广西龙江矿区离子吸附型稀土矿成矿规律对比

Metallogenic regularity comparison of rare earth elements deposits of ion-adsorption type in Longjiang of Guangxi

广西龙江矿区为离子吸附型稀土矿床,其母岩丰度、矿源岩稀土元素赋存状态、气候、p H值、地下水的渗透、构造等有利的成矿条件使得稀土矿得以形成和保留。由于局部地质条件的不同,同一地区的矿床特征又各有差异。经对比研究认为,龙江地区相对小平山地区矿源岩矿物颗粒粗、p H值（龙江地区为5.37~6.34,小平山地区为6.12~7.34）低,造成两区矿层的赋矿层位不同;龙江地区有效吸附稀土离子多,矿体埋藏相对较深,因此物质来源较多,相对小平山地区其矿体厚度大、品位高;由于地表稀土元素的分馏作用,使得龙江地区配分曲线右斜斜率较小平山地区低,龙江地区δEu为0.25~0.43,平均为0.34,相对其矿源岩（0.55）具有一定的亏损;小平山地区δEu为0.45~0.80,平均为0.70,相对其矿源岩0.48的值表现为相对富集。

The rare earth elements deposit of ion-adsorption type is located at Longjiang mining area. The mineralization conditions,aparent rock abundance,rare earth elements occurrence state in ore source rocks,climate,p H value,groundwater infiltration and structural condition are suitable for the formation and retention of rare earth elements. Due to different local geological conditions,the deposit characteristics are also different even in the same area. According to the comparative study,mineral particles of ore source rocks are coarser and p H value（ Longjiang area of 5. 37- 6. 34,Xiaopingshan area of 6. 12- 7. 34） is lower in Longjiang area than those in Xiaopingshan area,resulting in different ore bearing strata. In Longjiang area with effective adsorption of rare earth ions,relatively deep buried orebody,and with more matter sources,the orebody of high grade is relatively thicker than that in Xiaopingshan area. Because of the surface fractionation,rare earth elements curve of the ore source rock at the right inclined slope of Longjiang area is smaller than that in Xiaopingshan area. Relative to ore source rock,δEu of ore is 0. 25- 0. 43 with an average of 0. 34,and relative to its ore source rock 0. 55,is relatively depleted in Longjiang area. However,δEu of ore is 0. 45- 0. 80 with an average of 0. 70,and relative to its ore source rock 0. 48,is relatively enriched in Xiaopingshan area.