Milička J., Pereszlényi M. & Macek J., 2025: Origin of natural asphalt in Mercury deposit Merník, East Slovakia. Acta Geologica Slovaca, 17, 2, 87–104.

Origin of natural asphalt in Mercury deposit Merník, East Slovakia

Ján Milička¹, Miroslav Pereszlényi² & Juraj Macek^1,3

¹Comenius University, Faculty of Natural Sciences, Department of Geochemistry, Ilkovičova 6, 842 15 Bratislava, Slovakia; jan.milicka@uniba.sk
²PC&G, Comenius University, Faculty of Natural Sciences, Ilkovičova 6, Mlynská dolina G, 842 15 Bratislava, Slovakia; pereszlenyi@pcg.sk
³Centre of Environmental Services, Ltd., Kutlíkova 17, 852 50 Bratislava, Slovakia; juraj.macek@uniba.sk

Abstract

During historical mining of cinnabar (HgS), an association of organic minerals, ozokerite and natural asphalt was identified. The occurrence of these solid hydrocarbons has been attributed to the presence of organic matter rich Neogene sediments of Karpatian and Badenian age exposed along the periphery of the Slanské vrchy Mountains. Thermal alteration of organic matter and subsequent hydrocarbon migration were most likely induced by elevated temperatures associated with intrusive magmatism and related hydrothermal processes. This study aims to evaluate the origin of the natural asphalt using detailed organic geochemical analyses (GC, GC–MS). Potential source rocks were evaluated based on the vertical and lateral distribution of sediments of the Central Carpathian Paleogene Basin (CCPB) in the Lipany-1 well area and, in the Prešov-1 well area, also of Lower Miocene sedimentary units. These successions were characterized using standard organic geochemical parameters, including total organic carbon (TOC), kerogen type, and thermal maturity indicators. Thermal maturity modeling of the CCPB sedimentary succession was performed and compared with measured vitrinite reflectance (Ro) data, which indicate that parts of the basin reached the oil window. The potential source to Merník asphalt relationship was evaluated based on steranes and triterpanes correlations. The biomarker data demonstrate that the natural asphalt from the Merník locality is genetically related to organic matter within the CCPB sediments. In contrast, nearby Lower Miocene sedimentary rocks in the northern part of the andesitic stratovolcano did not reached the sufficient thermal maturity for hydrocarbon generation and can therefore be excluded as effective source rocks.

Key words: East Slovakia, neovolcanics, rhyodacites, asphalt, source rocks, GC-MS correlations

Manuskript doručený: 2025-12-16

Manuskript revidovaný: 2025-12-29