Sedimentary evolution of the Mesozoic continental redbeds using geochemical and mineralogical tools: the case of Upper Triassic to Lowermost Jurassic Monte di Gioiosa mudstones (Sicily, southern Italy)

The continental redbeds from the Internal Domains of the central-western Mediterranean Chains have an important role in the palaeogeographic and palaeotectonic reconstructions of the Alpine circum-Mediterranean orogen evolution since these redbeds mark the Triassic- Jurassic rift-valley stage of Tethyan rifting. The composition and the sedimentary evolution of the Middle Triassic to Lowermost Jurassic continental redbeds of the San Marco d’Alunzio Unit (Peloritani Mountains, Southern Italy), based on mineralogical and chemical analyses, suggests that the studied mudrock sediments share common features with continental redbeds that constitute the Internal Domains of the Alpine Mediterranean Chains. Phyllosilicates are the main components in the mudrocks. The 10 A ° -minerals (illite and micas), the I–S mixed layers, and kaolinite are the most abundant phyllosilicates. The amount of illitic layers in I–S mixed layers coupled with the illite crystallinity values (IC) are typical of high degree of diagenesis, corresponding to a lithostatic/tectonic loading of about 4–5 km. The mineralogical assemblage coupled with the A-CN-K plot suggest post-depositional K-enrichments. Palaeoweathering proxies (PIA and CIW) record intense weathering at the source area. Further, the studied sediments are affected by reworking and recycling processes and, as consequence, it is likely these proxies monitor cumulative effect of weathering. The climate in the early Jurassic favoured recycling and weathering occurred under hot, episodically humid climate with a prolonged dry season. The source-area is the low-grade Paleozoic metasedimentary basement. Mafic supply is minor but not negligible as suggested by provenance proxies.