黔北北部铝土矿成矿物源碎屑锆石REE特征及成因探讨

REE characteristics of zircon from ore-forming detrital materials and discussion of genesis of the bauxite deposit in northern Guizhou

锆石中的稀土元素(REE)含量常用于判别锆石的成因类型,追索铝土矿的成矿物源。在道真县的铝土矿床中取样,对铝土矿中的碎屑锆石进行了LA-IPC-MS原位REE元素含量分析。REE元素含量变化范围很宽,HREE明显高于LREE,球粒陨石标准化配分模式分为3种类型,主要为HREE富集型+Ce正异常+Eu负异常,HREE相对平坦型+Ce正异常+Eu负异常,MREE亏损型+Eu负异常。铝土矿中碎屑锆石主要为岩浆锆石,其次为少量变质锆石和极少数热液锆石。铝土矿的成矿物源复杂,最终物源应主要来源于前寒武纪的岩浆岩,并与相应的地质事件有关。

The rare earth element （REE） content in the zircon is often used to distinguish the genetic types of zircon and to trace source of ore - forming materials of bauxite deposit. Based on REE content analysis result of zircon detritus samples collected from Daozhen bauxite deposit by LA - IPC - MS method, the REE content of zircon has a wide range, and HREE is significantly higher than LREE. Standardized REE distribution pattern of chondrites is divided into three types, mainly HREE enrichment ＋ Ce positive anoma- ly ＋ Eu negative anomaly, HREE flat ＋ Ce positive anomaly ＋ Eu negative anomaly, MREE loss ＋ Eu negative anomaly. The study shows that the zircons in the detritus are mainly originated from magmatic source in the bauxite deposit, mixed by small amounts of metamorphic zircons and few hydrothermal zircons. Therefore, source of the ore - forming material in the bauxite deposit is complicated, and the final source should come mainly from the Pro - Cambrian magmatic rocks and was associated with corresponding geological events.