Orbital-scale climate forcing of atmospheric dust flux in the Middle Jurassic

Abstract. Atmospheric dust fluxes are influenced by both human activities and natural climate variability, making it difficult to isolate climate-driven dust changes under modern warming. The Middle Jurassic greenhouse world provides a natural “experiment” to examine orbital-scale dust dynamics. Here, we reconstructed two high-resolution dust deposition records from mid- to high-latitude Middle Jurassic peatlands in China, using integrated petrographic, geochemical, palynological, isotopic, geochronological, and climate-model analyses. Our records reveal that the Junggar and Ordos basins hosted Aalenian ombrotrophic peatlands, with mineral matter primarily derived from atmospheric fallout, yielding atmospheric dust fluxes of 0.76–6.73 g m⁻² a⁻¹ and 1.53–27.36 g m⁻² a⁻¹, respectively. Dust fluxes are significantly linked to the hydrological cycle paced by astronomical forcing: Within published astrochronologic frameworks, humid intervals and reduced dust accumulation covary at timescales corresponding to ~405 kyr eccentricity and ~20 kyr precession. We conclude that Middle Jurassic atmospheric dust flux was primarily controlled by orbitally driven precipitation changes.