ODDLY ORGANIZED NETWORKS OF THE SOUTHERN OZARK DOME: IDENTIFYING AND UNDERSTANDING STRUCTURALLY CONTROLLED ANOMALIES IN DRAINAGE NETWORKS

Since the advent of topographic data, geologists have noted portions of drainage networks where valleys appear unusually linear or where multiple valleys align. These ‘drainage network lineaments’ are often taken to reflect geologic structure (e.g., faults or fracture networks), either through extension of outcroppings of those structures, or through expectations of erosion through damaged rock. However, a growing body of work has also come to understand planview drainage network patterns as emergent and self-organized through studies generally focused in homogenous lithologies. Here we explore two questions; what competition exists between self-organizing tendencies of landscapes and the influence of structurally controlled planes of weakness and how might we objectively identify anomalies in drainage networks? Non-dimensional landscape evolution models demonstrate how network self-organization the can impede the formation of network lineaments. We then use a study area in mostly horizontal Paleozoic strata in tectonically inactive northern Arkansas to provide natural examples of drainage network lineaments across a gradient in drainage density and local relief. We use a series of natural examples of drainage networks showing structural controls of anomalies to highlight challenges with the existing approaches to identify these features. We propose three alternative approaches to quantifying anomalies; 1) spectral analysis to identify characteristic valley orientations, 2) normalizing observations of drainage directions, and 3) programmatically identifying co-linearity of networks, which we showcase in an investigation of the southern Ozark Dome.