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莫桑比克楠普拉省喀祖祖地区多条河流均有人工砂金开采活动.砂金分布在海拔300～450 m之间的石英砾石层,底部岩石主要为中元古代片麻状杂岩体.研究区为准平原-丘陵地貌,水动力条件受季节影响较大.砂金分布与河流不存在明显的耦合性,暗示了原生金矿化可能较分散.同时,研究区露头受第四纪覆盖严重,物化探效果不显著,砂金与重砂矿物组合因而成为重要的原生金找矿标志.结合双目镜观察及扫描电镜分析得出,与砂金密切相关的重砂矿物包括黄铁矿、钛铁矿、锆石等.砂金颗粒多呈棱角状,部分可观察到残留连生矿物,整体暗示了近源堆积的特征.根据电子探针分析结果,不同部位产出砂金成分相近,表现为较高的金成色(w(Au)均高于98％)及较低的微量元素(仅含少量Fe、Cu),暗示为同一构造背景下的产物.综上,莫桑比克楠普拉省喀祖祖地区原生金矿化可能是与黑云斜长片麻岩(及其长英质脉体)相关的低硫型热液金矿化,形成背景为泛非期造山运动. 相似文献
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This article deals with the interaction of zinc with δ-MnO2,γ-MnOOH and manganite existing in natural water systems. The mechanism of the reaction has been studied in detail. From the fact that the "ratio of ion exchange (%)-pH" graph is an "S shaped" curve, it is possible to deduce that the chemical reaction is of the nature of cation exchange. And since the pH range of ion exchange = 4, it is possible to further deduce that the reaction can be explained by the mechanism of monovalence cation exchange.The main result of this article is the discovery of a new type of isotherm which has not been mentioned in previous literature here and abroad. This isotherm cannot be represented by any presently available adsorption isotherm equations in marine chemistry. The characteristics of this new type of isotherm are as follows: the isotherm has two "knees" and three "plateaus", the heights of these three "plateaus" are in the ratio 1:2:3. In order to explain theoretically our new isotherm, this article suggest 相似文献
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