Palaeo-environmental evolution of Central Asia during the Cenozoic: new insights from the continental sedimentary archive of the Valley of Lakes (Mongolia)

Abstract. The Valley of Lakes basin (Mongolia) contains a unique continental sedimentary archive, suitable for constraining the influence tectonics and climate change on aridification Central Asia in Cenozoic. We identify provenance, (post)depositional environment palaeo-climate based sedimentological, petrographical, mineralogical, (isotope) geochemical signatures recorded authigenic detrital silicates as well soil carbonates succession spanning from ∼34 to 21 Ma. depositional setting was characterized by an ephemeral braided river system draining prograding alluvial fans, with episodes lake, playa or open-steppe sedimentation. Metamorphics northern adjacent Neoarchean late Proterozoic hinterlands provided continuous influx silicate detritus basin, indicated K–Ar ages muscovite (∼798–728 Ma) discrimination function analysis. clay fraction is dominated illite–smectite “hairy” illite (K–Ar ∼34–25 Ma), which formed during coupled petrogenesis precipitation hydrothermal fluids originating major basalt flow events (∼32–29 ∼29–25 Ma). Changes hydroclimate are δ18O δ13C profiles mineral weathering patterns, indicating that comparatively humid semi-arid conditions prevailed late(st) Eocene, changing into arid Oligocene back early Miocene. Aridification steps at ∼34–33, ∼31, ∼28 ∼23 Ma coincide some high-latitude ice-sheet expansion inferred marine deep-sea records. This suggests long-term variations ocean–atmosphere circulation patterns due pCO2 fall, reconfiguration ocean gateways Antarctica could have impacted regime basin. conclude triggered reduced moisture westerly winds driven Cenozoic forcing exhumation Tian Shan Altai Mountains modulated global events.