TY - JOUR A1 - Kaiser, Bjoern Onno A1 - Cacace, Mauro A1 - Scheck-Wenderoth, Magdalena A1 - Lewerenz, Bjoern T1 - Characterization of main heat transport processes in the Northeast German Basin constraints from 3-D numerical models JF - Geochemistry, geophysics, geosystems N2 - To investigate and quantify main physical heat driving processes affecting the present-day subsurface thermal field, we study a complex geological setting, the Northeast German Basin (NEGB). The internal geological structure of the NEGB is characterized by the presence of a relatively thick layer of Permian Zechstein salt (up to 5000 m), which forms many salt diapirs and pillows locally reaching nearly the surface. By means of three-dimensional numerical simulations we explore the role of heat conduction, pressure, and density driven groundwater flow as well as fluid viscosity related effects. Our results suggest that the regional temperature distribution within the basin results from interactions between regional pressure forces as driven by topographic gradients and thermal diffusion locally enhanced by thermal conductivity contrasts between the different sedimentary rocks with the highly conductive salt playing a prominent role. In contrast, buoyancy forces triggered by temperature-dependent fluid density variations are demonstrated to affect only locally the internal thermal configuration. Locations, geometry, and wavelengths of convective thermal anomalies are mainly controlled by the permeability field and thickness values of the respective geological layers. KW - advection KW - convection KW - coupled fluid and heat transport KW - numerical simulations KW - Northeast German Basin KW - salt structures Y1 - 2011 U6 - https://doi.org/10.1029/2011GC003535 SN - 1525-2027 VL - 12 IS - 13 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Kaiser, Björn Onno A1 - Cacace, Mauro A1 - Scheck-Wenderoth, Magdalena T1 - Quaternary channels within the Northeast German Basin and their relevance on double diffusive convective transport processes - constraints from 3-D thermohaline numerical simulations JF - Geochemistry, geophysics, geosystems N2 - The internal geological structure of the Northeast German Basin (NEGB) is affected by intense salt diapirism and by the presence of several stratified aquifer complexes of regional relevance. The shallow Quaternary to late Tertiary freshwater aquifer is separated from the underlying Mesozoic saline aquifers by an embedded Tertiary clay enriched aquitard (Rupelian Aquitard). An important feature of this aquitard is that hydraulic connections between the upper and lower aquifers do exist in areas where the Rupelian Aquitard is missing (hydrogeological windows). Three-dimensional thermohaline numerical simulations are carried out to investigate the effects of such hydrogeological windows in the Rupelian Aquitard on the resulting groundwater, temperature, and salinity distributions. Numerical results suggest that hydrogeological windows act as preferential domains of hydraulic interconnectivity between the different aquifers at depth and enable vigorous heat and mass transport which causes a mixing of warm and saline groundwater with cold and less saline groundwater within both aquifers. In areas where the Rupelian Aquitard confines the Mesozoic aquifer, dissolved solutes from major salt structures are transported laterally giving rise to plumes of variable salinity content ranging from few hundreds of meters to several tens of kilometers. Furthermore, destabilizing thermal buoyancy forces may overwhelm counteracting stabilizing salinity induced forces offside of salt domes. This may result in buoyant upward groundwater flow transporting heat and mass to shallower levels within the same Mesozoic Aquifer. KW - double diffusive convection KW - thermohaline processes KW - numerical simulations KW - salt structures KW - Northeast German Basin KW - quarternary channels Y1 - 2013 U6 - https://doi.org/10.1002/ggge.20192 SN - 1525-2027 VL - 14 IS - 8 SP - 3156 EP - 3175 PB - American Geophysical Union CY - Washington ER -