LARGE PERTURBATIONS OF THE GLOBAL CARBON CYCLE AND DELAYED RECOVERY FROM THE END-PERMIAN EXTINCTION

We sampled the Great Bank of Guizhou (GBG), an isolated Late Permian to Late Triassic carbonate platform in the Nanpanjiang Basin of Guizhou Province, southern China, to obtain high-resolution carbon isotopic profiles and fossil occurrence data from the Late Permian through the Middle Triassic Period. The exposure of sections in both platform interior and basin margin settings further allows us to compare data across a range of depositional environments. Our results demonstrate that the carbon isotopic excursion at the Permian-Triassic boundary was the first in a series of (mostly larger) excursions that continued into the early part of the Middle Triassic, consistent with more limited data from previous studies. The excursions ended rapidly in the early Anisian (Bithynian), and were followed by an extended interval of stable values near 2‰ through the remainder of the Middle Triassic and into the Carnian. Fossil occurrence data show that low diversity, mollusk-dominated ecosystems persisted relatively unchanged on the GBG throughout the Early Triassic. Increase in the abundance and diversity of fossils began in the Spathian and accelerated in the Anisian, primarily along the platform margin and within the platform-margin reef complex. Skeletal material from the platform margin community is dominated by crinoids and the problematicum Tubiphytes. Local recovery on the GBG appears contemporaneous with recovery globally using several independent metrics. Global diversity increased substantially during the Anisian, while large gastropods, calcareous algae and calcareous sponges returned to the rock record following Early Triassic absences. The Early Triassic interval of carbon cycle instability coincides in time with the delayed recovery from end-Permian extinction recorded by fossils both locally and globally, suggesting a direct relationship between Earth system function and biological rediversification in the aftermath of Earth’s most devastating mass extinction.