Central Mediterranean progressive isolation and climate change from Tortonian to early Messinian: Insight from hemipelagic successions of Central Apennines (Central Italy)

Progressive isolation of the Mediterranean basin began significantly before the onset of the “Messinian Salinity Crisis” and gypsum deposition. During this subtropical interval, detrimental conditions for benthic and phototrophic fauna occurred, affecting different sub-basins and depositional environments. To identify the progressive closure and the consequences of the restricted circulation within the Central Mediterranean, this study analyses the δ 18 O and δ 13 C records of Orbulina specimens of two Tortonian-Messinian hemipelagic successions, constrained by calcareous nannofossil biostratigraphy and belonging to the Latium-Abruzzi and the Apulian Domains (Central Apennines, Central Italy). During the Late Miocene, the Latium-Abruzzi Domain became a deep basin due to the transition from a foreland to a foredeep system. Conversely, the Apulian Domain remained a relatively shallow, undisturbed foreland basin throughout the interval of interest. δ 18 O and δ 13 C records -analysed on isolated specimens of planktonic Orbulina foraminifer- attest a humid peak in the Tortonian (8.5 Ma), where a major freshwater input entered in the Latium Abruzzi basin during a Washhouse Event. Then, in late Tortonian to early Messinian, local controlling factors progressively influenced water chemistry and circulation of both the basins. Freshwater and organic matter inputs increased due to the enhanced runoff. Such a strong influence of local runoff places the beginning of progressive isolation for the investigated Central Mediterranean sub-basins, as well as the onset of environmental stress on complex ecosystems, close to the Tortonian-Messinian boundary.