This paper deals with thallium in typical low-temperature deopits of Au, Tl, As,Sb and Hg in South China with respect to its mode of occurrence, minerals and geochemicalcorrelations with many other coexisting major an...This paper deals with thallium in typical low-temperature deopits of Au, Tl, As,Sb and Hg in South China with respect to its mode of occurrence, minerals and geochemicalcorrelations with many other coexisting major and trace elements. Criteria are proposed for i-dentifying independent thallium deposits and thallium-bearing deposits and the Nanhua realgardeposit is classified for the first time as an independent thallium deposit. Tl, F, Cl, I and B aresuggested as indicators for low-temperature mineralization with examples furnished for their ap-plications.展开更多
The stream sediments of Wadi El Reddah(North Eastern Desert,Egypt)are geochemically and mineralogically investigated.Their content of radioactive and other heavy minerals is mainly represented by thorite,uranothorite,...The stream sediments of Wadi El Reddah(North Eastern Desert,Egypt)are geochemically and mineralogically investigated.Their content of radioactive and other heavy minerals is mainly represented by thorite,uranothorite,zircon,monazite,xenotime,columbite,fergusonite,and unknown rare earth elements(REEs)bearing minerals as well as cassiterite.Special emphasis on REE content of thorite,uranothorite,zircon and xenotime has been done to correlate them with the increase of uranium contents in these sediments.The key evidence for the presence lowtemperature alteration processes includes the presence of some zircon crystals as remnants after complete dissolution of the overgrowth zircon in severe acidic environment,the sulphur content,biogenic minerals,occurrence of unusual minerals as cassiterite pore filling in zircon,variation in the REEs content from the surrounding granites to the stream sediments and the abundance of monazite in the surrounding granites.Most minerals are partially and/or completely altered,which indicated by the pseudomorphism of zircon by xenotime,thorite,and uranothorite.展开更多
We have reported that the roots of figleaf gourd(Cucurbita ficifolia,as rootstock) could improve the resistance of cucum-ber seedlings(Cucumis sativus L.cv.Jinyan 4,as scion) to 6 h stress at low temperature and low i...We have reported that the roots of figleaf gourd(Cucurbita ficifolia,as rootstock) could improve the resistance of cucum-ber seedlings(Cucumis sativus L.cv.Jinyan 4,as scion) to 6 h stress at low temperature and low irradiance [1].In this experiment,the relationship between the mineral elements uptake and photosynthetic activity of photosystems in figleaf gourd and cucumber seedlings were to be studied during lowtemperature(8 C) stress under lowirradiance(100 μmol m-2 s-1 PFD) for 5 days.Compared with control seedlings,the maximal photochemical efficiency of PS2(Fv/Fm) and the oxidizable P700(P700+) of both figleaf gourd and cucumber seedlings decreased,and both Fv/Fm and P700+ were lower in cucumber leaves than in figleaf gourd seedlings at the end of the stress.Superoxide dismutase(SOD) activity was higher in both leaves and roots of figleaf gourd than in leaves and roots of cucumber at both room temperature and low temperature.However,the product rate of O 2 was lower in figleaf gourd leaves than in cucumber leaves.Upon ex-posure to the stress,the malondialdehyde(MDA) content increased markedly in leaves and roots of figleaf gourd and cucumber seedlings,and it grewfaster in cucumber seedlings than that in figleaf gourd seedlings.Under adaptive conditions,some mineral elements(Such as Cu,Zn,Mn and Mg) have different contents in leaves and roots between figleaf gourd seedlings and cucumber seedlings.However,at the end of the stress these elements were accumulated apparently in both leaves and roots of figleaf gourd accompanied by no obvious change in cucumber seedlings.展开更多
THE term epithermal as a kind of hydrothermal mineralization was first used by Lindgren in 1933. It describes those ore-forming systems occurring at depths mainly less than 1 km, and at temperatures less than300℃. Ep...THE term epithermal as a kind of hydrothermal mineralization was first used by Lindgren in 1933. It describes those ore-forming systems occurring at depths mainly less than 1 km, and at temperatures less than300℃. Epithermal deposits of Cenozoic ages are widely distributed in the Circum-Pacific belt, especiallyin the Southwest Pacific area. From the 1980s on, the study of epithermal ore deposits became an important field of mineral deposit research. Hayba et al.and Hedenquist classified the epithermal systemas adularia-sericite or acid-sulphate types, and low sulphidation or high sulphidation types, respectively.The low temperature mineralization, which was exemplified by the deposits in southwest China, refers tothe system at temperature mainly less than 200℃. Besides the distinction in temperature, however, thereexist many differences between epithermal and low temperature mineralizations.展开更多
THE parallel strike of geochemical steep zones and geophysical gradient zones represent geochemicalboundaries with tectonic hiding and almost no magmatism, but there existed great variation of lithosphereor crustal th...THE parallel strike of geochemical steep zones and geophysical gradient zones represent geochemicalboundaries with tectonic hiding and almost no magmatism, but there existed great variation of lithosphereor crustal thickness. Tectonically, these areas were located in the foreland basins of craton margin. Thesegeochemical boundaries were usually associated with the low-temperature mineralization and petroleumgeneration. The Nd, Sr and Pb isotopic evidence indicated that there still existed strong crustal-mantle interaction through fluid activation along deep-seated faults at the craton margin. Fig. 1 is the <sup>207</sup>Pb/<sup>204</sup> Pb-<sup>208</sup>Pb/<sup>204</sup> Pb diagram, which shows the evident crust-mantle mixing for crude oil, chloroform bitumen-A,展开更多
文摘This paper deals with thallium in typical low-temperature deopits of Au, Tl, As,Sb and Hg in South China with respect to its mode of occurrence, minerals and geochemicalcorrelations with many other coexisting major and trace elements. Criteria are proposed for i-dentifying independent thallium deposits and thallium-bearing deposits and the Nanhua realgardeposit is classified for the first time as an independent thallium deposit. Tl, F, Cl, I and B aresuggested as indicators for low-temperature mineralization with examples furnished for their ap-plications.
