Tortonian - early Messinian carbonate ramp development in the Paleoadriatic domain, the role of Mediterranean evolution on carbonate factory and facies belt: insight from the Lithothamnion Limestone (Majella, Central Apennines, Italy)

The Lithothamnion Limestone constitutes the uppermost, shallow-water unit of the Bolognano Fm. The latter represents the northern sector of Apulian Carbonate Platform developing in the central Mediterranean domain (Paleoadriatic domain), cropping out in the Majella Mountain (Palena, Central Italy). The profile is consistent with a homoclinal carbonate ramp, with a wide middle ramp in which coralline algae, mainly forming the marl facies, dominated the carbonate production. The outer ramp, in the aphotic zone, was characterized by bioturbated hemipelagic marls with planktonic foraminifera and pectinids. The inner ramp was widely colonized by seagrass meadows interfingering with the marl facies of the middle ramp. The main biota producing carbonate sediments of this vegetated area were benthic foraminifers (mainly porcelaneous foraminifers) and red algae, together with abundant serpulids. The shallowest facies of the inner ramp are represented by oolitic shoals and coral buildups generally encrusted by serpulids and red algae. This ramp developed during the late Tortonian to early Messinian interval, when coral reef complexes abundantly developed in Mediterranean. In this work, we analyse and evaluate the environmental conditions that prevented the development of coral reefs in the Paleoadriatic domain. Geochemical and compositional analyses point towards the deterioration of trophic and, more in general, environmental conditions, coinciding with a strong increase of terrigenous input, organic matter and reducing trace elements. This change coincides with climatic changes induced by precessional forcing starting at 7.1 Ma due to the progressive closure of the connection with the Atlantic Ocean in the Rifian corridors. In this context, the terrigenous sedimentation in the Adriatic foredeeps, related to the Apennine evolution during the early Messinian, could have contributed to amplify the progressive deterioration of environmental conditions in the basin.