@article{NeuharthBruneWronaetal.2022, author = {Neuharth, Derek and Brune, Sascha and Wrona, Thilo and Glerum, Anne and Braun, Jean and Yuan, Xiaoping}, title = {Evolution of rift systems and their fault networks in response to surface processes}, series = {Tectonics}, volume = {41}, journal = {Tectonics}, number = {3}, publisher = {American Geophysical Union}, address = {Washington}, issn = {0278-7407}, doi = {10.1029/2021TC007166}, pages = {22}, year = {2022}, abstract = {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.}, language = {en} } @article{NeuharthBruneGlerumetal.2021, author = {Neuharth, Derek and Brune, Sascha and Glerum, Anne and Morley, Chris K. and Yuan, Xiaoping and Braun, Jean}, title = {Flexural strike-slip basins}, series = {Geology : a venture in earth science reporting / the Geological Society of America}, volume = {50}, journal = {Geology : a venture in earth science reporting / the Geological Society of America}, number = {3}, publisher = {American Institute of Physics}, address = {Boulder}, issn = {0091-7613}, doi = {10.1130/G49351.1}, pages = {361 -- 365}, year = {2021}, abstract = {Strike-slip faults are classically associated with pull-apart basins where continental crust is thinned between two laterally offset fault segments. We propose a subsidence mechanism to explain the formation of a new type of basin where no substantial segment offset or synstrike-slip thinning is observed. Such "flexural strike-slip basins" form due to a sediment load creating accommodation space by bending the lithosphere. We use a two-way coupling between the geodynamic code ASPECT and surface-processes code FastScape to show that flexural strike-slip basins emerge if sediment is deposited on thin lithosphere close to a strike slip fault. These conditions were met at the Andaman Basin Central fault (Andaman Sea, Indian Ocean), where seismic reflection data provide evidence of a laterally extensive flexural basin with a depocenter located parallel to the strike-slip fault trace.}, language = {en} } @article{RichterBruneRiedletal.2021, author = {Richter, Maximilian and Brune, Sascha and Riedl, Simon and Glerum, Anne and Neuharth, Derek and Strecker, Manfred}, title = {Controls on asymmetric rift dynamics}, series = {Tectonics / American Geophysical Union, AGU ; European Geophysical Society, EGS}, volume = {40}, journal = {Tectonics / American Geophysical Union, AGU ; European Geophysical Society, EGS}, number = {5}, publisher = {American Geophysical Union}, address = {Washington}, issn = {0278-7407}, doi = {10.1029/2020TC006553}, pages = {21}, year = {2021}, abstract = {Complex, time-dependent, and asymmetric rift geometries are observed throughout the East African Rift System (EARS) and are well documented, for instance, in the Kenya Rift. To unravel asymmetric rifting processes in this region, we conduct 2D geodynamic models. We use the finite element software ASPECT employing visco-plastic rheologies, mesh-refinement, distributed random noise seeding, and a free surface. In contrast to many previous numerical modeling studies that aimed at understanding final rifted margin symmetry, we explicitly focus on initial rifting stages to assess geodynamic controls on strain localization and fault evolution. We thereby link to geological and geophysical observations from the Southern and Central Kenya Rift. Our models suggest a three-stage early rift evolution that dynamically bridges previously inferred fault-configuration phases of the eastern EARS branch: (1) accommodation of initial strain localization by a single border fault and flexure of the hanging-wall crust, (2) faulting in the hanging-wall and increasing upper-crustal faulting in the rift-basin center, and (3) loss of pronounced early stage asymmetry prior to basinward localization of deformation. This evolution may provide a template for understanding early extensional faulting in other branches of the East African Rift and in asymmetric rifts worldwide. By modifying the initial random noise distribution that approximates small-scale tectonic inheritance, we show that a spectrum of first-order fault configurations with variable symmetry can be produced in models with an otherwise identical setup. This approach sheds new light on along-strike rift variability controls in active asymmetric rifts and proximal rifted margins.}, language = {en} }