Optimizing a Knowledge-driven Prospectivity Model for Gold Deposits Within Peräpohja Belt, Northern Finland
Optimizing a Knowledge-driven Prospectivity Model for Gold Deposits Within Peräpohja Belt, Northern Finland
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DOI：
10.1007/s11053-016-9321-4
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发表时间：
2017-01
影响因子：
5.4
通讯作者：
V. Nykänen;T. Niiranen;F. Molnár;I. Lahti;K. Korhonen;N. Cook;P. Skyttä
中科院分区：
文献类型：
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作者：
V. Nykänen;T. Niiranen;F. Molnár;I. Lahti;K. Korhonen;N. Cook;P. Skyttä
本文结合知识和数据驱动的前瞻性映射方法，通过使用受试者工作特征（ROC）的空间统计技术，以优化的过程中重新调整输入数据集和数据集成的过程中，使用模糊逻辑前瞻性映射方法。该方法在芬兰北方芬诺斯堪的地盾古元古代Peräpohja带（PB）的一个活跃的矿产勘探区进行了测试。PB包括绿片岩到角闪岩相、复杂变形的表壳序列的可变石英岩、镁铁质火山岩和火山碎屑岩、碳酸盐岩、黑色页岩、云母片岩和杂砂岩。这些地层是在太古代基底（2.44- 1.92Ga）多次裂陷作用期间，沉积于太古代基底和2.44Ga层状侵入体之上的。PB中较年轻的侵入单元包括2.20-2.13 Ga的辉长岩床或脉和1.98 Ga的A型花岗岩。变质和复杂的变形发生在Svecofennian造山运动（1.9-1.8 Ga），其次是造山后花岗岩类（1.81-1.77 Ga）的侵入。最近的矿产勘探活动表明，在PB内有几个含金矿物。隆帕斯金铀矿化产于变形变质的钙硅酸盐脉中，这些脉封闭在镁铁质火山岩中，并含有不含金的含铀带和含有晶质铀矿和晶质铀矿-焦沥青结核的极高品位（> 10，000 g/t Au）金袋。在隆帕斯附近，帕洛卡斯-拉贾帕洛前景也发现了镁夕卡岩型浸染状网脉金矿化。转化为模糊逻辑远景模型的勘探标准包括从区域冰碛地球化学（Fe、Cu、Co、Ni、Au、Te、K）、高分辨率航空地球物理学（磁场总强度、电磁、伽马辐射）、地面重力和区域基岩图（结构）得出的数据。目前的黄金勘探许可证和勘探钻井现场被用来验证知识驱动的矿产远景模型。
This paper combines knowledge- and data-driven prospectivity mapping approaches by using the receiver operating characteristics (ROC) spatial statistical technique to optimize the process of rescaling input datasets and the process of data integration when using a fuzzy logic prospectivity mapping method. The methodology is tested in an active mineral exploration terrain within the Paleoproterozoic Peräpohja Belt (PB) in the Northern Fennoscandian Shield, Finland. The PB comprises a greenschist to amphibolite facies, complexly deformed supracrustal sequence of variable quartzites, mafic volcanic rocks and volcaniclastic rocks, carbonate rocks, black shales, mica schists and graywackes. These formations were deposited on Archean basement and 2.44 Ga layered intrusions, during the multiple rifting of the Archean basement (2.44–1.92 Ga). Younger intrusive units in the PB comprise 2.20–2.13 Ga gabbroic sills or dikes and 1.98 Ga A-type granites. Metamorphism and complex deformation of the PB took place during the Svecofennian orogeny (1.9–1.8 Ga) and were followed by intrusions of post-orogenic granitoids (1.81–1.77 Ga). The recent mineral exploration activities have indicated several gold-bearing mineral occurrences within the PB. The Rompas Au-U mineralization is hosted within deformed and metamorphosed calc-silicate veins enclosed within mafic volcanic rocks and contains uranium-bearing zones without gold and very high-grade (>10,000 g/t Au) gold pockets with uraninite and uraninite-pyrobitumen nodules. In the vicinity of the Rompas, a magnesium skarn hosted disseminated-stockwork gold mineralization was also recognized at the Palokas-Rajapalot prospect. The exploration criteria translated into a fuzzy logic prospectivity model included data derived from regional till geochemistry (Fe, Cu, Co, Ni, Au, Te, K), high-resolution airborne geophysics (magnetic field total intensity, electromagnetic, gamma radiation), ground gravity and regional bedrock map (structures). The current exploration licenses and exploration drilling sites for gold were used to validate the knowledge-driven mineral prospectivity model.