Entstehung und archäologische Bedeutung oolithischer Eisenerze im Suda. Formation and archaeological significance of oolitic ironstones in Sudan

The Kingdom of Kush, located in modern-day Sudan, is famed for its ‘black pharaoes’. Less familiar to most is that at its last capital, the Royal City of Meroe, listed by UNESCO as a world heritage cultural site, iron was produced at large scale for more than 1,000 years, starting at least by the 7th century BC (Humphris & Scheibner 2017). The location of the iron ore mines and the lithotype of the extracted iron ore that was used for the iron smelting have remained obscure. Ongoing research under the leadership of the University College London Qatar (UCL Qatar) has resulted in the discovery of up to 20 separate mining areas and several hundred individual mining sites (see Humphris et al. forthcoming for archaeological details). The surface mines are located east of Meroe and up to 9 km away from the Nile on top of plateaux and buttes that consist of Late Cretaceous siliciclastic sediments. Several types of sedimentary iron accumulations occur. During id signifi cant iron bloom. The oolitic ironstones areoolitic wacke- to pack-ironstones that are made of ooids and less peloids in a matrix of ironoxides. Mineralogically they consisron smelting experiments (Charlton & Humphris 2017), only the most iron-rich of the local iron ores, the oolitic ironstones, producet of goethite and minor hematite. They form up to three separate lenses or discontinuous beds at a maximum of 40 cm in thickness on top of lateritic weathering profiles. The matrix-supported or matrix-rich massive fabric, gradual contacts of the oolitic ironstones to ferricretes, abundant root traces, broken and ductile deformed ooids as well as a gradual transition from iron microconcretions to peloids to ooids suggest that the ooids originated mainly in situ. The fi ndings indicate that the oolitic ironstones formed by lateritic weathering processes following the deposition of the sediments, most likely during the Paleogene