3D Thermo-mechanical Model of Lithospheric Buoyancy-Driven Extension of the East African Rift
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Description: This contribution is provided to complement the manuscript published in 2021 in Geophysical Research Letters by these authors. The paper is entitled Role of Lithospheric Buoyancy Forces in Driving Deformation in East Africa from 3D Geodynamic Modeling. Here we provide our 3D thermo-mechanical model of lithospheric buoyancy-driven extension of the East African Rift and surroundings. The 3D thermo-mechanical model was simulated using the open source code ASPECT. The aim of this work is to investigate what forces drive continental rifting in East Africa and surroundings. We investigate rifting along the East African Rift (EAR), which is the largest continental rift on Earth. Some studies suggest relatively shallow forces, known as lithospheric buoyancy forces, dominate the rifting. However, others suggest that deeper forces arising from interactions with mantle flow are driving the extension in the EAR. Here, we use the code ASPECT to perform realistic 3D simulations to estimate the contribution of lithospheric buoyancy forces in driving the EAR. We find that lithospheric buoyancy forces are the primary driver of ~E-W rigid block motion across the EAR, whereas the deeper forces may be driving rift-parallel motions along the boundaries of rigid blocks. This result provides new insight into our understanding of how continents break-up. Lithospheric buoyancy forces are implemented using the ETOPO1 topography dataset, CRUST1.0 for crustal thicknesses and densities, and the model is isostatically compensated at 100 km. The model provided is contained in the directory (East_African_Rift_Lithospheric_Buoyancy_Driven_Extension_3D_Model), which includes files that allow for visualization in 3D using the software VISIT or PARAVIEW. Visualization parameters include: temperature field, viscosity, density, topography, pressure, compositional fields, mesh, velocities, and strain rate. We also provide the data file of our modeling outputs and inputs that are described as follow: The model outputs are in the following files: 1. East_African_Rift_Lithospheric_Buoyancy_Driven_Extension_3D_Model.csv Contains the same model as in the directory "East_African_Rift_Lithospheric_Buoyancy_Driven_Extension_3D_Model" but in .csv format, which can be used to extract information from the model and plot in another software such as Generic Mapping Tools (GMT). 2. model1_GPE.csv Gravitational Potential Energy (GPE) calculated by vertically integrating lithostatic pressure, derived form CRUST1.0 and ETOPO1, from the surface to 100 km depth formatted as: longitude [o], latitude [o], and GPE [TN/m] . 3. model2_dynamic_strain_rate.csv Calculated dynamic strain rate at the deforming zones formatted as: longitude [o], latitude [o], strain rate [1e-8/yr]. 4. model3_rigid_block_dynamic_velocity.csv Calculated dynamic velocities of the Somalian Plate, and for Victoria and Rovuma Blocks formatted as: longitude [o], latitude [o], East velocity [mm/yr], North velocity [mm/yr]. 5. model4_GPS_dynamic_velocity.csv Calculated dynamic velocities at GPS locations within the deforming zones of the East African Rift formatted as: longitude [o], latitude [o], East velocity [mm/yr], North velocity [mm/yr]. 6. model5_inputs_topography_layers_thickness_density.csv Model inputs for the 3D model lithospheric deformation model including formatted as: longitude [o], latitude [o], topography [m], base of upper crust [m], base of middle crust [m], base of lower crust [m], synthetic lithosphere thickness [m], upper crust density [kg/m3], middle crust density [kg/m3], lower crust density [kg/m3], compensated mantle lithosphere density [kg/m3].