GEOLOGIC MAPPING OF A TERRACED FAN DEPOSIT IN DUKHAN CRATER, XANTHE TERRA, MARS

Located in the northeastern edge of the Xanthe Terra region of Mars, the Dukhan Crater is an impact feature with a diameter of approximately 33 km. The southern margin of the crater is breached by an incised channel system that feeds a terraced fan with at least seven distinct terraces (latitude 7.59°S and 321.03°E). The feeder channel system measures 9 km long and displays very low sinuosity; the fan has a diameter of < 5 km. Orbital data for the fan includes: (1) a pair of high-resolution stereo images taken by the High Resolution Imaging Science Experiment (HiRISE); (2) several Context Camera (CTX) images. The purpose of this study was to conduct geologic mapping of the fan and determine what, if any, small-scale sedimentary features could be resolved using available orbital imagery.

Geologic mapping was completed using ArcGIS Pro, and detailed observation of the fan, channel, and crater revealed the presence of distinct, mappable units. Units were defined based on albedo as well as the presence of unique small-scale features such as dunes, boulders, terrain roughness, and crater size/frequency. These observations were used to define eight general stratigraphic zones: (1) a rugged crater floor unit; (2) a smooth crater floor unit; (3) distal fan terraces; (4) light-colored fan boundaries; (5) dark, rough fan terraces; (6) banded middle fan terraces; (7) smooth proximal fan terraces; and (8) young, aeolian cover. Linear and point features such as dunes and boulders, respectively, were also mapped on the HiRISE imagery in ArcGIS Pro.

The next steps of this work include analysis of aeolian deposits (i.e., crest orientation, size, location) and boulder distributions. Preliminary results indicate that there are multiple styles of aeolian transport with ripples developed on the backs of large dune forms and dunes preferentially located within sheltered topographic areas. Likewise, boulder distribution on the fan does not appear uniform, and a higher proportion of large boulders characterize some units, e.g. the light-colored fan boundary unit. Future work will focus on integrating these results to develop a model for terraced fan formation in Dukhan Crater.