epc_Rui_Stamps_JGR_2022

Machine learning Matlab code with example input to accompany a publication by Rui and Stamps (2022) JGR

3D Thermo-mechanical Model of Lithospheric Buoyancy-Driven Extension of the East African Rift

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]

Density structure beneath the Rungwe volcanic province and surroundings, East Africa from shear-wave velocity perturbations constrained inversion of gravity data

Density perturbations in the subsurface are the main driver of mantle convection and can contribute to lithospheric deformation. However, in many places the density structure in the subsurface is poorly constrained. Most geodynamic models rely on simplified equations of state or use linear seismic velocity perturbations to density conversions. In this study, we investigate the density structure beneath the Rungwe Volcanic Province (RVP), which is the southernmost volcanic center in the Western Branch of the East African Rift (EAR). We use shear-wave velocity perturbations ((Formula presented.)) as a reference model to perform constrained inversions of satellite gravity data centered on the RVP. We use the code jif3D with a (Formula presented.) -density coupling criterion based on mutual information to generate a 3D density model beneath the RVP up to a depth of 660 km. Our results reveal a conspicuous negative density anomaly (∼−200 kg/m3) in the sublithospheric mantle (at depths ranging from ∼100 km to ∼250 km) beneath the central part of the Malawi Rift extending to the west, beneath the Niassa Craton, coincident with locations with positive shear-wave velocity perturbations (+7%). We calculate a 3D model of the velocity-to-density conversion factor (f) and find negative f-values beneath the Niassa Craton which suggests the observed negative density anomaly is mostly due to compositional variations. Apart from the Niassa Craton, there are generally positive f-values in the study area, which suggest dominance of temperature control on the density structure. Although the RVP generally shows negative density anomalies and positive f-values, at shallow depths (<120 km), f (Formula presented.) 0, which suggests important contributions of both temperature and composition on the density structure possibly due to the presence of plume material. The negative buoyancy of the Niassa Craton contributes to its long stability, while constituting a barrier to the southward flow of plume material, thus restricting the southward continuation of magmatism in the Western Branch of the EAR. The presence of a negative-density anomaly where (Formula presented.) are positive is incompatible with models based on the use of simple (Formula presented.) to density conversion factors. These results have implications on how (Formula presented.) models are converted to density perturbations

The Historic Scotland guide to international conservation charters

SIGLEAvailable from British Library Document Supply Centre-DSC:4316.0848(8) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Supplementary files for Vertical Displacements and Sea-Level Changes in Eastern North America Driven by Glacial Isostatic Adjustment: an Ensemble Modeling Approach

<p>Model input and output files associated with the manuscript entitled "Vertical Displacements and Sea-Level Changes in Eastern North America Driven by Glacial Isostatic Adjustment: an Ensemble Modeling Approach" that will be submitted to Journal of Geophysical Research.</p>This material is based upon work supported by the U.S. Geological Survey under Grant/Cooperative Agreement No. G21AC10016. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the opinions or policies of the U.S. Geological Survey. Mention of trade names or commercial products does not constitute their endorsement by the U.S. Geological Survey. This work is also supported by the National Science Foundation under grant number 1735139. SELEN is hosted by the Computational Infrastructure for Geodynamics (CIG) which is supported by the National Science Foundation awards NSF-0949446, NSF-1550901, and NSF-2149126

Lithospheric Control of Melt Generation Beneath the Rungwe Volcanic Province, East Africa: Implications for a Plume Source

This contribution is provided to complement the manuscript published in 2021 in Journal of Geophysical Research: Solid Earth by these authors. The paper is entitled Lithospheric Control of Melt Generation Beneath the Rungwe Volcanic Province, East Africa: Implications for a Plume Source Here we provide our 3D lithospheric-modulated convection model that incorporates melt generation beneath the Rungwe Volcanic Province (RVP), a volcanic center in the magma-poor Western Branch of the East African Rift. The 3D LMC was simulated using the open source code ASPECT version 2.2.0-pre. The aim of this work is to investigate the source of sublithospheric melt beneath the RVP. We test the hypothesis that sublithospheric melt feeding the RVP can be generated from LMC. We develop a 3D thermomechanical model of LMC beneath the RVP and the Malawi Rift and constrain parameters for sublithospheric melt generation due to LMC. We assume a rigid lithosphere and use non-Newtonian, temperature-, pressure- and porosity-dependent creep laws of anhydrous peridotite for the sublithospheric mantle. We find a pattern of upwelling from LMC beneath the RVP. The upwelling generates melt only for elevated mantle potential temperatures (Tp), which suggests a heat source possibly from plume material. At elevated Tp, LMC associated decompression melt occurs at a maximum depth of ~150 km beneath the RVP. We suggest upwelling due to LMC entrains plume materials resulting in melt generation beneath the RVP. The models provided are contained in the following directories : 1. njinju_et_al_2021_JGR_1800K_normal_litho 2. njinju_et_al_2021_JGR_1800K_litho_minus10 3. njinju_et_al_2021_JGR_1800K_litho_plus10 4. njinju_et_al_2021_JGR_1723K_normal_litho These directories are respectively models of LMC for a mantle potential temperature of 1800 K and: (1) a normal lithospheric thickness (updated Fishwick, 2010); (2) the normal lithospheric thickness minus 10 km; (3) the normal lithospheric thickness plus 10 km and (4) models of LMC for a mantle potential temperature of 1723 K and a normal lithospheric thickness. The above models (directories) include files that allow for visualization in 3D using the software VISIT or PARAVIEW. Visualization parameters include: temperature field, viscosity, density, pressure, compositional fields, mesh, and velocities. We also provide the csv files of our modeling outputs and inputs that are described as follow: The outputs of the model "njinju_et_al_2021_JGR_1800K_normal_litho" are extracted in csv format at 10 Ma, 17 Ma and 20 Ma timesteps as in the following files: a. njinju_et_al_2021_JGR_1800K_normal_litho_10Ma.csv b. njinju_et_al_2021_JGR_1800K_normal_litho_17Ma.csv c. njinju_et_al_2021_JGR_1800K_normal_litho_20Ma.csv Each of these csv files contain 16 columns with the following names: "velocity:0","velocity:1","velocity:2","p","T","crust","mantle_lithosphere","porosity","peridotite","density","viscosity","melt_fraction","nonadiabatic_temperature","Points:0","Points:1","Points:2". These csv files can be used to extract information from the model and plot in another software such as Generic Mapping Tools (GMT)

Victoria continental microplate dynamics controlled by the lithospheric strength distribution of the East African Rift

One of the largest continental microplates on Earth is situated in the center of the East African Rift System, and oddly, the Victoria microplate rotates counterclockwise with respect to the neighboring African tectonic plate. Here, the authors' modelling results suggest that Victoria microplate rotation is caused by edge-driven lithospheric processes related to the specific geometry of rheologically weak and strong regions