Linking rapid eruption of the Linzizong volcanic rocks and Early Eocene Climatic Optimum (EECO): Constraints from the Pana Formation in the Linzhou and Pangduo basins, southern Tibet

Volcanic eruptions can release a large amount of volatiles, including sulfur dioxide and carbon dioxide, into the atmosphere and trigger regional and/or global perturbations of the climate and environment. However, the potential effect of the Linzizong volcanism, the most intense and widespread magmatism in southern Tibet, is not yet known. Here, the systematic results of fieldwork, spatial distribution analysis (area and volume), and zircon U-Pb age dating of 54 samples are reported from the Linzizong volcanic rocks (Dianzhong, Nianbo and Pana Formations) in the Linzhou and Pangduo basins, southern Tibet. Our new zircon U-Pb ages of 40 samples and compilations of previous data indicated that the Pana Formation erupted rapidly ca. 52-50 Ma, consistent with the coeval "flare-up" (-51 Ma) of the Gangdese batholith. The average eruption fluxes of the lower (Dianzhong Formation), middle (Nianbo Formation), and upper (Pana Formation) parts of the Linzizong volcanic sequence are 11.8, 1.44, and 3994 km3/Ma, respectively. Evidence including the high average eruption flux (3994 km3/ Ma), large magnitude (M = 8.80), and Volcanic Explosivity Index (VEI = 8) of the Pana Formation in the Linzhou and Pangduo basins suggests that this may represent a "supereruption" event in the Early Eocene. The rapid eruption of the Pana Formation was pervasive across the Tibetan Plateau and potentially extends to Sumatra, Southeast Asia, with consequences for the release of a large amount of CO2 that could drive the Early Eocene Climatic Optimum (EECO).