Geological Map of Petrified Dunes and Yardangs in Apollinaris Sulci

Abstract:

This research aims to understand past aeolian processes recorded in the petrified dunes at Apollinaris Sulci. The study area is located at 12.60 degrees S, 178.08 degrees E, between the Terra Cimmeria and Elysium Planitia regions of Mars. To study the area in detail, a geologic map was created of the petrified dunes and their surroundings. Units were identified and mapped using a CTX image mosaic basemap, and HiRISE images were used to study the region in greater resolution. Units were differentiated based on variations in rock formations, textures, and relief. Relative ages of the units were determined through cross-cutting relationships and crater density. Alongside the various units, dune crestlines and yardangs were also mapped. Based on photogeological mapping, this area in Apollinaris Sulci lies on the edge of an eroded crater rim. The petrified dune field is located at the center, with the lee slope facing south indicating a north to south wind direction. The transverse dunes have crescentic and marginal barchan morphologies with crestlines ranging from 100 m to 7 km in length. To the north is a yardang field cut into easternmost edge of the Medussae Fossae Formation. The average orientation of the yardangs is 169 degrees, indicating a formative wind direction of either SE to NW or NW to SE. Surrounding plains are covered in transverse aeolian ridges, both modern and preserved, with wind directions unique from previously mentioned units. These observations, in combination with interpretations of the local geology, show varied wind patterns over the history of Apollinaris Sulci.