Alluvial Stratigraphic Response to Astronomical Climate Change: Numerical modelling and outcrop study in the Bighorn Basin, Wyoming, USA

Alluvial stratigraphy is influenced by both allogenic and autogenic factors, which are difficult to be distinguished from each other because they operate at overlapping spatial and temporal scales. Moreover, it remains uncertain whether autogenic dynamics can result in sedimentary cyclicity that resembles allogenically-driven stratigraphic products. In order to undertake this challenge and address the uncertainty, we first test what sedimentary processes can produce the alluvial cyclicity observed in outcrops by designing comparable scenarios in the process-based numerical modelling. In the meantime, we systematically characterize floodplain aggradation cycles by tracing them in a UAV-based photogrammetric model. Moreover, we comprehensively describe channelized sandstone bodies in the field and the model to reconstruct the paleogeography. Lastly, we configure the relationships between floodplain aggradation cycles and sandstone bodies of different river styles, based on which we identify the link between orbital forcing and alluvial stratigraphic response.