The Calculation and Use of Sulfide Metal Contents in the Study of Magmatic Ore Deposits: A Methodological Analysis
The Calculation and Use of Sulfide Metal Contents in the Study of Magmatic Ore Deposits: A Methodological Analysis
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DOI：
10.2113/0100289
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发表时间：
2001-10
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影响因子：
--
通讯作者：
A. Kerr
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文献类型：
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作者：
A. Kerr
岩浆硫化物成矿样品的基本金属和PGE含量通常与其硫化物含量相关，表明块状硫化物的金属含量在给定的远景或部分范围内基本保持不变。计算出的硫化物金属含量为矿产勘探和研究提供了有价值的信息，但很少有对这一过程的正式描述和分析。对于典型的磁黄铁矿-黄铜矿-镍黄铁矿混合物，硫化物金属含量最好使用一个假设值(35.7%S)来计算，单独考虑硫化物物种似乎没有什么好处。金属数据与硫的回归可能是最严格的方法，但并不总是实用的。在10%S以上，计算是非常可靠的，但较低的硫化物含量通常需要至少对非硫化物寄主金属进行一些修正。这种校正在S含量低于5%时和/或在富含橄榄石的样品中会变得显著。它们最好是通过质量平衡计算来实现，使用来自未矿化的主岩的浓度数据。硫、贱金属和前列腺素E的分析误差引入了显著的不确定度，这些误差通常是从分开的样品等分线测量的。硫化物金属含量的这些综合误差一般超过±10%，但在S含量较低时，误差进一步扩大。一般来说，必须谨慎处理含-lt；2.5%S的样品的数据，特别是对于PGE，其确切的寄主矿物可能未知。该方法在简单的品位潜力评估中的应用是简单的，但涉及贫硫化物样品的研究本身就更加复杂。对非硫化物寄主金属的数据校正不足或过度校正可能会导致硫化物金属含量与硫化物含量之间存在假负或正相关关系。由于后者本身可能与地质参数有关，例如侵入体内的深度，因此这种趋势可能会产生不适当的影响。这种相关性也有合理的地质原因，这些数据需要仔细评估，以区分真实的和人为的变化。在缺乏硫化物的样品中，传播的分析不确定度显著增加，在比较和对比来自不同地区或单位的数据时，也必须记住这一点。
The base-metal and PGE contents of samples from magmatic sulfide mineralization are commonly correlated with their sulfide contents, indicating that the metal contents of bulk sulfides remain approximately constant within a given prospect or part thereof. Calculated sulfide metal contents provide valuable information in mineral exploration and research, but there are few formal descriptions and analyses of the procedures. Sulfide metal contents are best calculated using an assumed value (35.7% S) for a typical pyrrhotite-chalcopyrite-pentlandite mixture, and there appears to be little advantage in accounting for sulfide species separately. Regression of metal data against sulfur is probably the most rigorous approach, but is not always practical. Above 10% S, calculations are very robust, but lower sulfide contents generally demand at least some correction for non-sulfide-hosted metals. Such corrections can become significant below 5% S, and/or in olivine-rich samples. They are best accomplished by mass-balance calculations, using concentration data from unmineralized host rocks. Significant uncertainties are introduced by analytical errors for sulfur, base-metals, and PGE, which are commonly measured from separate sample aliquots. These combined errors in sulfide metal contents generally exceed ±10%, but expand further at low S contents. In general, treatment of data from samples containing <2.5% S must be approached with caution, especially for PGE, for which the exact host minerals may not be known. Application of the method in simple grade-potential assessment is straightforward, but research studies involving sulfide-poor samples are inherently more complex. Under-correction or over-correction of data for non-sulfide-hosted metals can lead to false negative or positive correlations between sulfide metal contents and sulfide content. As the latter may itself be linked to geological parameters, such as depth within an intrusive body, undue significance could be ascribed to such trends. There are also valid geological reasons for such correlations, and such data require careful assessment to separate true and artificial variations. Propagated analytical uncertainties increase significantly in sulfide-poor samples, and must also be borne in mind whenever data from different localities or units are compared and contrasted.