赣南葛藤嘴稀土矿风化壳剖面元素迁移特征研究

Characteristics of Element Migration in Weathering Crust Profile of Getenzui REE Deposits, Southern Jiangxi

近年来在赣南葛藤嘴地区首次报道了以浅变质岩为母岩的风化壳离子吸附型稀土矿床,这一发现极大地拓宽了离子吸附型稀土矿床的找矿空间。对赣南葛藤嘴浅变质岩离子吸附型稀土矿床的原岩与风化壳进行研究,共采集了3个变质沉凝灰岩原岩样品和12个风化壳剖面全风化层样品,开展元素地球化学特征分析,以探讨风化壳剖面中元素迁移与稀土元素富集特征。研究结果表明,风化壳风化程度已进入到风化中晚期,质量平衡计算显示其主量元素Ca、Na、P等元素基本淋滤殆尽,Si、Al、Mg、K迁出程度依次增强,Fe、Ti等元素保持相对稳定;稀土元素除Ce外,其他稀土元素均表现出明显的迁入特点;风化壳剖面全风化层样品的总稀土元素含量约为其原岩的3.4倍,稀土元素的富集主要由于原岩中富含稀土元素的矿物发生分解,释放的稀土阳离子在随地下水迁移过程中,被黏土矿物吸附导致。

In recent years, a ion-adsorption type REE deposits in the weathering crust with epi-metamorphic rock as parent rock has been reported for the first time in Getenzui area, Southern Jiangxi province, which greatly expands the prospecting space of ion-adsorption type REE deposits. In this paper, the parent rocks and weathering crust of the Getengzui ion-adsorption type REE deposits in southern Jiangxi were studied. We discussed that the characteristics of element migration and REE enrichment in weathering crust profiles through elements geochemical characteristics from 3 metamorphic tuff samples and 12 completely weathering samples. The results show that the weathering degree of weathering crust has entered the middle and late period.The mass balance calculation shows that the main elements Ca-Na-P are almost leached out, migration intensity of Si, Al, Mg and K are gradually increased, and Fe-Ti remain relatively stable. REE show obvious migration characteristics except Ce. The content of REE in the weathering crust was about 3.4 times that of the parent rock.The enrichment of REE was mainly due to the decomposition of rich-REE minerals and the adsorption by clay minerals during the migration of REE with groundwater.