Martian wrinkle ridges morphometry and kinematics correlation from Trishear Forward Modelling

Wrinkle ridges (WRs) are among the most prevalent tectonic landforms observed on terrestrial planetary bodies, characterized by highly variable relief. They are interpreted as folds overlying blind thrusts, which can reach reliefs of 100’s meters and widths of several 10’s kilometers. The formation and subsurface characteristics of WRs is still debated with unresolved questions, including: i) geometry and likely structural style of associated blind faults, ii) fault depth, iii) number and role of faults, iv) amount of shortening. Several modelling methods have been proposed, however, none of them completely describe the entire spectrum of observations related to WRs morphometry and kinematics.

In this work, we conduct a 2D to 3D geometrical and kinematic reconstruction of a set of globally distributed WRs by applying Trishear and Fault-Parallel-Flow integrated forward kinematic modelling. The methodology allows to model complex fault geometries by assuming area conservation and plane-strain deformation, to determine the fault geometry and kinematics that best fits the observed topography and the measured outcropping faults dip angles.

Our results demonstrate the reliability of the trishear method to model planetary WRs and provide an improvement in understanding Mars’ lithospheric mechanical stratigraphy and WRs kinematics. We demonstrate how the wrinkly and complex nature of WRs can be related to the presence of multiple faults, which accommodate shortening differently. We suggest the presence of a heterogeneous stratigraphy composed of alternations of weaker and friction detachments which promote fault activity characterized by sequential deformation of backthrusts, synthetic thrusts.

The results of the trishear kinematic modelling indicate correlations of the main morphometric parameters of WRs with the geometry and kinematics of the faults. WRs characterized by a higher relief are driven by larger amounts of horizontal along-fault slip, while the broader the width of the main crest, the deeper and more spaced are the faults below the crest (i.e., master fault and possible backthrust). The location of the hinge zone of the main crest, corresponds to the fault dip change at depth.