文摘The stream sediments of Wadi El Reddah(North Eastern Desert,Egypt)are geochemically and mineralogically investigated.Their content of radioactive and other heavy minerals is mainly represented by thorite,uranothorite,zircon,monazite,xenotime,columbite,fergusonite,and unknown rare earth elements(REEs)bearing minerals as well as cassiterite.Special emphasis on REE content of thorite,uranothorite,zircon and xenotime has been done to correlate them with the increase of uranium contents in these sediments.The key evidence for the presence lowtemperature alteration processes includes the presence of some zircon crystals as remnants after complete dissolution of the overgrowth zircon in severe acidic environment,the sulphur content,biogenic minerals,occurrence of unusual minerals as cassiterite pore filling in zircon,variation in the REEs content from the surrounding granites to the stream sediments and the abundance of monazite in the surrounding granites.Most minerals are partially and/or completely altered,which indicated by the pseudomorphism of zircon by xenotime,thorite,and uranothorite.
基金This research was supported by the Natural Science Foun-dation of China(30571126,30671242)the Scientific Research Encouragement Foundation for Outstanding Young and Middleaged Scientists of Shandong Province,China(2005BS06003)
文摘We have reported that the roots of figleaf gourd(Cucurbita ficifolia,as rootstock) could improve the resistance of cucum-ber seedlings(Cucumis sativus L.cv.Jinyan 4,as scion) to 6 h stress at low temperature and low irradiance [1].In this experiment,the relationship between the mineral elements uptake and photosynthetic activity of photosystems in figleaf gourd and cucumber seedlings were to be studied during lowtemperature(8 C) stress under lowirradiance(100 μmol m-2 s-1 PFD) for 5 days.Compared with control seedlings,the maximal photochemical efficiency of PS2(Fv/Fm) and the oxidizable P700(P700+) of both figleaf gourd and cucumber seedlings decreased,and both Fv/Fm and P700+ were lower in cucumber leaves than in figleaf gourd seedlings at the end of the stress.Superoxide dismutase(SOD) activity was higher in both leaves and roots of figleaf gourd than in leaves and roots of cucumber at both room temperature and low temperature.However,the product rate of O 2 was lower in figleaf gourd leaves than in cucumber leaves.Upon ex-posure to the stress,the malondialdehyde(MDA) content increased markedly in leaves and roots of figleaf gourd and cucumber seedlings,and it grewfaster in cucumber seedlings than that in figleaf gourd seedlings.Under adaptive conditions,some mineral elements(Such as Cu,Zn,Mn and Mg) have different contents in leaves and roots between figleaf gourd seedlings and cucumber seedlings.However,at the end of the stress these elements were accumulated apparently in both leaves and roots of figleaf gourd accompanied by no obvious change in cucumber seedlings.
文摘THE term epithermal as a kind of hydrothermal mineralization was first used by Lindgren in 1933. It describes those ore-forming systems occurring at depths mainly less than 1 km, and at temperatures less than300℃. Epithermal deposits of Cenozoic ages are widely distributed in the Circum-Pacific belt, especiallyin the Southwest Pacific area. From the 1980s on, the study of epithermal ore deposits became an important field of mineral deposit research. Hayba et al.and Hedenquist classified the epithermal systemas adularia-sericite or acid-sulphate types, and low sulphidation or high sulphidation types, respectively.The low temperature mineralization, which was exemplified by the deposits in southwest China, refers tothe system at temperature mainly less than 200℃. Besides the distinction in temperature, however, thereexist many differences between epithermal and low temperature mineralizations.
文摘THE parallel strike of geochemical steep zones and geophysical gradient zones represent geochemicalboundaries with tectonic hiding and almost no magmatism, but there existed great variation of lithosphereor crustal thickness. Tectonically, these areas were located in the foreland basins of craton margin. Thesegeochemical boundaries were usually associated with the low-temperature mineralization and petroleumgeneration. The Nd, Sr and Pb isotopic evidence indicated that there still existed strong crustal-mantle interaction through fluid activation along deep-seated faults at the craton margin. Fig. 1 is the <sup>207</sup>Pb/<sup>204</sup> Pb-<sup>208</sup>Pb/<sup>204</sup> Pb diagram, which shows the evident crust-mantle mixing for crude oil, chloroform bitumen-A,
