Geochemical Characteristics of a Veinlet Kupferschiefer Profile from the Lubin Mine, Southwestern Poland

Abstract

AbstractPrevious studies have shown that the ascending, oxidizing brines play a very important role in Kupferschiefer mineralization. Fractures could be the pathway of the brines. In order to clarify the influences of the brines on bulk organic matter, aromatic hydrocarbons and Kupferschiefer mineralization, one veinlet Kupferschiefer profile from the Lubin mine, southwestern Poland was studied with the microscopic, geochemical and Rock‐Eval methods. The microscopic results indicate that organic matter of the veinlet sample consists dominantly of bitumen. Its extract content is higher than in other samples. The dominant aromatic compounds are naphthalene and alkylated naphthalenes (Na‐PAH), which have migrated into the veinlet sample from other sediments. The content of phenanthrene and its methylated derivatives (Ph‐PAH) is much lower than in other samples. The reason may be due to their heavier mass than Na‐PAH. It is more difficult for Ph‐PAH to migrate. The Na‐PAH was probably removed from the shale by distillation and enriched in fractures because of their relatively low boiling point. The content of biphenyl and alkylated biphenyls (Bi‐PAH) indicates the influence degree of oxidizing fluids. Their content in the veinlet sample is higher than in other sample. The high Tmax value of the veinlet sample also reveals a more intense influence of the oxidizing fluids than in other samples. Besides the higher Tmax value, its HI value is higher than in other samples. One can presume that its original hydrocarbon content should be higher than this value because they could be partly depleted by the brines.Five elements (As, Mo, Co, Ni and Bi) are enriched in the veinlet sample, perhaps due to the higher content of extractable bitumen in the fracture, particularly, the high content of Na‐PAH. The higher concentration of the five selected elements indicates that the Kupferschiefer mineralization of veinlet type occurred after the Kupferschiefer deposition.