Integrated palynological and ammonoid data from the uppermost Jurassic (Tithonian) deposits of Brzostówka, Poland, and its biostratigraphical and paleoenvironmental implications

During the Late Jurassic, Earth experienced significant environmental changes impacting both marine and terrestrial ecosystems. This study combines new palynological and ammonite associations from the Brzostówka section, central Poland. The work aims to improve the stratigraphical resolution using ammonoid-based dating and interpret the paleoenvironment and paleoecology of the marine and terrestrial communities during the latest Jurassic. Ammonites Blaschkeiceras sp. and Ernstbrunnia sp. are identified underlying the newly reported palynological association belonging to the Standard Tethyan Fallauxi Zone. Both marine (more abundant) and terrestrial palynomorphs are reported. A total of 42 morphotypes were identified, and key taxa such as Cicatricosisporites sp., Wrevittia diutina, Pilosidinium myriatrichum, Dingodinium jurassicum, and Dingodinium minutum were used for age assignment corresponding to the upper part of the lower Tithonian, consistent with ammonite biozonation. The presence of ammonites and the dominance of marine palynomorphs indicates a marine or paralic depositional environment, likely within the neritic zone. The marine fraction of the palynological association is dominated by Gonyaulacales and indicates an environment with low nutrient availability. The plant communities, likely located in coastal areas close to the depositional site, were dominated by Cheirolepidiaceae conifers suggesting warm conditions. Additionally, the presence of other gymnosperm pollen and diverse spores of pteridophytes and bryophytes unveil the presence of a variety of plant families living in the area, with several ferns and mosses families inhabiting humid environments near freshwater sources.