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Title (Primary) Chemistry and isotopic composition of Rotliegend and Upper Carboniferous formation waters from the North German Basin
Author Lüders, V.; Plessen, B.; Romer, R.L.; Weise, S.M.; Banks, D.A.; Hoth, P.; Dulski, P.; Schettler, G.;
Journal Chemical Geology
Year 2010
Department ISOHYD; CATHYD;
Volume 276
Issue 3-4
Language englisch;
Keywords Formation water; Brines; North German Basin; D,O,N; Sr isotopes
Abstract Element concentrations and isotopic composition (dD, d18O, d15N of ammonium, 87Sr/86Sr) have been determined in highly-saline formation waters from the Rotliegend Altmark gasfield and the Upper Carboniferous Husum-Schneeren gasfield in the North German Basin. Both reservoirs have been covered by huge Zechstein evaporite caps since the Late Permian. Formation waters from the Altmark gasfield are characterized by high total dissolved solids and are enriched in d18O relative to meteoric waters and either show positive or negative dD values which typically follow the proposed dD vs. d18O paths for seawater evaporation. Formation waters stored in Upper Carboniferous sandstones show much more variable element concentrations and d18O and dD values than the Rotliegend Formation waters. The Br vs. Cl concentrations of the brines suggest seawater evaporation being the principal source of salinity at both sites. The ammonium concentrations in the analyzed brines are highly variable and the d15N isotopic composition of dissolved ammonium is controlled either by the isotopic composition of the gas in the reservoir (Rotliegend) or that of the host rocks (Upper Carboniferous). At both sites, early formation waters interacted with the sedimentary host rocks after deposition. 87Sr/86Sr ratios suggest that re-equilibration between fluids and their host rocks occurred in pre-Triassic times. There is no chemical or isotopic evidence that original formation waters which occur in sandstone below the overlying Zechstein evaporites were flushed out or mixed by later meteoric water as has been documented in deep-seated Mesozoic and other Paleozoic aquifers of the North German Basin.
ID 10269
Persistent UFZ Identifier
Lüders, V., Plessen, B., Romer, R.L., Weise, S.M., Banks, D.A., Hoth, P., Dulski, P., Schettler, G. (2010):
Chemistry and isotopic composition of Rotliegend and Upper Carboniferous formation waters from the North German Basin
Chem. Geol. 276 (3-4), 198 - 208