A short-term warming interval during the apex of the Late Paleozoic Ice Age: Evidence from geochemical and magnetic records from South China

Abstract

The Late Paleozoic Ice Age (LPIA) was the longest-lasting icehouse in the Phanerozoic. Previous studies indicated a climate warming interval in the earliest Permian—an apex of the LPIA. To better understand hydroclimatic changes and carbon cycling within this time interval, we conducted a series of high-resolution geochemical and rock magnetic analyses, including magnetic measurements (e.g., magnetic susceptibility, anhysteretic remanent magnetization, hysteresis loops, temperature-dependent susceptibility), ratio of iron to potassium (Fe/K), and carbonate carbon isotope (δ13Ccarb) from a deep-marine section in South China. Calibrated to the published astronomical time scale, a negative δ13Ccarb excursion (−1‰) was identified during 298.4–297.9 Ma, and it was time-equivalent with the warming interval, recognized by a decrease in conodont apatite oxygen isotopes in South China, low-latitude sea-level transgression, and high-latitude deglaciation. The negative δ13Ccarb excursion also coincided with a magmatic pulse of the Skagerrak-Centered Large Igneous Province (LIP), indicating that the perturbation in carbon cycling is likely associated with the release of volcanic CO2. Furthermore, cyclostratigraphic analysis on multiple paleoclimatic proxies, including ferrimagnetic susceptibility, gamma-ray, and Fe/K, suggested that the negative excursion of δ13Ccarb also overlapped with the maximum of the eccentricity cycle. It implied that orbital configurations may amplify the feedback of the LIP, causing this short-term warming interval.