IL Membro di Dogna: Istituzione dell'unità litostratigrafica e definizione della paragenesi

This work deals with the Julican (Carnian) unit so far informally called Dogna “formation”. This latter is a terrigenous-carbonate unit that crops out in the Carnian Alps (Italy). It represent environments of inner ramp and lagoon with arenitic/oolitic bars of delta front and tabular bodies of dolomite deposited in a evaporitic-arid setting. Facies analysis was conducted on the carbonate facies in order to determine the depositional environments and to put forward a formal proposal for the institution of the Member of Dogna. A study of the paragenesis was carried out on the carbonates of the unit with optical microscopy and in cathodoluminescence, that allowed the identification of various phases of cements and diagenetic alteration processes. The petrographic study was then integrated with carbon and oxygen isotopic data on carbonate. As the Member of Dogna is coeval with a episode of humid climate called "Carnian Pluvial Event" (CPE), the isotopic analyses were also used to identify a possible isotopic oscillation. However, the isotopic composition of carbonate revealed to be too altered by diagenesis to record any environmental variations of the carbon isotope ratio.