass extinction, Mesozoic palaeo-biological trends, Alpine tectonic structures and Quaternary landforms. The Dolomites belong to the Alpine Chain and correspond to a comparatively gently tectonised part of the Southern Alps. This Italian portion of the Alps derived from the structural shortening of a Mesozoic passive continental margin of the Tethys Ocean. The Jurassic extensional thinning and breaking up of the continental crust were forerun by several pulses of Permo-Triassic deformation and magmatism, involving crustal structures generated by the Carboniferous Variscan Orogeny. The Middle Triassic transtensive deformation is particularly noteworthy for its casting a mark of uniqueness into the Dolomites geological landscape, by inducing fast subsidence and intense magmatism, matched with the fast growth of carbonate islands. Subsidence pulses controlled the growth of several independent carbonate platforms generations, surrounded by deep water basins, which were soon to be filled by large volumes of volcanic, volcaniclastic and terrigenous sediments. The sharp contrast between the light-coloured, carbonate platform walls and the dark-hued, basin sediment slopes provides a key contribution to both the aesthetic and scientific fascination of the mountain range. The multilingual nature of both the geological publications and the toponyms of the Dolomites region, where German, Italian and Ladin languages overlap, makes the stratigraphic terminology complex. In the following discussion, some German and Italian terms are used, without seeking any terminological exhaustivity.

Lithological sketch representing the geometric relationships between geological units in the Dolomites areaLithological sketch representing the geometric relationships between geological units in the Dolomites area