内蒙古大井锡多金属矿床锡矿物特征  

CHARACTERISTICS OF TIN MINERALS FROM DAJING TIN-POLYMETALLIC DEPOSIT,INNER MONGOLIA,CHINA

作　　者：王玉往[1] 王京彬[2] 王莉娟[2] 

机构地区：[1]中国地质大学(北京),北京100083 [2]北京矿产地质研究院

出　　处：《地质与勘探》2006年第4期51-56,共6页Geology and Exploration

基　　金：中国科技部"973"项目(编号:2001CB409806);国家自然科学基金项目(编号:D0304-40273021)联合资助

摘　　要：大井锡多金属矿床含锡矿物为锡石和黄锡矿,产于3个成矿阶段和5种矿石类型中.从早到晚,即韧性变形阶段→锡石-毒砂-石英阶段→锡石-硫化物阶段（或黄铜矿-黄铁矿阶段）,主要含锡矿物锡石的化学成分,表现出SnO2逐渐升高而FeO、TiO2、Nb2O5、Ta2O5和In2O5依次跳跃式递减的特征,同时NiO和Ga2O5趋于升高.与一般脉状锡矿床相比,早阶段锡石富Ta而晚阶段锡石富Ti、Fe,表明早期的锡石更接近花岗质岩浆源特征而晚期锡石则明显具层控性质.锡石的组分变化特征与各阶段（内）从早到晚成矿温度递减有关.另一含锡矿物黄锡矿含As、Zn较高,仅出现于锡石-硫化物阶段,并在温度为220℃～320℃、硫逸度为10^-10.04×10^5～10^-13.44×10^5Pa的特定区间内淀出.两个阶段锡石的稀土元素特征分别与矿区次火山岩和林西组地层一致,表明早期锡石-毒砂-石英阶段中的锡主要来自次火山岩（如英安斑岩）,而晚期锡石-硫化物阶段中的锡可能主要来自林西组围岩（如粉砂岩）.Tin -bearing minerals in the Dajing tin -polymetallic deposit are cassiterite and stannite. Three mineralization stages and five ore types are recognized. The composition of cassiterite, dominant tin- bearing mineral, presents that SnO2 increases in the sequence of mineralization stages from shear - deformation, to cassiterite - quartz, and to cassiterite - sulfide （ or chalcopyrite - pyrite）, while the contents of FeO, TiO2 , Nb2O5, Ta2O5 , and In2O5 tend not to be continual but fluctuating decrease with increasing of NiO and Ga2O5. The early stage cassiterite is much richer in Ta and the later stage cassiterite is much poorer in Ti and Fe, compared with that in hydrothermal vein type tin deposits. This is interpreted to indicate that the component of early stage cassiterite more reflects a granitic magma source while the composition of later stage cassiterite has more obvious strata - bound features. The compositional variation of cassiterite corresponds with the decreasing of mineralizing temperature within each stage and between sequential stages from early to late. The other tin mineral like stannite, As and Zn - bearing, only occurs in cassiterite - sulfide stage which precipitates in specified temperature range between 220℃ and 320℃ and sulfur fugacity of 10^-10.04 × 10^5Pa ～ 10^-13.44 × 10^5Pa. The characteristics of REE in cassiterite from two stages are correspondence with that of subvolcanic rocks and the Linxi formation. It is suggested that tin carried in cassiterite - quartz stage might originate from subvolcanic dikes （ e. g. dacite porphyry） while in cassiterite - sulfide stage might be provided by waUrocks （ e. g. sihstone） from the Linxi formation of the upper Permian series.

关 键 词：大井锡多金属矿床 锡石 黄锡矿 锡矿化 内蒙古 

分 类 号：P618.44[天文地球—矿床学]