MODELOWANIE PRZEMIAN SKŁADU CHEMICZNEGO WÓD PODZIEMNYCH PERMSKIEGO PIĘTRA WODONOŚNEGO W REJONIE LUBIŃSKO-GŁOGOWSKIEGO OBSZARU MIEDZIONOŚNEGO

Abstract

GEOCHEMICAL MODELLING OF GROUNDWATER IN PERMIAN (ZECHSTEIN) AGUIFER IN THE LUBIN–GŁOGÓW COPPER REGION (LGCR)

Abstract. The Lubin–Głogów Copper Region (LGCR) is an area of copper mining, where ore sediment is exploited at depths of 600–1200 m. Mine dewatering has influenced the Triassic, Permian, Paleogene (Oligocene) and Neogene (Early and Middle Miocene) aquifers. In the north of LGCR outcrops of carbonate-rock aquifer underlies the Triassic and Oligocene sediments, whereas in the south it dips beneath Tertiary sediments. Six chemical water types were identified in the carbonate-rock aquifer: Cl–Na, Cl–Na–Ca, Cl–SO₄–Ca–Na, SO₄–Cl–Ca–Na, SO₄–Ca–Na and SO₄–HCO₃–Ca–Na. Generally, the total dissolved-solids concentration of water increases with depth. The predominance of sulphate over calcium and bicarbonate indicates that process controlling the chemistry of this water types is sulphate dissolution which involves dedolomitization of carbonates. Mining drainage forces groundwater moving through the Zechstein sediments initially dissolves anhydrite (or gypsum) and dolomite. The state of geochemical equilibrium, inverse mass balance and reaction path models in the carbonate-rock aquifer were calculated by using the computer model PHREEQC ver. 2.15.