Geochemical characteristics of a veinlet Kupferschiefer profile from the Lubin mine, southwestern Poland

Previous studies have shown that the ascending, oxidizing brines play a ver y important role in Kupferschiefer mineralization. Fractures could be the p athway of the brines. In order to clarify the influences of the brines on b ulk organic matter, aromatic hydrocarbons and Kupferschiefer mineralization , one veinlet Kuperschiefer profile from the Lubin mine, southwestern Polan d was studied with the microscopic, geochemical and Rock-Eval methods. The microscopic results indicate that organic matter of the veinlet sample cons ists dominantly of bitumen. Its extract content is higher than in other sam ples. The dominant aromatic compounds are naphthalene and alkylated naphtha lenes (Na-PAH), which have migrated into the veinlet sample from other sedi ments. 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 w as probably removed from the shale by distillation and enriched in fracture s because of their relatively low boiling point. The content of biphenyl an d 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 T-max value of the veinlet sample also reveals a more intense inf luence of the oxidizing fluids than in other samples. Besides the higher T- max value, its III value is higher than in other samples. One can presume t hat its original hydrocarbon content should be higher than this value becau se they could be partly depleted by the brines. Five elements (As, Mo, Co, Ni and Bi) are enriched in the veinlet sample, p erhaps due to the higher content of extractable bitumen in the fracture, pa rticularly, the high content of Na-PAH. The higher concentration of the fiv e selected elements indicates that the Kupferschiefer mineralization of vei nlet type occurred after the Kupferschiefer deposition.