广西大厂锌铜矿方解石稀土元素地球化学特征

Rare Earth Elements Geochemical Characteristics of Sandbergerite Calcite in Dachang,Guangxi

方解石是广西大厂矿区常见的脉石矿物。测试了拉么矽卡岩型锌铜矿和铜坑矿床深部矽卡岩型锌铜矿方解石稀土含量,锌铜矿的稀土元素总含量普遍较低,稀土元素总量(ΣREE)=11.15×10-6~16.17×10-6,具有明显的有铕正异常,铕异常(δEu)为1.46~2.80,且轻重稀土分馏明显,轻稀土元素(LREE)/重稀土元素(HREE)为2.63~6.84,配分模式为具有铕正异常的轻稀土富集右倾型模式,这样的配分模式与锡多金属矿方解石稀土元素配分模式相似,暗示两者之间可能为同源不同阶段产物;且研究表明成矿流体来源为龙箱盖岩体岩浆结晶期后分异出的岩浆热液,成矿环境为还原环境过渡向氧化环境。

Calcite is a common gangue mineral in Dachang mining area.Previous studies on calcite of tin polymetallic ore in the upper part of the region are detailed,but the research on sandbergerite in the lower part has not been carried out.The calcite rare earth element content of Lamu skarn type sandbergerite and the skarn type of deep pit of Tongkeng deposit were tested.The results show that total content of the rare-earth element in sandbergerite are generally lower,total rare earth elements(ΣREE)is 11.15×10-6~16.17×10-6,europium has positive anomaly,europium anomalies(δEu)is 1.46~2.80,and light and heavy rare earth obvious fractionation,light rare earth element(LREE)/heavy rare earth element(HREE)is 2.63~6.84,distribution patterns with europium is abnormal enrichment of light rare earth right model,the distribution patterns and tin polymetallic calcite distribution patterns of rare earth elements are similar,which implies that they may be products of different stages of the same origin.The mineralization fluid is derived from magmatic hydrothermal fluid of longbulid magmatic crystallization period,and the mineralization environment is the transition from reduction environment to oxidation environment.