Quantification of dryland depositional environments across contrasting fluvio‐aeolian and fluvio‐lacustrine transects: An integrated subsurface and outcrop analogue study of the Organ Rock Formation, Utah, USA

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The standard subdivision of a distributive fluvial system (DFS) into proximal, medial and distal zones is typically based on the proportion of channel bodies and/or the degree of channel amalgamation, reflecting a downstream fining trend towards a mud‐prone terminal pinch‐out. However, in dryland settings, fluvial–aeolian interactions and limited accommodation maintain sand‐prone deposits basinward, complicating standard classifications. This study builds upon existing dryland DFS models by investigating the Organ Rock Formation and age‐equivalent strata of the Early Permian Cutler Group (Paradox Basin Province, southeastern Utah, USA). Data are presented as three quantified correlation panels comprising 15 outcrop logs and eight subsurface wells, temporally partitioned into intervals defined by climatic cyclicity. Two contrasting depositional transects are analysed: (1) a sand‐rich fluvio‐aeolian profile and (2) a mud‐rich fluvio‐lacustrine profile. An additional along‐strike profile captures lateral, distal transitions from an aeolian‐ to a lacustrine‐fringed fluvial pinch‐out. Preserved thicknesses are significantly greater (180 to 260 m) within the lacustrine pinch‐out than in the aeolian pinch‐out, reflecting enhanced subsidence in the Blanding Sub‐basin. This study proposes subdividing the dryland DFS into three zones based on the proportions of interpreted depositional environments: (1) braided‐dominated, (2) sinuous‐dominated and (3) terminal splay‐dominated zones. These zones reflect variations in discharge and host a predictable spectrum of associated depositional environments, governed primarily by climatic fluctuations and sediment supply rather than proximity to the sedimentary source. Wetting‐upward trends are generally characterised by the progressive emergence of sinuous fluvial systems and an increase in overall succession thicknesses. Drying‐upward intervals typically correspond to the initial expansion of the braided‐dominated zone during wet maxima, followed by aeolian advance and/or lacustrine contraction as aridity increases. This integrated outcrop‐subsurface analysis provides a predictive framework for assessing DFS architecture, reservoir distribution and basin‐scale allocyclicity in dryland systems, with broad implications for subsurface correlation and resource characterisation.