Decoding Late Maastrichtian Events: Volcanism, Ocean Changes, and the Chicxulub Impact in Central Anatolia, Turkey

The Göynük section emerges as a particularly valuable archive, preserving a continuous ~800 kyr stratigraphy from the CF4 to CF1 planktonic foraminiferal zones (~66.8–66.016 Ma), thus capturing the full trajectory of environmental perturbations leading to the KPg boundary. Notably, the progressive rise in planktonic δ¹³C values, peaks in Hg and Te concentrations between ~66.3–66.01 Ma and shifts in both planktonic and benthic δ¹⁸O point to intensified volcanic activity, most likely linked to the Poladpur pulse of the Deccan Traps. These signals—along with enhanced weathering, increased detrital input, and declining magnetic susceptibility—mark a phase of sustained environmental stress well before the Chicxulub impact. The correlation of benthic δ¹³C variability with Te enrichment suggests SO₂-induced ocean acidification and intermittent collapses/reductions of the export production as major ecosystem stress mechanisms during mid-CF2. In the Göynük and Okçular sections, the abrupt extinction of planktonic foraminifera, the sharp negative shift in δ¹³C_bulk, and the suite of impact proxies including trace element enrichments, such as an Ir anomaly at the KPg boundary in Göynük, reflect a robust signal of the Chicxulub event. The juxtaposition of both impact- and volcanism-related markers thus speaks for a compound scenario in which Deccan-driven perturbations fragilized marine ecosystems, while the Chicxulub impact delivered the final blow.