BEDDING GEOMETRY OF BENCH-FORMING STRATA IN THE KYLIE AND KIMBERLEY REGIONS OF GALE CRATER

The geologic history of Aeolis Palus, the region between the rim of Gale Crater to the north and the mound of sedimentary rock that occupies much of the north-central crater (Aeolis Mons, informally called Mt. Sharp), is extremely complicated. The Kylie and Kimberley regions are important erosional windows into the Gale crater floor sedimentary deposits. Bedrock exposures at these sites were used to determine the three-dimensional sedimentary architecture. At each site, the stratigraphically lowest exposed unit corresponds to a distinct NE-SW banded terrain in orbital images and south-dipping (5-15°) sandstones in rover images. These inclined sandstones have been previously interpreted as deltaic deposits sourced from the northwest crater rim. Higher in the stratigraphic section at each of these sites are several distinct, erosion-resistant rock layers that form low relief (~1 m) topographic benches. We investigate the sedimentary characteristics and bedding geometry of these bench-forming strata.

We examined and integrated stereo images and topography from the HiRISE camera with rover-based images from Curiosity’s Mastcam and Navcam instrument. Bedding geometry was determined using planar fits to elevation points extracted along the benches identified in HiRISE images.

Three bench-forming strata were identified and mapped discontinuously over lateral distances of 0.5-1 km. Two of the bench-forming strata are capstones (top of local stratigraphic column) that correspond to massive sandstone, while one of the benches occurs mid-way down the valley walls at Kylie and is a poorly-sorted conglomerate. These strata dip gently to the north-northwest at 2-3°. The dip magnitude and orientation of bedding are consistent with that observed in lower Mt. Sharp strata located ~7 km to the southeast, suggesting that central mound layers were originally more laterally extensive. Our ongoing work is investigating the implications for the depositional history that formed Aeolis Palus and lower Mt. Sharp strata.