云南临沧花岗岩离子吸附型稀土矿床地球化学特征及其成因讨论

【研究目的】临沧花岗岩风化壳广布,离子吸附型稀土资源潜力巨大。加强对临沧花岗岩风化壳离子吸附型稀土相态特征、浸出率等矿床地球化学特征和成矿机制的研究有利于进一步促进该区离子吸附型稀土资源的找矿工作。【研究方法】本文选择临沧花岗岩中段地区,通过系统实施钻探工程,详细了解稀土成矿地质及矿床地球化学特征,并对其成因进行探讨。【研究结果】临沧花岗岩风化壳全风化层稀土全相及浸出相稀土元素分异强烈,配分曲线呈右倾平滑的“W”型,稀土矿石类型为轻稀土元素富集的混合型稀土矿;稀土矿体赋存在花岗岩风化壳的全风化层,品位变化由上至下呈现出“上低—下高”和“上高—下低”两种类型。【结论】下渗的酸性溶液携带从花岗岩副矿物中解离出来的稀土离子向下运移,在风化壳的全风化层富集成矿,由于半风化层和弱风化层黏土矿物和酸性溶液的急剧减少,稀土元素富集程度大大降低。

Geochemical characteristics and genesis of ion-adsorption type REE deposit in the Lincang granite, Yunnan Province

This paper is the result of mineral exploration engineering.Objective]The widespread Lincang granite weathering crust has the enormous potential of ion-adsorption type REE resource. Strengthening the research on the phase characteristics and leaching rate of ion-adsorption type REE deposit in Lincang granite weathering crust and other ore deposit geochemical characteristics and metallogenic mechanisms will help to further promote the prospecting of ion-adsorbed rare earth resources in this area. Methods]Through systematic drilling projects in the middle section of Lincang granite, a detailed understanding of rare earth metallogenic geology and ore deposit geochemical characteristics, and its genesis are discussed. Results]All-phase and leaching-phase of REE in the full weathering layer of crust are strongly differentiated, their distribution patterns show "W" shapes as smooth and shallow; the ores are the mixed type of LREE-enriched; REE ore bodies lay in the full weathering layer of granite weathering crust, and grade changes from top to bottom show two types as " low- high" and " high- low". Conclusions]The infiltrating acidic solution carries the REE which dissociate from the sub-minerals of granite migrating down, the REE enrich and mineralize in the full weathering layer of crust, because the clay minerals and acidic solutions declined sharply, the enrichment of half weathered layer and weak weathered layer are greatly reduced.Highlights: The leaching characteristics of ion- adsorption type REE deposit in Lincang granite weathering crust show that the leaching rate is stable at 55%-75%; Establish the metallogenic mechanism and metallogenic model of ion-adsorption type REE deposit.