ANALYSIS OF A COLLAPSE ZONE IN THE ORSON WELLES CHAOS, XANTHE TERRA, MARS

Mineral composition, geomorphologic features, and potential recent sediment movement within the Orson Welles Chaos—a linear feature located between the Orson Welles crater and the Ganges Chasma in Xanthe Terra, Mars—were studied to understand the geologic and climate history of the region. The Orson Welles Chaos extends 280 kilometers long south-southwest and 70 kilometers wide of the Orson Welles crater, located at 0°, 314°. Review of published studies indicates this feature to be a complex cavernous system, containing features such as scarps, landslide deposits, linear and barchan dunes, extensional and en echelon faults, grabens, and craters. Data collected from the CTX camera, HiRISE camera, and CRISM spectrometer from the Mars Reconnaissance Orbiter was used to analyze small and medium scale geomorphologic features providing insight to the local processes.

In-depth mapping found distinct geomorphic units along the scarp walls and small crater floors as defined by boulder density, dune type, and sediment uniformity. Visual inspection of various valleys within the linear feature, which range from 2 to 30 kilometers wide, compounded with analysis using standard surface flow routing algorithms, found little evidence of surface fluvial processes, suggesting these features were formed by faulting or subsurface processes. Multispectral analysis found patches of relative mineral diversity in valleys based on infrared spectrometry. Future work will focus on formation models of this feature and the processes operating within it.