TY - JOUR A1 - Neuharth, Derek A1 - Brune, Sascha A1 - Wrona, Thilo A1 - Glerum, Anne A1 - Braun, Jean A1 - Yuan, Xiaoping T1 - Evolution of rift systems and their fault networks in response to surface processes JF - Tectonics N2 - Continental rifting is responsible for the generation of major sedimentary basins, both during rift inception and during the formation of rifted continental margins. Geophysical and field studies revealed that rifts feature complex networks of normal faults but the factors controlling fault network properties and their evolution are still matter of debate. Here, we employ high-resolution 2D geodynamic models (ASPECT) including two-way coupling to a surface processes (SP) code (FastScape) to conduct 12 models of major rift types that are exposed to various degrees of erosion and sedimentation. We further present a novel quantitative fault analysis toolbox (Fatbox), which allows us to isolate fault growth patterns, the number of faults, and their length and displacement throughout rift history. Our analysis reveals that rift fault networks may evolve through five major phases: (a) distributed deformation and coalescence, (b) fault system growth, (c) fault system decline and basinward localization, (d) rift migration, and (e) breakup. These phases can be correlated to distinct rifted margin domains. Models of asymmetric rifting suggest rift migration is facilitated through both ductile and brittle deformation within a weak exhumation channel that rotates subhorizontally and remains active at low angles. In sedimentation-starved settings, this channel satisfies the conditions for serpentinization. We find that SP are not only able to enhance strain localization and to increase fault longevity but that they also reduce the total length of the fault system, prolong rift phases and delay continental breakup. KW - rifts KW - fault network KW - surface processes KW - geodynamics Y1 - 2022 U6 - https://doi.org/10.1029/2021TC007166 SN - 0278-7407 SN - 1944-9194 VL - 41 IS - 3 PB - American Geophysical Union CY - Washington 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 -