Triple oxygen and clumped isotopes in modern soil carbonate along an aridity gradient in the Serengeti, Tanzania

The isotopic composition of paleosol carbonates is used extensively to reconstruct past vegetation, climate, and altimetry, but poor constraints on soil evaporation temperature have limited the utility oxygen isotopes in studies. Recent advances carbonate clumped isotope thermometry (TΔ47) allow for independent controls temperature, influence remains unresolved. However, sensitivity 18O-17O-16O distributions kinetic fractionation makes it possible use triple (Δ′17O) track water. work shows Δ′17O lakes lacustrine carbonates, little known about variation their potential evaporation. For this study, we sampled soils across an aridity gradient Serengeti, Tanzania evaluate how tracks water Modern were collected from 11 sites a transect Serengeti Ecosystem where mean annual precipitation index range 499 846 mm yr−1 0.33 0.55, respectively. δ13C values −2.7 1.8‰ reflect C4 dominated grasslands, whereas δ18O vary by ∼8‰ along aridity. TΔ47 these average 23 °C (1σ± 4 °C), which does not significantly or with depth, likely due minimal at equator. Using temperatures each carbonate, reconstructed are up 6‰ higher than local springs, indicating considerable −162 −106 per meg decrease as both increase. Our results support hypothesis that drives variance arid climates, demonstrating paleoaridity constrain interpretations records.