TY - JOUR A1 - Freymark, Jessica A1 - Bott, Judith A1 - Cacace, Mauro A1 - Ziegler, Moritz 0. A1 - Scheck-Wenderoth, Magdalena T1 - Influence of the Main Border Faults on the 3D Hydraulic Field of the Central Upper Rhine Graben JF - Geofluids N2 - The Upper Rhine Graben (URG) is an active rift with a high geothermal potential. Despite being a well-studied area, the three-dimensional interaction of the main controlling factors of the thermal and hydraulic regime is still not fully understood. Therefore, we have used a data-based 3D structural model of the lithological configuration of the central URG for some conceptual numerical experiments of 3D coupled simulations of fluid and heat transport. To assess the influence of the main faults bordering the graben on the hydraulic and the deep thermal field, we carried out a sensitivity analysis on fault width and permeability. Depending on the assigned width and permeability of the main border faults, fluid velocity and temperatures are affected only in the direct proximity of the respective border faults. Hence, the hydraulic characteristics of these major faults do not significantly influence the graben-wide groundwater flow patterns. Instead, the different scenarios tested provide a consistent image of the main characteristics of fluid and heat transport as they have in common: (1) a topography-driven basin-wide fluid flow perpendicular to the rift axis from the graben shoulders to the rift center, (2) a N/NE-directed flow parallel to the rift axis in the center of the rift and, (3) a pronounced upflow of hot fluids along the rift central axis, where the streams from both sides of the rift merge. This upflow axis is predicted to occur predominantly in the center of the URG (northern and southern model area) and shifted towards the eastern boundary fault (central model area). Y1 - 2019 U6 - https://doi.org/10.1155/2019/7520714 SN - 1468-8115 SN - 1468-8123 PB - Wiley-Hindawi CY - London ER - TY - JOUR A1 - Heckenbach, Esther Lina A1 - Brune, Sascha A1 - Glerum, Anne C. A1 - Bott, Judith T1 - Is there a speed limit for the thermal steady-state assumption in continental rifts? JF - Geochemistry, geophysics, geosystems : G 3 ; an electronic journal of the earth sciences N2 - The lithosphere is often assumed to reside in a thermal steady-state when quantitatively describing the temperature distribution in continental interiors and sedimentary basins, but also at active plate boundaries. Here, we investigate the applicability limit of this assumption at slowly deforming continental rifts. To this aim, we assess the tectonic thermal imprint in numerical experiments that cover a range of realistic rift configurations. For each model scenario, the deviation from thermal equilibrium is evaluated. This is done by comparing the transient temperature field of every model to a corresponding steady-state model with an identical structural configuration. We find that the validity of the thermal steady-state assumption strongly depends on rift type, divergence velocity, sampling location, and depth within the rift. Maximum differences between transient and steady-state models occur in narrow rifts, at the rift sides, and if the extension rate exceeds 0.5-2 mm/a. Wide rifts, however, reside close to thermal steady-state even for high extension velocities. The transient imprint of rifting appears to be overall negligible for shallow isotherms with a temperature less than 100 degrees C. Contrarily, a steady-state treatment of deep crustal isotherms leads to an underestimation of crustal temperatures, especially for narrow rift settings. Thus, not only relatively fast rifts like the Gulf of Corinth, Red Sea, and Main Ethiopian Rift, but even slow rifts like the Kenya Rift, Rhine Graben, and Rio Grande Rift must be expected to feature a pronounced transient component in the temperature field and to therefore violate the thermal steady-state assumption for deeper crustal isotherms. KW - basin analysis KW - geodynamics KW - numerical modeling KW - rifting KW - thermal KW - modeling Y1 - 2021 U6 - https://doi.org/10.1029/2020GC009577 SN - 1525-2027 VL - 22 IS - 3 PB - Wiley CY - Hoboken, NJ ER - TY - JOUR A1 - Rodriguez Piceda, Constanza A1 - Scheck Wenderoth, Magdalena A1 - Gomez Dacal, Maria Laura A1 - Bott, Judith A1 - Prezzi, Claudia Beatriz A1 - Strecker, Manfred T1 - Lithospheric density structure of the southern Central Andes constrained by 3D data-integrative gravity modelling JF - International journal of earth sciences N2 - The southern Central Andes (SCA) (between 27 degrees S and 40 degrees S) is bordered to the west by the convergent margin between the continental South American Plate and the oceanic Nazca Plate. The subduction angle along this margin is variable, as is the deformation of the upper plate. Between 33 degrees S and 35 degrees S, the subduction angle of the Nazca plate increases from sub-horizontal (< 5 degrees) in