The origin of formation waters in the abandoned Konrad iron ore mine (Salzgitter, Germany)
Brammer, Klaus-Jorgen; Knipping, Bernhard Josef
European Journal of Mineralogy Volume 5 Number 4 (1993), p. 787 - 798
published: Jul 22, 1993
manuscript accepted: Apr 9, 1993
manuscript received: Aug 28, 1992
ArtNo. ESP147050504018, Price: 29.00 €
Abstract In the abandoned Konrad iron ore mine near Salzgitter, Germany, an underground repository for low-level and intermediate radioactive waste is planned in a Jurassic iron ore body. For the critical examination of the long-term safety of this disposal the elemental composition of formation waters and the sulfur isotope composition of dissolved sulfates in the formation waters were used to discuss their origin. The δ34S values of the dissolved sulfate lie between + 21 %o and + 40 %o (rel. CDT, Canyon Diablo Troilite standard). Bacterial sulfate reduction is shown by the relationship between the absolute sulfate concentration and δ34S values of the dissolved sulfate. Further a possible primary δ34S value (about + 16 ‰ ) was obtained using the relationship between the sulfur isotope composition and absolute sulfate concentration. This value agrees with published data on the sulfur isotope composition of sulfate in Jurassic evaporites (e.g., Nielsen, 1979). Due to the high bromine concentration of about 375-825 μg Br/g solution the formation waters cannot have originated by dissolution of marine evaporites. The sulfur isotope and chemical composition show that the studied formation waters are Jurassic sea water trapped in pore spaces during sedimentation.