207-11 The Zalingei Fold Belt, Darfur, Sudan: A test of cratonic stability

Session: Honoring the Late Professor Mohamed Abdelsalam: Outstanding Researcher, Generous Colleague, Legendary Mentor, and Ambassador for the Geosciences In Africa

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Cratons are interpreted as regions of ancient continental crust that have remained stable for billions of years. In 2002, Abdelsalam et al. hypothesized that in some cases, cratonic crust could be remobilized within crustal belts that have undergone tectonic deformation but have been tectonically quiescent long enough to appear stable. In northeastern Africa, they interpreted the Saharan Metacraton (SMc) in this framework, and much work in the region since then has followed this paradigm. More recently, de Wit et al. (2021) proposed an alternative hypothesis that the SMc and other cratons in Africa are composed of shields accreted along collisional mobile belts. The Zalingei Fold Belt (ZFB) in Darfur, Sudan, provides a natural laboratory to assess these hypotheses. Between 2020 and 2021, we mapped and sampled three primary lithological groups within the ZFB, including gneisses, schists, and granitoids. All the samples are being analyzed with zircon U-Pb, Lu-Hf, and (U-Th)/He geochronology, white mica Ar-Ar geochronology, and major and trace-element geochemistry to determine which, if any, of the aforementioned hypotheses are supported in this region of Africa. Field mapping shows evidence of E-W trending, double-plunging folds, and what appears to be multiple generations of foliations. Geochemical results from the layered gneisses, schists, and granitoids show somewhat negative Europium (Eu) anomalies. In the magmatic rocks, this negative anomaly indicates a deficiency in plagioclase, which happens due to the early separation of plagioclase from the melt before the crystallization of the rock. These rare earth element signatures suggest a juvenile origin of the crust. Both foliated and unfoliated granitoids are chemically homogenous with less Ti, Fe, and Mg compared to Ca, K, Al, and Na. Trends from the granitoid samples, which show relative enrichment in incompatible light rare earth elements (LREE) and strong depletion in compatible heavy rare earth elements (HREE), indicate that the granitoids likely formed in a collisional zone. These preliminary results suggest that the ZFB is part of a zone of juvenile Neoproterozoic(?)crust, extending SW-NE through both the Jebel Rahib suture and the Atmur-Delgo suture, in support the theory of de Wit et al 2021.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

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