The depositional architecture of Latemar and Sella, isolated Triassic microbial platforms of the Dolomites, NE Italy

Microbial carbonate platforms are common in the Pre-Cambrian and most of the Phanerozoic, often hosting hydrocarbons, but since they are distinct from modern coral reefs or skeletal carbonate ramps, a standardised facies model for such microbial-dominated carbonate bodies is still missing. The reconstruction of the stratigraphic architecture of these types of depositional systems must often rely on investigation of outcrop analogues. The authors propose herein a 2 day field itinerary in which depositional features, depositional geometries and facies architecture of two Triassic microbial carbonate platforms of the Dolomites (Southern Alps, NE Italy) will be presented at key outcrops and discussed. The Dolomites host a variety of Triassic carbonate platforms of this type. They are characterised by high relief and steep slopes and have been studied as analogues to Palaeozoic and Mesozoic hydrocarbon reservoirs such as those of Central Asia, Central America, northern Russia or North America, with which they share significant similarities. In this guide, two excursions are described and focus on the upper Anisian (Middle Triassic) Latemar and the lower Carnian (Upper Triassic) Sella; two examples that are particularly suitable for directly appreciating and understanding architecture and facies characteristics of such microbial sedimentary units because of their limited size and excellent exposure. Easy accessibility makes it possible to examine several key features through a short visit, with only minor safety issues. The Latemar platform has escaped pervasive dolomitization, so that sedimentary facies are very well preserved. Furthermore, the Sella and the Latemar crop out perfectly, exposing the depositional geometries and their lateral facies relationships with coeval deep-water basins at seismic scale. The proposed field itinerary is aimed at geologists, either from industry or from academia, who have interest in microbial carbonate platforms, wish to learn sequence stratigraphy in the field and to look at outcrop analogues of carbonate depositional systems as seen in seismic surveys.