CYCLOSTRATIGRAPHIC CALIBRATION OF THE LATE DEVONIAN AND IMPLICATION FOR BIO-CRISIS AND BIO-EVENT IN ILLINOIS BASIN, EASTERN UNITED STATES

The Late Devonian mass extinction of ~379 Ma to ~359 Ma is one of the big five Phanerozoic mass extinction events and is remarked by significant biodiversity losses. As it is characterized by recurrent bio-crises and bio-events of different orders (i.e., first-order to minor) over a long period, the Late Devonian is a proper geological window to track temporal interactive patterns between marine life and environment/climate. However, the poorly constrained timing and duration of the Late Devonian bio-crises and bio-events hinder revealing the dynamic relationship. Here, the Upper Devonian New Albany Shale, southern Illinois Basin, U.S., is used for the cyclostratigraphic, isotopic, trace-metal, and biomarker analyses. We detect the Milankovitch cycles via testing the Lomb-Scargle periodogram by the smoothed window-averaging, robust first-order autoregression, and false discovery rate. Thus, we construct the Early Frasnian-Middle Famennian time scale of ~378.9–~367.5 Ma via anchoring the F-F boundary at 371.1 Ma. δ¹³C combined with the time scale record the timing and duration for the first-order Upper Kellwasser bio-crisis (~371.5 Ma, ~1.11 Ma), the third-order Annulata bio-event (~368 Ma, ~191 kyr), the fourth-order punctata bio-event (~376 Ma, ~855 kyr), and the minor bio-events of the Rhinestreet (~374.5 Ma, ~672 kyr), semichatovae (~373 Ma, ~138 kyr), and Nehden (~370 Ma, ~236 kyr). The geological time scale, in correlation with profiles of oceanic oxygenation, eustatic level, and sea-surface temperature, is used to reveal the interaction of life and environment/climate. During the first-order Upper Kellwasser bio-crisis, the correlation suggests that long-period, benthic, dysoxic settings may be a niche for survivor species. During the third-order Annulata bio-event, euxinic intensification may cause biodiversity decline. Moreover, during the fourth-order punctata bio-event, the Siljan impact might trigger climate cooling and consequent biotic turnover. For the minor bio-events, rising eustatic levels may contribute to geographic radiation of deep marine species during the Rhinestreet. However, during the semichatovae and Nehden, oceanic oxygen depletion might stress biotic recovery. Intriguingly, volcanism likely causes global carbon cycle perturbation, climate warming, and marine anoxia during the Late Frasnian and Middle Famennian.