Astronomically calibrated integrated stratigraphy of the Induan Stage in the aftermath of the Permian–Triassic mass extinction

Accurately estimating the duration of the Induan Stage (Early Triassic) is crucial for understanding biotic recovery and environmental upheavals following the Permian–Triassic Mass Extinction. However, considerable uncertainties remain due to discrepancies between astrochronological and radiometric dating methods. In this study, we present an integrated stratigraphic framework for the Induan Stage by combining cyclostratigraphy, magnetostratigraphy, radiometric dating, biostratigraphy, and chemostratigraphy. By analyzing gamma ray series from marine deposits at the Xiejiacao, Chaohu, and Daxiakou sections in South China, and correlating them with biostratigraphic, magnetostratigraphic, geochemical, and radiometric data, we establish a composite 405-kyr eccentricity cycle-calibrated time scale. Our results estimate the Induan duration at 1.55 ± 0.2 Myr. Anchoring this time scale to the Permian–Triassic boundary at 251.902 ± 0.024 Ma, we propose an estimated age of 250.35 ± 0.2 Ma for the Induan–Olenekian boundary. By reconciling discrepancies between astrochronology and radiometric dating, our results provide a robust temporal framework for stratigraphic correlations, carbon cycle perturbations, and biotic and environmental changes in the aftermath of the mass extinction.