Evolution of arsenic and selenium of coals during mass extinction of land species in the Permian in southwestern China and its palaeoenvironmental significance
Luo Kunli Li Huijie Niu Caixiang Chen Tongbin
Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101
To investigate the arsenic(As)and selenium(Se)content and evolution in different coal components of the coal measures of the Longtan Formation as well as its palaeoenvironmental significance during the early and middle periods of Late Permian(Lopingian)in southwestern China，the As and Se content were detected and analyzed in the samples of raw coal，clarain，coal gangue and pyritic nodule which were collected from the main coal seams in southwestern China during the last 10 years，and the results were compared with that of the Taiyuan Formation and Shanxi Formation of Late Carboniferous and Early Permian in the North China Plate. The results show that the As and Se content of the coal measures of Longtan Formation in the Late Permian in southwestern China changed greatly and the As and Se content is higher than that of the Late Carboniferous and Early Permian coals in the North China Plate；the As and Se content of the Late Permian clarain coals in southwestern China is higher than that of the channel sampling coals or raw coal and coal gangue，especially the As content of the Late Permian clarain(from 55 to 338 mg/kg，some reaches 89 mg/kg)is much higher in southwestern China. The As and Se content in the coals of Taiyuan Formation and Shanxi Formation of the Late Carboniferous and Early Permian in the North China Plate is contrary to southwestern China，that is, the As and Se content of the Late Carboniferous and Early Permian vitrain and clarain is very low. The As content ranges from 063 to 129 mg/kg，lower than that of the channel sampling coals or raw coal and the gangue in the North China Plate. The analysis indicates that the source of As and Se in the Late Permian coals in southwestern China is closely related with the organic component of coals，and the As and Se in coals is mainly derived from the coalforming paleoplants in southwestern China. The results also show that during the mass extinction of land species in the Late Permian，the land species food，namely, the plants had an increasing content of As and Se，and the content of the soluble As and Se in land environment or the peat
swamp also increased.
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Evolution of arsenic and selenium of coals during mass extinction of land species in the Permian in southwestern China and its palaeoenvironmental significance[J]. JOPC, 2008, 10(4): 385-394.
