BIOSTRATIGRAFIA ED EVOLUZIONE PALEOGEOGRAFICA DEL MESOZOICO DELL'AREA DEL MONTE CAIRO E DI VALLEROTONDA (LAZIO MERIDIONALE, ITALIA) (***)

Abstract

The results are presented of biostratigraphic studies and analyses carried out on twelve Mesozoic successions cropping out in the Monte Cairo area and in that bordering on Vallerotonda in southern Latium. In the fo1mer area, a small portion of the carbonate sedi­ments can be referred to Dogger and mainly to Malm-Senonian. The carbonate sedimentation is affected by two stratigraphic unconforrnities, the first of which, extending from the end of early Albian to a considerable part of early Cenomanain and evidenced by a consistent bauxite deposit (bxl), can be ascribed to the sedi­mentary tectonics that deterrnined the emergence of the area and its consequent karstification. This is a regional event but one which, more generally, affected various areas of Tethys (Greece, the outer and inner Dinarides, etc.). The second unconformity, evidenced by one or more thin layers of calcareous breccias with reddish cement (bx2), mostly extends from Turonian and can in all probability be ascribed to bathymetric variations. [...]