Mapping and Analysis of Wrinkle Ridges in the Aeolis Dorsa Region, Mars: Implications for Stress Fields and Geologic Substrates

Wrinkle ridges are tectonic geologic features found throughout the inner solar system. They are asymmetric, curvilinear ridges with a complex morphology interpreted to be due to deformation along thrust faults. Previous studies have mostly focused on large wrinkle ridges with maximum widths and lengths measuring tens and hundreds of kilometers, respectively. However, recent high-resolution data of the Martian surface have revealed small wrinkle ridges in the Aeolis Dorsa (AD) region along the global dichotomy boundary. Mapping and analyzing such small-scale wrinkle ridges can provide valuable information on tectonic processes operating at the regional or local scale. The null hypothesis driving this work is that wrinkle ridges in the AD region reflect regional deformation consistent with larger wrinkle ridges in the surrounding Cerberus plains and circum-Elysium region. Alternatively, they might reflect deformation that was more localized and different for different areas within AD. I derived information on shortening, strain, and principal stress directions in the AD region, as expressed by these small-scale wrinkle ridges. I mapped the locations of the wrinkle ridges using ArcMap software and created digital elevation models to determine their dimensions. Shortening due to folding was quantified based on the integrated lengths of topographic profiles and shortening due to faulting was derived from the differences in relief across the ridges and assumed dip angles. From each shortening estimate, I calculated values for strain. The geographic orientations were used to determine the principal stress directions. Cross-cutting relationships suggest formation postdated fluvial deposition and predated alluvial fan formation. The number of wrinkle ridges mapped in AD did not meet the minimum number required for a robust statistical test of clustering, but I visually identified several geospatially distinct clusters of wrinkle ridges. These clusters exhibited distinct orientations and amounts of strain. This result supports the alternate hypothesis of more than one stress field (or driver) operating in different locations, possibly simultaneously, during wrinkle ridge formation.