广西新联稀土矿区莲塘花岗岩的地质地球化学特征及成矿意义

摘要

Liantang granite mass of Xinlian rare earth mining area is formed in the Middle Jurassic.The gra nite mass is rich in Si,Na,K and Hf,but poor in Fe,Mg,Ca,P,Ni,Co,Cu,Zr,Sr,Ba and Ta,and it falls into the category of peraluminous high-K calc-alkaline series S-I transition type granite.The total rare earth averages at 185.39 × 10 -6 ,which is higher than the average Chinese granite of 147.80 ×10 -6 .The average ratio of LREE/HREE is 6.75,which indicates the enrichment of light rare earth.The weathering crust of granite mass is well developed.The different degrees of weathering result in different degrees of en-richment of rare earth elements.Rare earth ore bed occurs in the form of ion absorption within the middle part of completely weathered granite and upper part of semi-weathered granite.The rare earth mineralization is closely related to abundant rare earth content rock body,landform of low mountains and hills and climate, and the degree of weathering crust preservation.%新联稀土矿区莲塘花岗岩体形成于中侏罗纪,属于燕山期岩浆岩。该花岗岩体富 Si、Na、K、Hf,贫 Fe、Mg、Ca、P、Ni、Co、Cu、Zr、Sr、Ba、Ta,为过铝质高钾钙碱性系列 S-I 过渡型花岗岩；稀土总量的平均值为185.39×10-6,高于中国花岗岩均值147.80×10-6。轻重稀土的平均比值为6.75,表现为富集轻稀土。该花岗岩体的风化壳发育,由于风化程度不同,造成稀土元素的富集程度存在较大的差异。稀土矿层主要以离子吸附形式赋存于花岗岩全风化层中部及半风化层上部。该区稀土矿化与高丰度稀土含量的岩体、低山丘陵地貌条件及气候、风化壳保存程度等影响因素密切相关。