Methodological framework and evaluation of aeolian system sediment state: Wahiba Dune Field, Oman

At the fundamental level, the existence of a dune field is determined by a set of external (allogenic) boundary conditions. At any point in time, these boundary conditions control the sediment state of the aeolian system, defined by the separate components of sediment supply, sediment availability, and the transport capacity of the wind (sensu Kocurek and Lancaster, 1999). This paper provides a methodological framework to develop an aeolian system sediment state model using the Wahiba Dune Field of Oman, a system that incorporates at least 140 ka of dune field evolution. The framework consists of (1) assembling regional proxy datasets and simulations that encompass transient allogenic forcings; (2) deriving the impacts that these forcings will have upon system parameters inherent to the dune field, such as inland sediment yield, vegetation, coastal biogenic productivity, coastal shelf exposure, and the relative strength of the wind regime components; and (3) weighing these parameters for their control on sediment supply, sediment availability, and transport capacity of the wind. Dune chronological records for the Arabian subcontinent are subsequently evaluated with reference to the predictive sediment state for the Wahiba Dune Field. Principally, the sediment state model is found to imitate high frequency allogenic forcings that largely follow from Milankovitch and small-scale cycles. Overall, there is a general agreement with previous work, however, differences emerge in the predictions of the temporal dominance of southerly Indian summer monsoon winds versus NW Shamal winds. Shifts from these opposing wind systems are speculated to have promoted major reworking and probable redefinition of the composite linear megadunes that today dominate the dune field. Additionally, the resolution of the marine isotope stage (MIS) 5 dune field is brought into question and reinterpreted. The sediment state model ultimately proves useful in informing on the generation of a geological record in a complex aeolian system.