Regional and global changes around the Triassic–Jurassic boundary reflected in the late Norian–Hettangian history of the Apennine basins

摘要: Abstract Palaeogeographic restorations for the Late Triassic and Early Jurassic of west-Mediterranean area show that significant facies changes occurred in this period. The study three basinal successions Northern, Central Southern Apennines indicates ecological conditions at same time different palaeogeographic geodynamic domains. early Mesozoic evolution is controlled by opening two oceans: Ionian/East-Mediterranean Tethys to south-east Alpine Ocean north-west. Lagonegro basin, Apennines, was northern continental margin Ionian from Triassic, while La Spezia Northern became part south-eastern Middle-Late Jurassic. third studied basin (Mt. Camicia Gran Sasso, Apennines) an intra-platform Norian up late Hettangian–early Sinemurian. During Norian–Hettangian period these basins were not directly connected each other, being separated wide carbonate platforms, evolutionary trends. Stratigraphic studies place Triassic–Jurassic boundary 6–8 m thick intervals with anoxic basins. Relevant are also recorded Norian: sedimentation sulphate evaporites ended, replaced Rhaetavicula contorta facies; whilst (Lagonegro basin) deposition radiolarites began. end evaporite accumulation can be explained a climate change arid humid conditions, it probably linked extensional phase preceding rifting Ocean, may therefore have regional significance. Nevertheless, corresponds spread R. into other parts southern Europe, France Germany Austria. beginning radiolaritic could related rise atmospheric CO2 content, volcanic activity ridge. These reflect environmental caused decline some fossil associations favoring development opportunistic forms, e.g. Triasina hantkeni. end-Triassic extinction, coupled episode all examined basins, immediately preceded new change, documented recovery platforms oolitic associations. suggests geodynamics responsible events that, certain moments, reflected global effects as response connections between formerly Atlantic Magmatic Province (CAMP) volcanism, considered one possible causes mass would had even greater importance if volcanism Tethys.