Side by side with a volcano: a Early Permian deltaic to lacustrine basin under the effect of volcanic activity

Sinich/Sinigo, situated within the Athesian Volcanic District in Northern Italy, yielded an exceptional plant fossil assemblage from the middle Kungurian (Cisuralian), including permineralized stems, compressions, and molds of such diverse plant groups as lycopsids, sphenophytes, ferns, seed ferns, cordaitaleans, and conifers. Notably, the site features the earliest record of coexistence of walchian and voltzian Voltziales conifers, whose exceptional three-dimensional preservation provides evidence of xeromorphic adaptations such as fleshy and deciduous leaves. Additionally, the basin contains the oldest in situ fossil forest in Italy, which was preserved in its original growth position on a deltaic sheetflood fan and subsequently buried by mass flows, illustrating the conifers' significant ecomorphological adaptability in response to waterlogged conditions. Palynological analyses reveal a predominance of woody tissue and charcoal in the lower and middle part of the succession with an increase of spores and pollen in the upper part of the succession. Geochemical analyses on trace elements are rather monotonous in the lower part of the successions but show notable fluctuations in the upper part with pronounced peaks in the abundance of S, As, Pb. Indices of chemical alteration (CIA, PIA, CIW) support significant environmental changes in the later stages of the evolution of the basin, while the isotopic composition of bulk organic carbon remained stable. These analyses underscore Sinich/Sinigo as a key site for understanding the ecological and environmental dynamics of the middle Kungurian, offering valuable insights into the interactions between volcanic activity, weathering and biotic responses.