滇东南丘北县大铁铝土矿稀土元素特征研究

本文以丘北大铁铝土矿含铝岩系为研究对象, 通过ICP-MS分析测试, 研究了含铝岩系与下伏灰岩、玄武岩的稀土元素特征。研究结果表明, 丘北大铁铝土矿含铝岩系稀土配分模式曲线为向右倾斜的曲线, 与下伏马平组、黄龙组灰岩的稀土配分曲线相似, 而与峨眉山组玄武岩的稀土配分曲线相差较大; 灰岩具有较明显的Ce负异常和Eu负异常, 部分铝土矿和铁铝质岩具明显的Ce正异常和较明显的Eu负异常, 而多数铝土矿、铁铝质岩和铝质粘土岩则无明显的Ce、Eu异常。含铝岩系的稀土元素特征, 反映出其成矿物质来源于下伏灰岩而非玄武岩, 同时也反映出铝土矿的成矿物质来源于风化壳, 成矿物质搬运距离较近, 与海水的水合作用不甚明显。

REE Characteristics of the Datie Bauxite Deposit in Qiubei County, Northwest Yunnan Province

With the aluminum-bearing rock series of the Datie bauxite deposit in Qiubei County as the study object, the authors studied REE characteristics of aluminum-bearing rock series and underlying limestone and basalt by means of ICP-MS analysis. The results show that the REE patterns of aluminum-bearing rock series in the Datie bauxite deposit are right-oblique curves, which are similar to REE pattern curves of the underlying Maping For-mation and Huanglong Formation limestone but are quite different from the REE pattern curves of the Emeishan basalt. The limestone has fairly obvious Ce negative anomalies and Eu negative anomalies, some bauxite and fer-rallitic rocks have obvious Ce positive anomalies and fairly obvious Eu negative, whereas most bauxite, ferrallitic rocks and aluminous claystone have no obvous Ce and Eu anomalies. REE characteristics of the aluminum-bearing rock series suggest that the ore-forming materials were derived from the underlying limestone instead of from the basalt, that the ore-forming materials of the bauxite were sourced from the weathering crust with small transport distance, and that the mineralization had no evident relationship with the hydration of the sea water.