Structure of the South Sudan rift basins based on gravity and magnetic studies

摘要

The southern Sudan rift basins form part of the Mesozoic Central African Rift System (CARS) and span an area 1000 km wide and 800 km along strike. They consist of two major NW-SE trending rift basins; the Muglad and the Melut. Following a series of gravity, magnetic and seismic related studies (Fairhead et al., 2012) most of the rift system's kinematics and structural evolution are reasonably well understood.. However, ambiguities exist, where these rift basins coalesce towards the Kenyan border and the structural continuation and linkage to the Anza Rift (figure 1). This partly relates to a data gap across political borders. This study (King, 2012) utilised the 5' (~10km) and 1km grids of gravity and magnetic data from Getech's African Gravity Project (AGP) and African Magnetic Mapping Project (AMMP). The ground gravity station distribution is shown as red dots and the aeromagnetic surveys are shown by the blue polygons in Figure 2. The regional rift basin setting is given by Figure 1 and shows the uncertain relation between the South Sudan rift basins and the Anza rift basin in Kenya. These data sets were interpreted using a range of techniques to provide an integrated robust regional interpretation that reveals insights into the rift evolution of South Sudan and northern Kenya. The principal findings are evidence for an E-W trending shear zone linking the South Sudan basins to the Anza Rift, and the identification of a discrete N-S oriented basin related to a small shear zone in South Sudan.