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
Shaohua Zhang, Wei-Qiang Ji, Houbin Chen, Linda A. Kirstein, Fu‐Yuan Wu
Abstract
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 km 3 /Ma, respectively. Evidence including the high average eruption flux (3994 km 3 /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 CO 2 that could drive the Early Eocene Climatic Optimum (EECO).