Ephemeral aeolian activity and harsh paleoenvironments in North China related to the late Guadalupian extinction event on land

The patterns and causes for the Guadalupian-Lopingian extinctions on land remain puzzling. Here, we reconstruct palaeoenvironments based mainly on the sedimentary environments from the eastern Ordos Basin, North China. Ephemeral aeolian activity in alluvial plains, as a critical marker of intermittent drought conditions, has been identified from the middle Sunjiagou Formation and can be well correlated between the Baode and Liulin areas in the eastern Ordos Basin. Thick dark red siltstones/mudstones with intercalated fine-grained sandstones rest above the aeolian sandstones, and were deposited on floodplains or oxbows adjacent to meandering channel belts. They can also be correlated by comparable mass burials of key tetrapod fossils including the pareiasaurs Shihtienfenia from Baode and Shansisaurus xuecunensis and Huanghesaurus liulinensis from Liulin, respectively. Notably, the fossil horizon at Baode shows a synchronous sharp carbon isotope negative excursion, decreased CIA, and a mercury peak, suggesting that the harsh paleoenvironment (reduced weathering intensity, arid and cool conditions) and potential influence of volcanism might have been important causes. A sandstone sample from the fossil horizon at Baode yields youngest detrital zircon ages of 266 ± 4 Ma, suggesting the maximum depositional age as late Guadalupian. Here, for the first time, we have identified late Guadalupian aeolian activity in North China based on field observations. We demonstrate that the harsh palaeoenvironment in North China may have caused the late Guadalupian tetrapod extinction events on land, before an event of sharp global warming related to the massive Emeishan large igneous province.