MAPPING AND ANALYSIS OF SMALL-SCALE WRINKLE RIDGES IN THE AEOLIS DORSA REGION, MARS

Wrinkle ridges (WRs) are geologic features found on terrestrial planetary bodies and are widely interpreted to have formed by tectonic compression and folding above blind thrust faults. Mapping and analysis of WRs can contribute to a better understanding of the tectonic and geologic history of a region. WRs on Mars have previously been observed at a wide range of spatial scales, from regional (100s of km along strike) to local (10s of km along strike). For this study, we have identified and mapped WRs in the Aeolis Dorsa (AD) region of Mars as part of an official USGS geologic map of the AD region. These ridges are smaller in length (<50 km) and width (<3 km) than many of the WRs previously studied on Mars and other planetary bodies, and thus can be used to understand tectonic processes at a more local scale. Our null hypothesis is that WRs in AD formed under a regionally homogeneous stress regime. To test this hypothesis and to quantify the magnitude of deformation of the WRs, we derived their orientation, dimensions, and amount of shortening strain. During mapping, WRs were classified into certainty levels – certain, probable, and possible – based on several characteristic criteria from the literature on WRs. Preferred orientations were determined based on measured geographic orientation. Results from 19 mapped ridges indicate two preferred orientations: one centered at N15W and one at N35E. WRs in AD have an average length of 13.5 km, average width of 6 km, and average height of 74 m. We determined the amount of shortening and strain from faulting and folding across each WR using data from topographic profiles. The average shortening from folding is 50 m and the average strain is 0.013. The average shortening from faulting is 85 m and the average strain is 0.017. Statistical analysis of shortening and strain measurements of all WRs will be used to determine whether they are statistically similar or different across the region. The two preferred orientations of WRs in AD suggest that the principal compressive stress direction did change during WR formation.