The Late Triassic cherty dolostones of M. Marrone (Mainarde range) as part of the Molise basin.

The stratigraphic succession of Mt. Marrone (Mainarde range - southern part of the Abruzzi National Park) starts with thin bedded cherty dolostones, suggesting deposition in a pelagic basin; radiolarians indicate a Late Triassic age. These dolostones are similar to the cherty dolostones of the Frosolone 2 well (Molise basin). The cherty dolostones of Mt. Marrone are followed by massive and nodular dolostones of proximal basin environment. Partially dolomitized nodular limestone, with radiolarians and thin shelled pelecypods, overlies the massive dolostones. The upper part of the succession contains radiolarites, calcirudites, shales and cherty calcarenites; its age is Barremian-Aptian. Many pebbles in the calcirudites come from a shallow water carbonate platform, a minor amount being of basinal facies; their ages span from Dogger to Early Cretaceous. Their presence suggests the occurence of synsedimentary (extensional) faulting. The close resemblance between the Mt. Marrone succession and the Molise successions of the Frosolone 2 well and of Pesche (Isernia) suggests that the whole Mainarde range belonged to the Molise basin. The Late Triassic age of the cherty dolostones clearly point out the different origin of the Molise basin (with pelagic facies since the Late Triassic) with respect to the Umbria-Marche basin, with its southern prolongation in the Mt. Genzana-Mt. Greco range, which shows pelagic facies starting from the Middle Liassic.