Earthquake data collected from regional and international seismological stations was compiled in order to produce a seismicity map for the Sudan and South Sudan. The seismicity and tectonic information were used to identify the relationship between the distribution of earthquakes and active geological structures and further to create seismic source zones. The results showed that the study area lies within seismically-active region which can be divided into three major seismic source zones, namely the Southern Seismic Source Zone (SSSZ; Ms=7.2 ), the Northeastern Seismic Source Zone (NSSZ; mb=5.9 ), the Central Seismic Source Zone (CSSZ; Ms=5.5 ). The SSSZ is bounded by latitudes 3o00 and 10°00 N and longitudes 22o00 and 36°00 E. The seismic activity associated with this zone is attributed to the extension of the western branch of the East African Rift System into South Sudan, or possibly related to rejuvenation of movement in the fault-bounded basins of South Sudan. The NSSZ is located to the west of the presently active seismicity along the Red Sea trough. The third zone seismicity is possibly related to rejuvenation of movement along the Central African Shear Zone (CASZ). Additional minor seismic activity is probably related to Cenozoic volcanicity in Jebel Merra and Bayuda volcanic fields.
Based on field investigation of twenty eight vertical and lateral sedimentary profiles in the Gedaref area, nine sedimentary facies have been identified based on lithofacies analysis. The identified sedimentary facies are named: matrix-supported massive conglomerate (Gmm), trough cross-bedded sandstone (St), planner cross-bedded sandstone (Sp), ripple cross-lamination sandstone (Sr), horizontal-bedded sandstone (Sh), massive sandstone (Sm), laminated sandstone and mudstone (Fl), massive mudstone (Fsm) and paleosol (P). These facies are grouped into three sedimentary facies associations: FA1consists: Sp, Sm, Sh ± (Fsm, St, P and Fl) representing sandy fluvial channel; FA 2 include: Sm, Gmm, St ± (Fsm and Sh) representing sandy point bars and FA 3 consists: Fsm, Fl ± (St and Sh) representing lake deposits. These associations indicate that the studied sediments have been deposited under fluvial conditions (multi braided and meandering channels) in Wad Hari and Rumeila respectively, shifted into lacustrine settings at Magareef and Rashed areas towards the basin center. Paleo-current data indicate that the source area was located southeast of the study area.
This paper presents for the first time, palynological results from the subsurface part of the Shendi Formation, in central Sudan. The study is based on eight samples of grey mudstones collected from three shallow water wells penetrated the Shendi Formation. Standard palynological preparation technique, which involves inorganic acids was used to extract the organic matter from the enclosed sediments. The recovered material is characterized by well preserved and fairly diversified miospores in which angiosperm pollen form the major constituent; gymnosperms and bryophyte/ptridophyte spores are relatively fewer. The coexistence of marker species such as Monocolpopollenites spheroidites Zlivisporis blanensis, Longapertites sp. 3, Proteacidites sigalii, Echitriporites trianguliformis, Syncolporites schrankii, Retidiporites magdalenensis indicates a Campanian-Maastrichtian age for the subsurface part of the Shendi Formation. The palynomorph assemblage encountered herein, is characteristic of the Senonian Palmae province.
This study examines both vertical and lateral facies changes as well as petrographic characteristics of the outcropping section of the Upper Cretaceous Shendi Formation in the Musawwarat-Naga area with a view of interpreting the depositional environment, provenance, and tectonic setting that prevailed during the deposition of the sediments. Field studies revealed the presence of eight different sedimentary lithofacies. The predominant is the trough cross-bedded sandstone facies (St), representing 75% of the total succession. Four architectural elements were recognized: sandy bedforms (SB), channel fill (CH), gravelly bars and bedforms (GB), and overbank fines (OF). Moreover, the mean value of paleocurrent directions was 285.3°, suggesting a southeasterly located source area. The majority of the sandstones were classified as quartz arenites with subordinate sublithic-arenites. Ternary plots of quartz-feldspar-lithic fragments (QFL) revealed that the tectonic setting is predominantly within the interior craton. It can be suggested that the sediments were sourced from the southeast region and associated with a braided, proximal, fluvial depositional environment. The results of this study provide outcrop analog data that might be useful in exploring hydrocarbons. Specifically, it can enhance the understanding and prediction of the proximal fluvial depositional styles in the subsurface deposits in the Shendi-Atbara Basin and similar rift basins in Sudan and Africa.
Abstract The palynology of the Upper Cretaceous to Neogene non-marine succession in the Melut Basin, southeast Sudan was investigated. The palynomorphs are overwhelmingly of terrestrial origin, but rare brackish water dinoflagellate cysts and scolecodonts were encountered from the Lower Miocene and Oligocene-Miocene. Mangrove pollen, which is common in coeval West African coastal basins, is rare and inconsistent. Examples are Spinizonocolpites (Nypa) from the Campanian-Maastrichtian to Eocene and Rhizophoraceae (Zonocostites ramonae) from the Neogene. Based on the stratigraphic distribution of selected pollen and spores from four exploration wells, eight informal palynozones from the Campanian to the Neogene are proposed. The zones, in stratigraphically ascending order, are as follows: Assemblage Zone I, Campanian (lower Melut Formation); Assemblage Zone II, Campanian-Maastrichtian (middle Melut Formation); Assemblage Zone III, Maastrichtian (upper Melut Formation); Assemblage Zone IV, Paleocene (Yale For...
