TY  - JOUR
A1  - Richter, Maximilian
A1  - Brune, Sascha
A1  - Riedl, Simon
A1  - Glerum, Anne
A1  - Neuharth, Derek
A1  - Strecker, Manfred
T1  - Controls on asymmetric rift dynamics
BT  - Numerical modeling of strain localization and fault evolution in the Kenya Rift
JF  - Tectonics / American Geophysical Union, AGU ; European Geophysical Society, EGS
N2  - 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.
KW  - asymmetric rifting
KW  - rift variability
KW  - numerical model
KW  - structural
KW  - inheritance
KW  - Kenya Rift
Y1  - 2021
U6  - https://doi.org/10.1029/2020TC006553
SN  - 0278-7407
SN  - 1944-9194
VL  - 40
IS  - 5
PB  - American Geophysical Union
CY  - Washington
ER  -