Burial and thermal history of the Intra-Sudetic Basin (SW Poland) constrained by 1-D maturity modelling - implications for coalification and natural gas generation

mainly determined by the thermal evolution of the basin, which is usually directly related to its burial history. The thermal maturity pattern of the organic matter (degree of coalification, coal rank) is therefore directly related to the burial history of the stratigraphic section analyzed, and the heat transport through the rocks (e.g. Hantschel & Kauerauf 2009). The Intra-Sudetic Basin (ISB) is well-known for its bituminous and anthracite coal deposits occurring in deep, strongly faulted synclines (Kwiecińska 1967; Lipiarski 1976; Mastalerz & Jones 1988; Bossowski 1995; Kwiecińska & Nowak 1997; Nowak 1993, 1996, 1997, 2000; Uglik & Nowak 2015; Pešek & Sivek 2016). Coal was mined in two districts in Poland, Wałbrzych and Nowa Ruda, and in one in the Czech Republic (Žacléř district). Mining operations began in the nineteenth century and the coal mines were all closed by 1999, although there is some potential for further coal and anthracite exploitation. The complicated geological setting (e.g. faults, the steep dips of the upper Carboniferous coal-bearing strata, magmatic events), the abundance of gases (mainly methane and carbon dioxide) and related hazards of methane explosions or gas and rock outbursts, however, make traditional underground coal production uneconomic (Kotarba & Rice 2001; Sechman et al. 2013, 2017). The ISB is a relatively rare case of basin in which a par t icularly high thermal regime resulting from magmatic processes governed a coalification processes. The thermal history and coalification processes of the ISB have, however, seldom been studied (Kułakowski 1979, Mastalerz & Jones 1988, Botor et al. 2020). One of the major products of coalification is methane, and although the coalbed methane reserves in the ISB have not yet been estimated precisely, it might be worthy of exploitation. The distribution and migration of these gases is related to the thermal history of the ISB, and therefore our new findings also contribute to a deeper understanding of this relationship, which might allow for a better prediction of natural gases within sedimentary sequence. The main aim of this study is therefore to improve understanding of the thermal conditions which caused coalification processes in the ISB. This paper is based solely on the kinetic maturity modelling of vitrinite reflectance data which is adopted from previous papers (Chruściel et al. 1985; Bossowski 1997, 2001; Nowak 2000; Ihnatowicz 2001; Botor et al. 2020). The maturity modelling takes into account recent lowtemperature thermochronology results (Sobczyk et al.