| 华东一多金属铀矿床的地质特征及成矿条件的初步探讨 |
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| 引用本文：.1985.A preliminary study on geological features and metallogenic conditions of a polymetallicuranium deposit in east China[J].Mineral Deposits,4(3):31~39 |
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| A preliminary study on geological features and metallogenic conditions of a polymetallicuranium deposit in east China |
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| Abstract:The ore deposit in question is situated at the southwestern margin of a Mesozoic volcanic basin on the coastal fracture and volcanic zone of China, with the basement of the volcanic basin composed of pre-Devonian metamorphic sequence of Chenai Group (AnDch) and the overlying strata made up of Lower Jurassic fluviatile-lacustrine facies sediments of Fengping Formation and Upper Jurassic volcano-sedimentary sequence of intermontane basin. The ore deposit occurs in a volcano-tectonic depression, with the Upper Jurassic 1st -4th sectors exposed at the surface and the serving as the major mineralized bed. There are two volcanic vents lying in t he east of the volcano-tectonic depression, and several ring-shaped faults are seen distributed around the eastern vent, dipping towards the root of this vent. Orebodies mostly occur within the ring-shaped faulted zone, both having identical strike and dip. The ore belongs industrially to comprehensive uranium molybdenum-silver type and the useful elements are present mainly in the form of independent minerals. The main metallic minerals in ore are pitch blende, uraniferous jordisite, molybdenite, argentite, acanthite, pyrite, melnikovi-tepyrite, sphalerite, galena, etc. and the major vein minerals include chalcedony, fluorite, quartz, feldspar, sericite, hydromica, etc.The ore assumes metasomatic, metasomatic relict, colloform, inclusive and porphyritic textures as well as breeciated, disseminated, mesh and veinlike structures. The U content is in direct proportion to Mo and Ag contents. The main wall rock alterations observed in the ore deposit are silicification, pyritizaton, fluoritization, potassium alteration, sericitization, hydromicatization, etc．Mineralization is associated intimately with black chalcedony, melnikovite-pyrite and powder-pyrite, violet-black fluorite. The ore deposit has possessed several geological conditions favorable for mineralization: 1)The regional tectonic movement and magmatic activities provided good prerequisites for ore formation ;2) iolcano-tectonic depression played the function of artesian action for the migration of ore solutiom; 3) the volcanic vent and the ring-shaped faults around it offered favorable chart nelways for the migration of ore solutions and space for mineralizaton; 4)the sphero-blister rhyolite furnished the most favorable wall rock conditions for mineralization; 5)the volcanoclastic rocks overlying the sphero-blister rhyolife acted as a fine shield bed; 6) the ore deposit underwent repeated intense hydrothermal activities which facilitated mineralization. The preliminary study of the metallogenic conditions of the ore deposit, combined with an integrated analysis of such factors as geological setting, orebody distribution features, mineral association, ore texture and structure, occurrence mode of useful elements, wall rock alteration has led the author to believe that the polymetallie uranium deposit under discussion is genetically of post-volcanism mesothermal-epithermal filling-metasomatic type. |
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