Geochemistry of the Lublin Formation from the Lublin Coal Basin: Implications for weathering intensity, palaeoclimate and provenance

Abstract

The Lublin Formation (upper Westphalian A and Westphalian B) is the main coal-bearing series of the Lublin Coal Basin (LCB). So far, few geochemical studies of the Carboniferous of the LCB have been performed, and there is almost no data on the geochemistry of this series. This paper presents geochemical data for 118 samples from the Lublin Formation, from the central part of the LCB. Major oxide concentrations (Al2O3, SiO2, Fe2O3, P2O5, K2O, MgO, CaO, Na2O, K2O, MnO, TiO2, Cr2O3, Ba) were obtained using an X-ray fluorescence spectrometry. Trace and major elements (Zr, Th, Sc, La, U, Cu, Sr, Rb, Ni, Fe, Mn, Ca, Mg, K, Na) were analysed using inductively-coupled plasma mass spectrometry.Concentrations of the major and trace elements showed significant diversity, especially in the Westphalian B deposits. The Chemical Index of Alteration, Plagioclase Index of Alternation, and Weathering Index of Parker values, as well as the Rb/Sr, Sr/Cu, C and Th/U ratios of the studied samples suggest a high degree of chemical weathering of the source rocks and a prevailing warm, humid climate with some arid episodes. Based on indicators such as Al2O3/TiO2, TiO2/Zr and La/Th, it is suggested that all the studied samples from the Lublin Formation of the LCB were derived from felsic to intermediate igneous rocks, while the Th/Sc ratio suggests a mixed source for these sediments.