Paleogeography and stratigraphy of Cretaceous coal deposits of North Africa

Abstract

The Cretaceous coal-bearing facies of North and West Africa are directly related to the breakup of Africa and North and South America, global sea-level fluctuations, and the resulting marine transgressive and regressive cycles. In the Cretaceous, the coals of North Africa formed near the equator in a warm and humid climate, in contrast to the North American temperate coals. Lower Cretaceous coal-bearing facies have been reported in North Africa in Algeria, Egypt, Ethiopia, Libya, Mauritania, and Senegal. Upper Cretaceous coal has been reported in Benin, Egypt, Mali, Niger, Nigeria, Senegal, and Sudan. A better understanding of Cretaceous facies relationships and shoreline trends should lead to the discovery of more coal deposits within North Africa. Major marine transgressions and regressions associated with rifting, the breakup of Gondwana and Laurasia, and eustatic sea level cycles developed during Cretaceous time in North and West Africa. During the Mesozoic Era, most of Africa was above sea level and marine deposition took place only in the marginal basins associated with the rifting of the continents. The opening of the South Atlantic and the breakup of Africa and south America occurred along a north-south rift system that began in the south during the latest Jurassic and migrated northward in the Early Cretaceous, reaching Nigeria by mid-Cretaceous time. The first marine connection between the North and South Atlantic occurred during late Albian time. Final separation of the continents occurred during the Santonian, and the permanent seaway developed in early Turanian time. The Tethys sea advanced across the Saharan Platform during the late Cenomanian-Turonian, Coniacian, late Campanian-Maastrichtian, and the Paleocene. Concurrently, the South Atlantic transgressed through the Benue Trough and Nupe Basin and linked with the Tethys sea in the Chad and lullemmeden Basins, forming the four trans-Saharan epeiric seaways.

Metalliferous Coals of Cretaceous Age: A Review

“…Coal-bearing strata typically occur in Permian aged deposits in the southern half of Africa, and deposits of Triassic, Cretaceous, and Miocene age are documented in the northern half of the continent (Figure 20; refer to https: //pubs.er.usgs.gov/publication/ofr20081258 (accessed 6 September 2022) for the Google Earth map). Of the Cretaceous coal-bearing sedimentary successions, those from Nigeria are best documented, although deposits have also been reported from Algeria, Benin, Egypt, Libya, Mali, Mauritania, Niger, Senegal, and Sudan [138,139]. The Cretaceous coal-bearing facies of North Africa formed in a warm to humid climate and experienced major marine transgressions and regressions of the Tethys Sea, associated with the break-up of Gondwana and Laurasia, the initial opening of the Atlantic Ocean, and formation of the Equatorial Atlantic Magmatic Province [140,141].…”

“…The Cretaceous coal-bearing facies of North Africa formed in a warm to humid climate and experienced major marine transgressions and regressions of the Tethys Sea, associated with the break-up of Gondwana and Laurasia, the initial opening of the Atlantic Ocean, and formation of the Equatorial Atlantic Magmatic Province [140,141]. The Lower Cretaceous coal facies formed along the Tethys shoreline in the northern parts of North Africa and appear absent in the southern North African basins, although local fluvial deposits may occur in these regions [138]. In the Late Cretaceous, as the Tethys Sea experienced a southward transgression and Atlantic waters moved northwards linking to the Tethys Sea, coal facies developed along the epicontinental seaways and coastal plains across North Africa [138].…”

“…The Lower Cretaceous coal facies formed along the Tethys shoreline in the northern parts of North Africa and appear absent in the southern North African basins, although local fluvial deposits may occur in these regions [138]. In the Late Cretaceous, as the Tethys Sea experienced a southward transgression and Atlantic waters moved northwards linking to the Tethys Sea, coal facies developed along the epicontinental seaways and coastal plains across North Africa [138]. The Nigerian Cretaceous-aged coal deposits are lignitic to sub-bituminous to bituminous in rank [143,144], and the coal seams are usually interbedded with bands of shales and mudstones, some of which are oil-bearing.…”

“…12, x FOR PEER REVIEW 30 of 53 transgression and Atlantic waters moved northwards linking to the Tethys Sea, coal facies developed along the epicontinental seaways and coastal plains across North Africa[138].…”