Ziyang County, Shaanxi Province, China is a world known selenium（Se）-enriched area, and a severe selenosis incident was reported in Naore Village during the 1990 s. This study investigated the geochemical characteri...Ziyang County, Shaanxi Province, China is a world known selenium（Se）-enriched area, and a severe selenosis incident was reported in Naore Village during the 1990 s. This study investigated the geochemical characteristics of Se and its fractions in Se-enriched rocks from Ziyang. Se distribution is uneven, ranging from 0.23 to 57.00 μg/g（17.29±15.52 μg/g）. Se content is higher in slate than chert, and even lower in carbonate rocks. Cd, As and V are enriched but Pb is depleted in Se-enriched strata. Se has different correlations both with TS（total sulfur）（R^2=0.59 for chert） and TC（total carbon）（R^2=0.77 for slate, R^2=0.87 for carbonate）. Se has significant positive correlations with V（r=0.65）, As（r=0.485）, Cd（r=0.459） and Pb（r=0.405）. The Se level correlates with mineral content, positively with pyrite, chlorite and illite, negatively with albite. Se associated with sulfide/selenide and elemental Se are the predominant fractions of total recovered Se, suggesting that a reducing environment and the formation of sulfides were significant to Se deposition during its geochemical cycle. Although low concentration of bio-available Se（average 5.62%±3.69%） may reduce the risk of Se poisoning in the target area, utilization of Se-rich rock as natural fertilizer should be restricted.展开更多
Bamnet Narong is located in northeastern Thailand (Chaiyaphum Province). It is the largest salt mine in the country and has been mined for decades. The landscape in this part of Thailand is characterised by a low plat...Bamnet Narong is located in northeastern Thailand (Chaiyaphum Province). It is the largest salt mine in the country and has been mined for decades. The landscape in this part of Thailand is characterised by a low plateau, which is called the Khorat Plateau. The plateau is divided into two basins by the Phu Phan Range, the Sakhon Nakhon Basin in the north and the Khorat Basin in the south. The analysed potashes and rock salts are deposited in the Maha Sarakham Formation, which represents the salt-bearing strata of the Khorat Basin. The stratigraphic age of this deposit has been debated since the late 1960’s. The assigned ages range from Mid-Cretaceous to Late Cretaceous and up to the Eocene. In this study different isotopic dating systems (Rb-Sr, Sr-Sr, K-Ar and K-Ca) were applied. The stratigraphic age for the time of deposition was confirmed to be Mid Cretaceous (Cenomanian). Furthermore, the homogeneity of the carnallites was investigated in order to trace a possible redistribution of rubidium.展开更多
基金supported by the Foundation of China Geological Survey(Nos.12120113087100,12120113022600)the Basic Scientific Research of the Institute of Geophysical Geochemical Exploration,Chinese Academy of Geological Sciences(No.WHS201302)
文摘Ziyang County, Shaanxi Province, China is a world known selenium（Se）-enriched area, and a severe selenosis incident was reported in Naore Village during the 1990 s. This study investigated the geochemical characteristics of Se and its fractions in Se-enriched rocks from Ziyang. Se distribution is uneven, ranging from 0.23 to 57.00 μg/g（17.29±15.52 μg/g）. Se content is higher in slate than chert, and even lower in carbonate rocks. Cd, As and V are enriched but Pb is depleted in Se-enriched strata. Se has different correlations both with TS（total sulfur）（R^2=0.59 for chert） and TC（total carbon）（R^2=0.77 for slate, R^2=0.87 for carbonate）. Se has significant positive correlations with V（r=0.65）, As（r=0.485）, Cd（r=0.459） and Pb（r=0.405）. The Se level correlates with mineral content, positively with pyrite, chlorite and illite, negatively with albite. Se associated with sulfide/selenide and elemental Se are the predominant fractions of total recovered Se, suggesting that a reducing environment and the formation of sulfides were significant to Se deposition during its geochemical cycle. Although low concentration of bio-available Se（average 5.62%±3.69%） may reduce the risk of Se poisoning in the target area, utilization of Se-rich rock as natural fertilizer should be restricted.
文摘Bamnet Narong is located in northeastern Thailand (Chaiyaphum Province). It is the largest salt mine in the country and has been mined for decades. The landscape in this part of Thailand is characterised by a low plateau, which is called the Khorat Plateau. The plateau is divided into two basins by the Phu Phan Range, the Sakhon Nakhon Basin in the north and the Khorat Basin in the south. The analysed potashes and rock salts are deposited in the Maha Sarakham Formation, which represents the salt-bearing strata of the Khorat Basin. The stratigraphic age of this deposit has been debated since the late 1960’s. The assigned ages range from Mid-Cretaceous to Late Cretaceous and up to the Eocene. In this study different isotopic dating systems (Rb-Sr, Sr-Sr, K-Ar and K-Ca) were applied. The stratigraphic age for the time of deposition was confirmed to be Mid Cretaceous (Cenomanian). Furthermore, the homogeneity of the carnallites was investigated in order to trace a possible redistribution of rubidium.
