Pengfei Hou, Leslie Wood, Zane Richards Jobe

Submarine fans deposited in structurally complex settings record important information on basin evolution and tectonic-sedimentary relationships but are often poorly preserved in outcrops due to post-depositional deformation. This study integrates both new field data as well as data compiled from literature to demonstrate the spatial facies variability of the deep-water lower Atoka formation (Lower Pennsylvanian) that occupies a structurally complex early foreland-basin setting. The lower Atoka outcrops in the Ouachita Mountains and the southern Arkoma Basin in the USA are divided into three structural-depositional zones: foredeep, wedge-top, and foreland. Although the mean paleoflow is axial, each zone exhibits unique patterns in facies distribution. The foredeep consists of a large westward-prograding fan and a small eastward-prograding fan on the western part and exhibits significant longitudinal and lateral facies changes. The wedge-top consists of a westward-prograding fan and exhibits subtle longitudinal facies change. The foreland consists of small slope channel and fan systems along the northern and western margins. We interpret the characteristics of facies distributions in the three zones as the result of different combinations of lateral structural-topographic confinement, sediment supply, and paleogeographic locations. This study provides an improved understanding of the lower Atoka deepwater system and has implications for the tectonic-sedimentation relationship on the southern Laurentia continental margin during the Ouachita Orogeny.