Studio stratigrafico e strutturale delle successioni triassiche con piattaforme saldate e realizzazione di una carta geologica 1:10.000 dell'area del Vallon Popera

Abstract

The stratigraphic sequence outcropping in Vallon Popera area (Eastern Dolomites) differs from the classical stratigraphic column knowns of the Dolomites, because carbonate platforms are amalgamated. The area is characterised by facies related to different depositional environments. Starting from Lower Anisian it is possibile to recognize a sabkha environment (Lusnizza Fm) followed by an alternation of shelf and deep ramp deposits (gracilis Fm and Calcari Scuri del Coll’alto). On top of these ramp deposits two kinds of microbial carbonate platforms (Monte Rite Fm; Upper Serla Fm) began to grow. These platforms can either be welded each other or separated by basinal deposits (Dont Fm). Locally (Selvapiana massif), a peculiar facies of Richthofen Conglomerate can be found on top of the Upper Serla Fm. In the whole area, terrigenous–carbonate deposits (Morbiac Limestone) overlie the Upper Serla Fm, which in turn is followed by platform (Contrìn Fm) or basinal (Moena Fm) deposits. Locally, the Livinallongo Fm overlies either the Moena Fm or the Contrin Fm, that in turn are followed by Sciliar Fm. thick carbonate platform. A Carnian carbonate platform overlies the Sciliar Fm (Cassian Dolomite). The boundaries between Monte Rite Fm and Upper Serla Fm, Contrin Fm and Sciliar Fm, and Sciliar Fm and Cassian Dolomite, are marked by subaerial exposure surfaces, easily recognisable the in field because of the red colouration. These stratigraphic successions were involved in two main deformational phases. The first is related to the Anisian sinsedimentary extensional tectonics and the second to the following Alpine compression. This polyphasic deformation resulted in large scale a flower negative structur