the north to relatively steep (similar to 30 degrees) in the south. The SCA contain inherited lithological and structural heterogeneities within the crust that have been reactivated and overprinted since the onset of subduction and associated Cenozoic deformation within the Andean orogen. The distribution of the deformation within the SCA has often been attributed to the variations in the subduction angle and the reactivation of these inherited heterogeneities. However, the possible influence that the thickness and composition of the continental crust have had on both short-term and long-term deformation of the SCA is yet to be thoroughly investigated. For our investigations, we have derived density distributions and thicknesses for various layers that make up the lithosphere and evaluated their relationships with tectonic events that occurred over the history of the Andean orogeny and, in particular, investigated the short- and long-term nature of the present-day deformation processes. We established a 3D model of lithosphere beneath the orogen and its foreland (29 degrees S-39 degrees S) that is consistent with currently available geological and geophysical data, including the gravity data. The modelled crustal configuration and density distribution reveal spatial relationships with different tectonic domains: the crystalline crust in the orogen (the magmatic arc and the main orogenic wedge) is thicker (similar to 55 km) and less dense (similar to 2900 kg/m(3)) than in the forearc (similar to 35 km, similar to 2975 kg/m(3)) and foreland (similar to 30 km, similar to 3000 kg/m(3)). Crustal thickening in the orogen probably occurred as a result of stacking of low-density domains, while density and thickness variations beneath the forearc and foreland most likely reflect differences in the tectonic evolution of each area following crustal accretion. No clear spatial relationship exists between the density distribution within the lithosphere and previously proposed boundaries of crustal terranes accreted during the early Paleozoic. Areas with ongoing deformation show a spatial correlation with those areas that have the highest topographic gradients and where there are abrupt changes in the average crustal-density contrast. This suggests that the short-term deformation within the interior of the Andean orogen and its foreland is fundamentally influenced by the crustal composition and the relative thickness of different crustal layers. A thicker, denser, and potentially stronger lithosphere beneath the northern part of the SCA foreland is interpreted to have favoured a strong coupling between the Nazca and South American plates, facilitating the development of a sub-horizontal slab. KW - Central andes KW - Lithospheric structure KW - Crustal density KW - Gravity KW - modelling KW - Subduction Y1 - 2020 U6 - https://doi.org/10.1007/s00531-020-01962-1 SN - 1437-3254 SN - 1437-3262 VL - 110 IS - 7 SP - 2333 EP - 2359 PB - Springer CY - New York ER - TY - JOUR A1 - Rodriguez Piceda, Constanza A1 - Scheck-Wenderoth, Magdalena A1 - Cacace, Mauro A1 - Bott, Judith A1 - Strecker, Manfred T1 - Long-Term Lithospheric Strength and Upper-Plate Seismicity in the Southern Central Andes, 29 degrees-39 degrees S JF - Geochemistry, geophysics, geosystems N2 - We examined the relationship between the mechanical strength of the lithosphere and the distribution of seismicity within the overriding continental plate of the southern Central Andes (SCA, 29 degrees-39 degrees S), where the oceanic Nazca Plate changes its subduction angle between 33 degrees S and 35 degrees S, from subhorizontal in the north (<5 degrees) to steep in the south (similar to 30 degrees). We computed the long-term lithospheric strength based on an existing 3D model describing variations in thickness, density, and temperature of the main geological units forming the lithosphere of the SCA and adjacent forearc and foreland regions. The comparison between our results and seismicity within the overriding plate (upper-plate seismicity) shows that most of the events occur within the modeled brittle domain of the lithosphere. The depth where the deformation mode switches from brittle frictional to thermally activated ductile creep provides a conservative lower bound to the seismogenic zone in the overriding plate of the study area. We also found that the majority of upper-plate earthquakes occurs within the realm of first-order contrasts in integrated strength (12.7-13.3 log Pam in the Andean orogen vs. 13.5-13.9 log Pam in the forearc and the foreland). Specific conditions characterize the mechanically strong northern foreland of the Andes, where seismicity is likely explained by the effects of slab steepening. KW - subduction zone KW - Andes KW - rheology KW - seismicity KW - flat-slab Y1 - 2022 U6 - https://doi.org/10.1029/2021GC010171 SN - 1525-2027 VL - 23 IS - 3 PB - American Geophysical Union CY - Washington ER -