Association of Seismites and Poly Aromatic Hydrocarbons (PAHs) as Evidence for Boundaries between Geological Periods delimited by Extinction Events

The definition of geological period boundaries has historically relied on bio-, chemo-, and magnetostratigraphic markers. However, a unified physical-geochemical trigger for the global synchrony of these boundary crises remains unresolved. This study proposes a quantitative, structural-geochemical "ruler" to define boundary layers throughout the Phanerozoic and Precambrian. We demonstrate that boundary events are marked by a systematic coupling within the same geological layer, but not necessarily at the same location, between metric-thick seismites reflecting soft-sediment deformation structures (SSDS) induced by peak ground acceleration (), and sharp anomalies in alkylated polycyclic aromatic hydrocarbons (PAHs), driven by seismic cap-rock failure and hydrocarbon paleo-leakage from depressurized deep reservoirs. To formalize this mechanism, we postulate that the synchronous co-occurrence of global seismites and petrogenic PAH spikes serves as diagnostic evidence of global extinction events, whereas localized occurrences reflect regional biomial stress. Extended to the Precambrian, where petroleum generation traces back near LUCA, this framework provides an innovative, non-fossil-dependent GSSP (Global Boundary Stratotype Section and Point) calibration tool, offering unprecedented insights into planetary habitability, early biological bottlenecks, and ancestral cellular evolution mechanisms.