Abnormal pollen grains: an outcome of deteriorating atmospheric conditions around the Permian - Triassic boundary

Records of abnormal gymmosperm pollen morphotypes from coeval localities in Russia and NW China provide independent and unique evidence of deteriorating atmospheric conditions at the close of the Permian. Although at similar palaeolatitude, the Vologda region of European Russia and the Junggar Basin of Xinjiang Province, China, were thousands of kilometres apart and on different tectonic plates. The co-occurrence of the megaspore Otlynisporites eotriassicus Fuglewicz 1977, and its restricted distribution elsewhere in marine sections with either Late Permian ammonoids or the basal Triassic conodont marker Hindeodus parvus, confirms the age range, and correlation of the Russian and NW Chinese sections. In three Chinese sections, rapid changes in carbon isotopic (delta C-13(org)) composition of between 4 and 10 parts per thousand occur over the intervals showing abnormal pollen. These patterns reflect bioclastic facies contributions responding to local environmental changes. They are nevertheless coincident with global perturbations in the atmosphere, caused by extensive volcanic activity around the Permian-Triassic boundary.