摘要
方解石是若尔盖铀矿田与成矿最为密切的脉石矿物之一。方解石的REE地球化学特征研究表明,产于地层中的方解石、矿区中的方解石和含矿方解石具有明显不同的稀土元素组成特征,分别具有轻稀土富集右倾型、重稀土富集左倾型和相对平坦型的3种稀土配分模式。其中产于地层中的方解石明显继承了地层中岩石的稀土元素特征,而含矿方解石表现出与矿石稀土元素相似的特征。碳氧同位素显示地层中的方解石为海洋沉积碳酸盐岩的碳氧同位素组成特征;矿区方解石脉、含矿方解石脉的碳同位素组成明显表现为地幔来源的特点;而矿区方解石脉的氧同位素组成具明显的深部来源特征,含矿方解石脉的氧同位素组成表明在成矿过程中有大气降水的混入。若尔盖铀矿田的方解石主要为热液成因,其矿床成因类型属于典型的热液矿床,成矿流体主要来源于地幔。
Calcite is one of the main gangue minerals in the Zoige Uranium Ore Field,which has a most close relation with uranium mineralization.Based on analyzing geochemistry characteristics of REE of calcite in strata,calcite in the mine area and ore-bearing calcite,their REE model is characterized by enrichment in light REE（decline to right）,heavy REE（decline to left） and relatively flat of REE distribution patterns,respectively.Among them,calcite in strata shows the characteristics of the obvious inheritance of the sedimentary rocks,while the characteristics of rare earth elements of the ore-bearing calcite are similar to those of the ore-stone.Carbon-oxygen isotopic characteristics of calcite in strata shows the carbon-oxygen compositions of marine carbonate rocks,while the other two implying an involvement of mantle derived source.Oxygen isotopic characteristics suggests existence of deeply-derived fluid for the calcite in the mine area,while oxygen isotopic characteristics of ore-bearing calcite show the evident addition of some introduced fluids possibly from infiltrating atmospheric water into the ore-forming fluids.Calcite in Zoige Uranium Ore Field is mainly of hydrothermal origin,and the type of the genesis is a typical hydrothermal deposit with its ore forming fluid originated from mantle.
出处
《地球科学进展》
CAS
CSCD
北大核心
2012年第10期1061-1067,共7页
Advances in Earth Science
基金
国家自然科学基金项目"若尔盖地区碳硅泥岩型铀矿床垂直分带规律研究"(编号:41072064)资助
关键词
方解石
稀土元素
碳氧同位素
若尔盖铀矿田
Calcite
Rare earth elements（REE）
Carbon-oxygen isotopes
Zoige Uranium Ore Field.
