碲的成矿作用及研究进展

General characteristics and research progress of tellurium mineralization

碲作为稀散元素,很少形成独立矿床,主要以共伴生形式产出于多个类型矿床中,包括铜镍硫化物和铂族矿床、铁氧化物铜金(IOCG)矿床、块状硫化物(VMS)矿床、斑岩矿床、矽卡岩矿床、造山型金矿、卡林型金矿和浅成低温热液矿床等。研究表明,碲元素可以形成上百种碲矿物,除了自然碲之外,多与Au、Ag、Pb、Bi、Cu等形成碲化物,与S或者Se形成碲的硫化物或硒化物,也可以形成碲酸盐、硅酸盐、磷酸盐、硫酸盐等矿物;此外Te还可以以类质同象形式替换寄主矿物中的元素。在成矿带尺度、矿床尺度及其矿石中碲均表现出极不均匀的分布特征,与主矿种Cu、Au、Ag等具有成因关系。碲具有多来源特征,可以源自地幔,也可以是浅部壳源岩浆或是围岩地层提供。碲矿化一般发生在成矿的中晚阶段,流体可通过混合作用、水岩反应、沸腾作用等改变体系的物理化学条件(如pH值、硫逸度、氧逸度、碲逸度、温度等),导致流体pH值升高、硫逸度和氧逸度降低,碲逸度升高,这是诱发碲矿物富集和沉淀的主要机制。碲由于其受控成矿条件较为特殊,需要着重加强碲富集成矿的关键控制因素、成矿物质来源和富集沉淀机制的研究。

Tellurium is an important critical metal.As a rare and scattered element,it rarely forms independent deposits,and mainly produced in many different types of mineral deposits.These deposits mainly including magmatic copper-nickel-platinum-group-metal sulfide deposits,iron oxide-copper-gold(IOCG)deposits,volcanogenic massive sulfide(VMS)deposits,porphyry deposits,skarn deposits,orogenic gold deposits,carlin-type gold deposits and epithermal deposits.Studies have shown that tellurium element can form hundreds of tellurium minerals.In addition to natural tellurium,most of them form telluride with Au,Ag,Pb,Bi,Cu,etc.,sulfide or selenide with S or Se,tellurite,silicate,phosphate,sulfate and other minerals,and tellurium can replace the elements of isomorphism in host minerals.Tellurium exhibits extremely uneven distribution characteristics at the scale of metallogenetic belt,deposits,and ores,and is genetically related to the main ore,such as Cu,Au,Ag,etc.The ore-forming material source of tellurium can be provided by regional mantle plume activity and magma degassing products,shallow crust magma or wall rocks.In most ore deposits,telluride mineralization consistently is deposited in the later stages of paragenetic sequences.The main mechanism of tellurium mineral enrichment and deposition are fluid mixing,water rock reaction and boiling can change the physical and chemical conditions of the system(such as pH value,sulfur fugacity,oxygen fugacity,tellurium fugacity,temperature,etc.),which leads to the increase of pH value,reduction of sulfur and oxygen fugacity of the fluid,and the increase of tellurium fugacity.Due to the special controlled ore-forming conditions,it is necessary to strengthen the research on the key controlling factors,ore-forming material sources,enrichment and precipitation mechanism of tellurium deposit.