Statistical Characterization of a Confined Submarine Fan System: the Pennsylvanian Lower Atoka Formation, Ouachita Mountains, USA

Our knowledge of submarine fan deposits has historically relied heavily on qualitative field and subsurface observations and interpretations, but recent studies using statistical analyses have enhanced the understanding of submarine fan sub-environments, including the degree of confinement, stratigraphic patterns, and potential control factors. The purpose of this study is to improve the quantitative understanding of synorogenic submarine fan deposition at foreland basin settings with a statistical approach. A suite of statistical methods is integrated and developed (Hurst Statistics/ rescaled range analysis, bed thickness frequency distribution analysis, Markov Chains, and time-series analysis), and applied to the well understood Pennsylvanian lower Atoka submarine fan system in the Ouachita Mountains, United States for this purpose. The results of the Hurst Statistics and bed thickness analyses corroborate qualitative interpretations that (1) the lower Atoka is lobe-dominated, and (2) the southeastern (wedge-top) portion of the system is more strongly confined than the northern (foredeep) portion. The Markov Chains and time-series analyses reveal the prevalence (56%) of stratigraphic orderliness and cyclicity; these results are used to discuss potential intrinsic and extrinsic controls on the turbidite sandstone recurrence cycles, which are otherwise difficult to distinguish qualitatively. The results of this study demonstrate that these integrated statistical methods can be utilized to quantify uncertainty in depositional interpretations of outcrops with limited exposures or 1D subsurface (e.g., well-log, core) datasets.