Deccan volcanic eruptions and their impact on flora; palynological evidence

Palynological studies of the late Maastrichtian infratrappean and intertrappean sedimentary beds from various stratigraphic levels in the Deccan continental flood basalt of the Nand-Dongargaon Basin in central India show that infratrappean sediments (Maastrichtian C30n-C29r) are characterized by gymnosperm (Araucariacites, Classopollis, Cycadopites, Podocarpidites) and angiosperm (Cretacaeiporites, Compositoipollenites, Graminidites, Longapertites, Palmaepollenites) palynomorphs. A distinct floral turnover is observed in intertrappean sediments with the initiation of volcanic activity in the basin. At the lowest stratigraphic level, the earliest floral change is recorded by the appearance of angiosperm-pteridophyte-dominated association (Aquilapollenites, Azolla, Gabonisporis, Tricolpites, Triporopollenites, and Normapolles group pollen) and the appearance of peridinoid dinoflagellates. At higher stratigraphic levels in C29r, this palynofloral association continues with the appearance of new forms, such as Scabrastephanocolpites spp., Scollardia conferta, and Triporopollenites cracentis. A sharp decline in diversity of titanosauriform-abelisaurid-dominated dinosaurian fauna is also observed with the onset of Deccan volcanic activity. At this time, out of at least eight dinosaur species, only a single taxon of titanosauriform dinosaurs survived the onset of volcanism. This suggests that the floral change and decreased dinosaur diversity are strongly linked with the initiation of Deccan volcanism in C29r in India. The peak eruption of this volcanic phase resulted in the Deccan's largest volume of lava flows, which played a significant role in the global mass extinction at the Cretaceous-Paleogene boundary.