乌干达苏库卢碳酸岩风化壳成矿元素地球化学评价指标

Geochemical Evaluation Indicators of Metallogenic Elements of the Sukulu Carbonatite Weathering Crust,Uganda

碳酸岩是一种特殊的火成岩,常与多种成因类型的矿床密切相关,故引起国内外学者的广泛关注。笔者以乌干达苏库卢碳酸岩风化壳为研究对象,选取区内典型剖面AB和钻孔ZK14(W),应用剖面地球化学异常和钻孔地球化学异常的方法总结了矿床的成矿规律和成因。笔者提出采用[w(Nb_2O_5)*w(REO)*w(TFe)*1000]/w(P_2O_5)累乘比值作为矿体剥蚀的判别指标(K_1),得出:强风化区K_1>500,半、弱风化区500>K_1>100,碳酸岩原岩K_1<100。同时,本文首次尝试为地球化学勘查理论适用于风化壳矿床提供勘查实例。

Carbonatite is a special kind of igneous rocks, and is closely associated with a variety of genetic types of deposits, which has aroused wide concern of scholars at home and abroad. Taken the Sukulu earbonatite weathering crust as an example, this work summarized the metallogenic regularity and genesis of this deposit by applying profile and drill hole geochemical anomalies to the selected typical profile AB and drillhole ZK14 （W）. A discrimi- nation index Kt which is equals to [w（Nb205） ＊ w（REO） ＊ w（TFe） ＊ 1000] /w （P2O5） is put forward to show the denudation of the ore bodies. The result shows that the strong weathering area has Kt 〉 500, the semi - weathering area has 500 〉 Kl 〉 100 and carbonatite protolith has K1 〈 100. In addition, this work provides an example to validate that geochemical exploration theory is suitable for weathering crust deposits.