STATISTICAL DIFFERENTIATION OF STRUCTURAL LANDFORMS: WHAT SURFACE MORPHOLOGY AND SUBSURFACE STRUCTURE TELLS US ABOUT THE DIFFERENCES BETWEEN WRINKLE RIDGES AND LOBATE SCARPS

The lithosphere of Mars accommodates shortening strain through folding and thrust faulting, producing landforms historically, qualitatively categorized as wrinkle ridges or lobate scarps. The interpretation of landforms during mapping may affect our interpretations of where and how strains are recorded; however, we lack an in depth understanding of what drives differences between the landform types. Our goal is to develop a quantitative model for shortening landform classification based on surface morphology, subsurface structural geometry, and a wholistic surface-subsurface model, including an investigation of which shortening structure accommodates the most strain. We developed this model by first mapping 100 landforms in ArcMap, collecting parameters such as length, width, relief, asymmetry, and estimated strain. We then conducted a Discriminant Function Analysis (DFA) on these surface morphometrics. We then modeled the subsurface structural geology of 50 landforms using MOVE Structural Geology Modeling Software, and conducted a second DFA on subsurface metrics such as fault dip and depth. These analyses revealed that the three most important variables when classifying shortening structures from the surface were maximum breadth, forelimb (steep frontal) slope, and backlimb (shallow limb) length. When classifying shortening structures in the subsurface, vital metrics were dip and depth below the surface. Our results show that using the surface morphology and subsurface geometry together, wrinkle ridges and lobate scarps could be distinguished quantitatively 96% of the time. Importantly, our results also show that lobate scarps accommodate more strain, and they imply that studies should take into account landform type when interpreting local, regional, and global geological stress histories.