Hydrogeologic and Thermal Effects of Glaciations on the Intracontinental Basins in Central and Northern Europe

Abstract

We use a fully coupled hydro-thermal model (TH) to quantify changes in the pore pressure and temperature distribution following the Last Glacial Maximum (LGM) in the intracontinental basins in Central and Northern Europe. We demonstrate that even without considering a direct mechanical coupling from the visco-elastic lithosphere rebound, the system is, at present-day, in a state of hydrogeologic and thermal disequilibrium as a result of the past ice sheet dynamics. We find that the local geology exerts an additional control on the subsurface response to imposed glacial loading, as evidenced by a contrasting thermal and pore pressure configuration in time and space. Highest rates of pore pressure dissipation are restricted to crustal domains that underwent substantial glacial loading, while the majority of the sedimentary sub-basins show a prominent signature of hydraulic disequilibrium (overpressure) at present. Groundwater-driven convective cooling and heating during the advance and retreat of the ice cap occurred mainly within sedimentary rocks, domains where thermal equilibration is ongoing. The spatial correlation between modeled pore pressure dissipation rates and postglacial uplift rates is indicative of a complex and transient hydrogeological system structurally connected to the viscous tail of the ongoing isostatic adjustment after the LGM, with important implications for assessing the long-term mechanical stability of this intraplate setting.

Modeling the influence of climate on groundwater flow and heat regime in Brandenburg (Germany)

“…The situation differs in regional groundwater system, which showcases an evidence of lateral outflow beyond the model domain (Supplementary Figure 5). However, these boundary effects can be considered of secondary relevance for current study, given that the internal flow geometries within the limits of Brandenburg are not significantly affected by our choice of open vs. closed boundary conditions, and, in principle, in agreement with a flow pattern obtained from the larger-scale model of CEBS (Frick et al, 2022;Supplementary Figure 5).…”

“…Due to the no-flow boundary along the model edge, groundwater leaves the aquifer via cross-flow to the adjacent units, eventually discharging at the surface. A larger basin model of the whole Northern Europe suggested that this deep groundwater flow actually continues north-west toward the most buried offshore parts of the NGB (Frick et al, 2022).…”

“…Under specific conditions (e.g., arid climate, high permeability, and steep relief) the water table may get disconnected from topography and become influenced predominately by recharge variability (Haitjema and Mitchell-Bruker, 2005). At the same time deep groundwater dynamics may carry memory effects from past climates, as evidenced in parts of Northern and Central Europe that are still in the process of pressure and temperature re-equilibration following the last glacial maximum, as suggested by postglacial seismicity (Sirocko et al, 2008), presence of relict permafrost in deep wells in Poland (Szewczyk and Nawrocki, 2011) and sub-glacial groundwater modeling (Frick et al, 2022). In order to understand the transient effects of such a complex non-linear system, we coupled a subsurface 3D groundwater model of Brandenburg with a near-surface distributed hydrologic model and simulated the 62-year-long behavior of the coupled dynamics of groundwater flow and thermal field.…”

Radiolytically reworked Archean organic matter in a habitable deep ancient high-temperature brine

“…This discrepancy includes larger concentrations of aromatic humic and fulvic acids, derived from current or recent mixing with pools of surface-photosynthate delivered to these shallower systems via groundwater recharge 7 , 8 . These hydrogeologic connections can be modern, or may reflect geologic processes, as in particular, paleo-recharge from past glacial cycles has been invoked as a global mechanism for enhanced penetration of surface waters into the near subsurface, sometimes to kilometers depth 9 , 10 . Subsurface systems can also contain much older biotic input if leaching occurs from proximal kerogen/bitumen rich ore deposits, such as the case with coal beds and oil field systems 11 .…”

Physical modeling of ice-sheet-induced salt movements using the example of northern Germany

“…The load of the ice sheets affected the Earth's crust and glacial isostatic adjustment (Lambeck et al, 2014), and processes such as postglacial rebound (Spada, 2017) or hydrogeological adaptations (Amberg et al, 2022;Frick et al, 2022) are still ongoing.…”