Pleistocene pedogenic carbonates from alluvial paleosols in eastern Sudan reveal a semi-arid and seasonal climate, similar to today

作者：M. Mohammednoor, Faysal Bibi, Ulrich Struck, Ali Eisawi, Robert Bussert · 发表于：CATENA · 年份：2024 · DOI：10.1016/j.catena.2024.108583 · 被引用次数：5 · 研究领域：Pleistocene-Era Hominins and Archaeology、Geology and Paleoclimatology Research、Evolution and Paleontology Studies

• Pleistocene pedogenic carbonates in eastern Sudan are mainly calcretes and nodules. • An initially semi-arid climate that became more humid and then semi-arid again. • A mixture of C 3 and C 4 vegetation cover was present. • Mean annual precipitation was likely greater than 350 mm/yr and similar to today. • Calcretes formed in floodplains in a climate similar to that in East Africa. Pedogenic carbonates can provide important information regarding paleoclimatic conditions. Compared with East Africa, Pleistocene pedogenic carbonates in Sudan, particularly calcretes, have received very little attention, particularly with regard to local paleoclimatic reconstructions. Pleistocene alluvial sediments aged from ∼230 to <17 ka were deposited along the middle Atbara River in eastern Sudan. Intercalated in these alluvial deposits are paleosols in which different types of pedogenic carbonates occur. Petrographic, mineralogical and isotopic analyses were performed to reconstruct the regional paleoenvironmental conditions. The investigated pedogenic carbonates are appropriate for paleoclimatic reconstruction because they are free of inherited carbonate and diagenetic modification. The paleosols identified in a previous study as Aridisols/Calcisols contain calcrete horizons that consist of an orthic nodular horizon, sometimes overlain by a laminar horizon. Paleosols identified as Vertisols contain slickensides, and disorthic and septaric nodules. The paleosols show stable carbon and oxyg...