Gravity Evidence for a Larger Limpopo Belt in Southern Africa and Geodynamic Implications

The Limpopo Belt of southern Africa is a Neoarchean orogenic belt located between two older Archean provinces, the Zimbabwe craton to the north and the Kaapvaal craton to the south. Previous studies considered the Limpopo Belt to be a linearly trending east-northeast belt with a width of ∼250 km and ∼600 km long. We provide evidence from gravity data constrained by seismic and geochronologic data suggesting that the Limpopo Belt is much larger than previously assumed and includes the Shashe Belt in Botswana, thus defining a southward convex orogenic arc sandwiched between the two cratons. The 2 Ga Magondi orogenic belt truncates the Limpopo-Shahse Belt to the west. The northern marginal, central and southern marginal tectonic zones define a single gravity anomaly on upward continued maps, indicating that they had the same exhumation history. This interpretation requires a tectonic model involving convergence between the Kaapvaal and Zimbabwe cratons during a Neoarchean orogeny that preserved the thick cratonic keel that has been imaged in tomographic models

Geotechnical investigation of soil properties in Hatsalatladi village, Botswana; Insights from aeromagnetic, laboratory soil tests and Rayleigh wave dispersion datasets

Soil tests and Multichannel Analysis of Surface Waves (MASW) data were conducted in Hatsalatladi village, Botswana, to investigate the occurrence of ground fissures within the village and to identify the likely causes of the fissures and their depth extent. The MASW data were collected to gain insights into the variation of shear wave velocity with depth. The dataset shows that the shear wave velocity ranged from 150 m/s – 500 m/s, with Poisson's ratios ranging from 0.02 to 0.25. A low-velocity zone (LVZ) was observed in the upper 5 m of the subsurface with velocities ranging from 200 m/s to 350 m/s.The soil plasticity was measured through the plastic and liquid Atterberg tests. Atterberg limits measurements obtained from the three survey sites show that the plastic index of the soil samples collected from depths of 1 m fall within the 10–20% range. Specifically, the Filled Crack survey site had a plastic index of 16%, while the Abandoned House and Bridge sites had 18.7% and 13.5%, respectively. Soil samples from Filled Crack and Abandoned House site revealed a linear shrinkage of 6.4%, while the Bridge site soil sample had a linear shrinkage of 2.9%. The sieve analysis test results are also presented