Determining the way-up of the Monte Facito Formation using new sedimentological data from the "La Cerchiara" succession, Southern Apennines

The Monte Facito Formation consists of Early-Middle Triassic sediments deposited during the first stages of the continental separation of Africa and Europe. This stratigraphic unit, located at the base of the Mesozoic succession of the Lagonegro Basin, appears as a chaotic complex, severely affected by contractional tectonics, and whose original stratigraphic order is very difficult to determine. Despite these complications, a first attempt to determine stratigraphic order was performed on the southern side of the Monte Facito locality. Another key section considered was the La Cerchiara outcrop. As the Monte Facito section is no longer accessible, the La Cerchiara outcrop remains the only locality were a significant stratigraphic portion of the Monte Facito Formation can be observed. Nevertheless, the problematic way-up of the succession has until now prevented consideration of this outcrop as the main Monte Facito Formation type-succession. Difficulty in determining way-up is a consequence of a lack of high-resolution biostratigraphic dating combined with a paucity of well-preserved way-up sedimentary indicators. A detailed field survey, involving sedimentological, stratigraphic and structural observations, has been conducted with the aim of definitively understanding the correct younging direction of the Monte Facito succession exposed at the La Cerchiara locality. The recognition of well-preserved way-up sedimentary indicators, as well as graded beds and ripples, allows an eastward direction of younging to be attributed to the study succession. These results permit a better understanding of the evolution of the passive northern African palaeomargin during the Triassic period, which led to the opening of the Lagonegro Basin.