湖南省寒武系黑色岩系页岩型钒矿概论

湖南省寒武系黑色岩系蕴藏着丰富的钒矿资源,钒矿床产于寒武系底部富含有机质的碳、磷、硅质黑色岩系中;矿体呈层状、似层状,形态简单,产状稳定。多项测试结果表明,钒的载体岩石为黑色页岩(碳质页岩、硅质碳质页岩);钒主要呈类质同象形式赋存于伊利石晶格中;矿石类型主要为钒矿石,少数矿床中石煤钒矿石也是重要的矿石类型;钒的价态以V3+为主。钒的富集主要发生在沉积阶段,与黑色岩系的沉积过程一致;矿床形成于缺氧环境中,大部分钒被黏土质吸附,随有机质、黏土质和硅质呈胶态腐泥沉入海底;在成岩过程中,云母类黏土矿物结构发生再结晶,将原有表面吸附的钒(V3+)转化为类质同象形式进入云母晶格中取代部分铝(Al3+),形成含钒伊利石并聚集成为钒矿床。研究表明,本区黑色岩系及其有关的钒矿在沉积成岩成矿过程中都离不开生物地球化学作用,矿床成因属于在热水作用参与下沉积形成的海相化学和生物地球化学沉积矿床,矿床类型为黑色页岩型钒矿。

Overview on the Cambrian black shale-hosted vanadium deposit in Hunan

The Cambrian black shale is abundant with non-ferrous, precious, rare-earth metal and stone-coal, barite mineral resources in Hunan, especially for vanadium which is widely distributed with large resource potential and unique superior mineral resource of China. The vanadium deposit occurs at bottom of the black Cambrian organic material-rich, siliceous, carbonaceous and phosphorus shale. Ore bodies are stable in simple layer or layroid forms. Vanadium occurs as isomorph in illite crystal lattice. V-bearing black shale (carbonaceous shale, carbonaceous-siliceous shale) is the main vanadium ore type. However, in some vanadium deposits include stone-coal vanadium ore.V³⁺are dominant and vanadium is concentrated and syn-sedimented with the black shale under anaerobic condition. Most of the vanadium is absorbed by the clay minerals and precipitated at sea floor along with colloidal organic matter, clay minerals and siliceous materials. During diagenesis mica minerals were recrystalized into illite with involvement of the vanadium³⁺ substitution for A1³⁺ in the mineral lattices.The study shows that bio-geochemical process plays an important role during rock-forming of the black shale and ore-forming of the vanadium deposits. Genetically, the vanadium deposits are marine chemical and biageochemical sedimentary type and generally they are the black shale-hosted ore deposit.