重庆高燕锰矿床含锰碳酸盐岩稀土元素特征

摘要

重庆城口高燕锰矿属于大型碳酸盐锰矿床.文章在系统野外地质调查及样品采集基础上,结合前人研究工作,采用等离子质谱仪(ICP-MS)分析了高燕矿区师家沟、板相沟及750平硐样品的稀土元素含量.分析结果显示,其稀土元素总量范围49.79×10-6～281.24×10-6,平均含量125.92×10-6;轻重稀土比值范围1.79～3.58,显示轻稀土元素富集,且轻稀土元素之间的分馏程度高于重稀土元素;w(La) /w(Ce) =0.36～0.93,δEu=1.13～2.96,呈现弱正铕异常;δCe=2.09～5.84,有强的正铈异常.认为含锰碳酸盐岩形成于强还原的碱性环境沉积过程中,且有热水参与,成岩成矿的温度小于250℃,锰富集阶段处于滨岸的高能环境中.Ces＜10在本区具有示矿作用.%Gaoyan Mn deposit is a large carbonate rock type deposit.Previous results and ICP-MS analysis of samples systematically collected from Shijiagou,Banxianggou and adit 705 show that the total w (REE) is 49.79 × 10 6 ～281.24× 10-6,the average 125.92 × 10-6.w(LREE)/w(HREE) is 1.79～3.58,light REE enrichment,and higher fractionation of LREE than HREE,w(La)/w(Ce)=0.36～0.93,δEu =1.13～2.96,weak Eu anomaly,δCe is 2.09～5.84,strong positive cerium anomaly.We consider that manganese carbonate formed in strong reducing alkaline environment incorporated with hot water,the rock-forming and ore-forming temperature less than 250℃,the manganese enrichment under high-energy environment.Ces＜10 is indicator of ore in the district.