Paleoclimate and paleoenvironment reconstruction of paleosols spanning the Lower to Upper Cretaceous from the Rukwa Rift Basin, Tanzania

The Cretaceous Period is considered the archetypical greenhouse interval, yet there mounting evidence for intermittent cooler climatic phases throughout this geologic span. Few continental climate histories exist south of paleoequator, and fewer still Africa during time. Galula Formation one few exposed fossiliferous sedimentary successions from what now subequatorial that also contains paleosols spans both Early Late series. Bulk sediment pedogenic carbonate nodules were sampled located ~500 m stratotype section, including four lower Mtuka Member (Aptian-Cenomanian) upper Namba (Cenomanian-Campanian), to reconstruct paleoclimate paleoenvironment Rukwa Rift Basin. developed on channel fill deposits in a semi-arid amidst well-defined wet dry seasons predominantly generated vertic Calcisols. Geochemical morphological climofunctions determined mean annual precipitation (MAP) increased up-section 454 860 mm/yr, whereas δ18O values carbonates Bt horizon major-element paleothermometry estimated temperature (MAT) remained relatively steady, ranging between 12.9 13.9 °C Member. overlying formed overbank proximal main channels, sub-humid with little seasonality, forming mostly calcic Argillisols. under slightly wetter conditions, recording MAP 602 987 MAT estimates 10.3 12.5 °C. These data are consistent corresponding cool period spanned Aptian-Albian, cooling following Thermal Maximum. This work demonstrates temperate conditions prevailed Basin mid-Late Cretaceous.