DOES THE AEOLIS PALUS LANDSCAPE NEAR KYLIE AND THE KIMBERLEY CONTAIN CLUES TO THE STRATIGRAPHIC ARCHITECTURE OF THE CURIOSITY FIELD SITE?

Near-vertical outcrop exposures in the Kylie and the Kimberley regions provide one of the best locations to attempt to assess the stratigraphic relationships of the Aeolis Palus rock units. We integrate outcrop rock characteristics observed in Curiosity images with the geomorphic expression of the landscape as seen in both orbiter data from Mars Reconnaissance Orbiter (MRO) High Resolution Imaging Science Experiment (HiRISE) camera to better understand the stratigraphic relationships.

The Kimberley and Kylie region is a rugged landscape characterized by low relief (<10 m) mesas and east-west trending escarpments. Two facies are associated with topographic benches in this region: a poorly sorted, weakly stratified pebble conglomerate, and a massive, dark-toned, vuggy sandstone. Several wall exposures exhibit shallow apparent dips of a few degrees to the north for bench-forming strata in rover images. Geometric planes fit to the top of topographic benches in the Kylie and the Kimberley region define a series of parallel surfaces gently dipping (2-3°) northward. The inclination of the topographic surface is similar to the apparent dip of the underlying strata, suggesting the presence of dip slopes.

The terrain Curiosity has traversed to date is classified into three principal stratigraphic groups: Bradbury, Mount Sharp, and Siccar Point groups [1, 2]. The Siccar Point group has rock units that unconformably drape paleotopography [3]. Based on the elevation range for the Siccar Point group, it is believed to unconformably overlay both the Mount Sharp and Bradbury groups, although the contact was only observed with rock units of the Mount Sharp group [2, 3]. Given the geometric similarities between the lower Mount Sharp strata observed in Curiosity images and the topographic benches in the Kylie and the Kimberley region, it raises the possibility that some of the caprocks in the study region could be part of the Siccar Point group. We discuss the possibility that rock units deposited after the deposition and exhumation of the lower strata of Mount Sharp may extend farther north than previously recognized.

[1] Grotzinger et al., 2015, Science, doi:10.1126/science.aac7575.

[2] Stack, K. M., 2017, LPSC, #1899.

[3] Watkins, J. et al., 2016, LPSC, #2939.