黔中九架炉组富锂黏土岩系的风化成因及锂的富集规律

Weathering Origin and Enrichment of Lithium in Clay Rocks of the Jiujialu Formation,Central Guizhou Province,Southwest China

为厘清黔中地区下石炭统九架炉组铝质黏土岩系中锂的超常富集机制（Li2O平均含量0.21%,最高达0.74%）,为寻找锂资源提供新的途径,对黔中地区4个典型剖面进行了富锂黏土岩的主量、微量及稀土元素在剖面上的分布规律研究。结果表明,下石炭统九架炉组与下伏寒武系娄山关群白云岩的不活动元素比值相同,且其稀土元素球粒陨石标准化配分模式相似,都以轻稀土富集的平缓右倾型为特征,暗示九架炉组的形成可能与下伏娄山关群白云岩的风化和酸不溶物的积累有关。元素相关性分析和风化作用强度指标研究发现,锂含量与CIA和Si/Al值皆呈负相关的关系。初步推测,泥质白云岩的风化分解,主量元素的大幅度流失,是造成锂超常富集的重要机制。

In order to clarify the supernormal enrichment mechanisms of Lithium（ Li） in clay rocks of the Lower Carboniferous Jiujialu Formation at central Guizhou Province（ averaging 0. 21%,and the highest concentration up to 0. 74%） and find a new approach to explore Li resources,we investigated the elemental distribution of four typical cross sections of Lirich clay rocks. Same ratios of immobile element pairs and similar LREE-rich REE distribution pattern of clay rocks in the carboniferous Jiujialu formation and underlying Cambrian Loushanguan group dolomites suggested that the Jiujialu Formation may result from weathering of underlying dolomites and accumulation of acidic insoluble matter. Correlation analysis and weathering intensity index showed that Li content was negatively correlated with the CIA index and Si/Al ratio. Therefore,weathering decomposition of argillaceous dolomite and substantial loss of major elements may play an important role in Li supernormal enrichment.