| 6241铀矿床围岩蚀变、矿化特征及成因初步认识 |
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| 引用本文：.1984.A Preliminary Understanding Of The 6241 0re Deposit-Its Wall Rock Alteration And Uranium Mineralization[J].Mineral Deposits,3(2):85~93 |
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| Author Name | Affiliation | | 陈松茂 | |
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| A Preliminary Understanding Of The 6241 0re Deposit-Its Wall Rock Alteration And Uranium Mineralization |
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| Abstract:Located on the western flank of the Wuyishan structural zone and also at the western margin of a block basin, the uranium deposit in question is unexceptionally controlled by structural features. Uranium ore occurs chiefly in Cretaceous granitic conglomeratic sandstone and, to a less extent, in coarse-grained porphyritic biotite granite, with basically identical mineralization characteristics in both rocks. Mineralization could be predominantly classified into uranium-chalcedony type and uranium-hydromica type. A fairly distinct alteration zoning has been recorded on either side of the uranium-chalcedony type deposit. From the ore body outward, alteration changes from heavy silicification, hematitization and pyritization to hydromicatization, accompanied by a decrease of SiO2, Fe2O3 and FeO and an increase of Al2O3 and Na2O. Uranium occurs mainly as pitchblende and secondarily as adsorbed material in ore. Pitchblende often surrounds and replaces pyrite as veinlets or impregnations and possesses colloform texture. This mineral contains comparatively high SiO2, Al2O3 and MgO and relatively low Pb, suggesting rapid crystallization and young formation age-its age is dated isotopically at 42 m.y. Occurring mainly in granitic conglomeratic sandstone, the uranium-hydromica type mineralization is characterized by intense hydromicatization and desilication accompanied by montmorillonitization and pyritization, commonly known as decolorization alteration. In addition to particles of secondary uranium minerals, uranium has been absorbed as scattered material by oxidized pyrite, limonite and hydromica, and no pitchblende has yet been found in the ore. Uranium has a close relationship with water with a correlation coefficient of 0.58 (n=24, γ0.05=0.404). It also has a rather high electrodialysis coefficient (52.74—75.30%). All this distinguishes it from the uranium-chalcedony type. This uranium deposit is of low-temperature hydrothermal origin; silicification had a most important bearing on uranium mineralization; pyrite played a substantial role in uranium concentration; supergene superimposifaon could be observed in some places; uranium was derived mostly from the surrounding granite. |
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