Phosphorus in different types of ore, sulfides in the iron deposits, and the type and origin of ores at Kiruna
Phosphorus in different types of ore, sulfides in the iron deposits, and the type and origin of ores at Kiruna
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不同类型矿石中的磷、铁矿床中的硫化物以及基律纳矿石的类型和来源
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发表时间：
1985
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通讯作者：
T. Parák
中科院分区：
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作者：
T. Parák
在基伦型铁矿中，磷灰石被认为是最显眼的矿物。基律纳岩浆侵位模式的倡导者认为，磷灰石是从母矿浆结晶而来的。然而，对归类为基律纳类型矿石的矿床的仔细研究表明，它们既包括含磷灰石的矿体，也包括几乎不含磷灰石的矿体或部分矿体。总体而言，这意味着磷灰石在这类矿石中分布不均匀。然而，沿着个别层或条带，磷灰石的分布是持久的。在这方面，基鲁纳型矿石与其他类型的矿石有相似之处。类似于富含磷灰石的基鲁纳型矿石的磷灰石条带，即使在地质上与基鲁纳型矿石地质相似的其他矿石类型中，也是有文献记载的成分。基鲁纳瓦拉矿体中有多个矽卡岩型矿石、条带状铁矿型矿石和块状层状硫化矿石，其磷含量与基鲁纳型矿石中的富磷矿点一样高。基鲁纳瓦拉矿体还包括电气石和硫化物，以黄铁矿浸染矿石的形式存在，以及含有铜、B、P、W和Au的黄铁矿-磁铁矿矿脉。另一方面，地层学上位于基鲁纳瓦拉矿体下方的维斯卡里亚铜矿床也略微富含磷灰石。在Kiirunavaara矿体中，夕卡岩带状矿石直接位于磷灰石带状矿石的下方。几个铁矿石矿床被归类为基鲁纳型矿石，产于富含夕卡岩的火山沉积物容矿岩石中。在Malmberget铁矿的围岩中发现了富含磷灰石的黄铜矿、黄铁矿和磁黄铁矿“灰色轻铁矿”。莱韦涅米铁矿主要产于沉积岩中。在Tjaarrojaakka共生的铁铜矿床中，磷含量往往很高。在瑞典北部，基鲁纳型矿石下方的矿石和围岩中也有磷灰石的富集区。这些矿石被认为是沉积型的。作者认为，基律纳型矿石中磷灰石分带的先决条件是大规模的区域磷富集，而不是磷灰石岩浆在矿石中的注入。瑞典北部基律纳型矿床中铁和硫化物的一个可能来源是该地区的细辉绿岩。绿岩既有磁性的，也有非磁性的。在基律纳，30公里2的非磁性绿岩区域是更大的磁性绿岩带的一部分。这些非磁性绿岩中的铁含量每减少1%，就足以生产24亿吨磁铁矿。其他矿石成分，如磷和稀土元素，其来源与基伦型矿石下绿岩中沉积夹层中发现的这些元素的富集性相似。当基律纳型矿石与块状层状硫化物矿石进行比较时，许多相似之处显而易见。包括：矿体形态、地层、矿壁岩石接触关系、与火山岩的成因组合、矿石内部特征，甚至某种程度上的地球化学。例如，铁是主要金属；两种类型的矿石中都有矿石浸染和矿石角砾化；两种类型的矿床中都存在方解石和其他蚀变现象。所谓的磁铁正长斑岩和基鲁纳主要矿床下盘附近的蚀变岩石，大多是硅化的，被解释为水道或网状矿化。
In the Kiruna-type iron ores, apatite has been regarded as the most conspicuous mineral. Advocates of the magmatic-intrusive mode of ore emplacement at Kiruna have argued that the apatite crystallized from a parent ore magma. However, a closer examination of deposits classified as Kiruna-type ores shows that they include both apatite-bearing and virtually apatite-free orebodies or parts of orebodies. In general terms this means that apatite distribution is uneven in this type of ore. Along individual layers or bands, however, apatite distribution is persistent. In this respect, there are similarities between the Kiruna-type ores and other types. Apatite banding similar to the apatite-rich Kiruna-type ore is a documented component even in other ore types in environments geologically similar to those of the Kiruna-type ores. There are several examples of skarn-type ores, banded iron-formation-type ores, and massive stratiform sulfide ores where the phosphorus content is as high as in the phosphorus-rich occurrences of Kiruna-type ores.The Kiirunavaara orebody also includes tourmaline and sulfides in the form of pyrite-impregnated ore and pyrite-magnetite veins containing Cu, B, P, W, and Au. On the other hand the Viscaria copper deposit, which is situated stratigraphically below the Kiirunavaara orebody, is also slightly rich in apatite. Within the Kiirunavaara orebody, skarn-banded ore lies directly beneath the apatite-banded ore.Several iron ore deposits, classified as Kiruna-type ores, occur in skarn-rich, volcanic sediment-hosted rocks. Apatite-rich chalcopyrite, pyrite, and pyrrhotite-impregnated "gray leptite" is found in the wall rock of the iron ores at Malmberget. The Leveniemi iron ore occurs mainly in sedimentary rocks. In the coexisting iron-copper ore deposits at Tjaarrojaakka, high phosphorus contents are often found.In northern Sweden, there is also apatite enrichment in the ores and wall rocks which lie below the Kiruna-type ores. These ores are regarded as sedimentary. The present author believes that a prerequisite condition for apatite banding in Kiruna-type ores would be a large-scale regional enrichment of phosphorus, and not injection of apatite magma in the ores.A possible source of the iron as well as the sulfides in the Kiruna-type deposits of northern Sweden is the spilitic greenstone in the area. The greenstones show both magnetic and nonmagnetic varieties. A 30-km 2 area of nonmagnetic greenstones at Kiruna is part of a larger belt of magnetic greenstones. A decrease in the iron content in these nonmagnetic greenstones by 1 percent would be sufficient to produce 2.4 billion tons of magnetite ore. Other ore components, such as phosphorus and rare earth elements, originated in a way similar to the enrichment of these elements found in the sedimentary interlayers in the greenstones below the Kiruna-type ores.When the Kiruna-type ores are compared to the massive stratiform sulfide ores, many similarities are evident. These include: the shape of the orebodies, the stratigraphy, the ore-wall-rock contact relations, the genetic association with volcanic rocks, the internal features of the ores, and to some extent even the geochemistry. For example, iron is the main metal; there are ore impregnations and ore brecciation in both types of ores; and scapolitization and other alteration phenomena are common in both types of deposits.The so-called magnetite syenite porphyry and the altered, mostly silicified, rocks adjacent to the footwall of the main ore deposits at Kiruna are interpreted as channelway or stockwork mineralization.