DEFINING THE LIMITS OF TECTONIC REACTIVATION ON MARS USING NUMERICAL MODELING AND EARTH ANALOGUE ANALYSIS

Numerical modeling experiments of the Ouachita Mountains, USA suggest that the reactivation of mantle-lithosphere scars from relict subduction zone sutures can influence mountain belt geometry during intracontinental orogenesis on Earth. We question (1) if scar geometry is also reflected in smaller scale structures and (2) if similar regional scale structures on Mars imply that mantle-lithosphere reactivation and intracontinental deformation could have occurred.

To investigate structural geometries on Earth, we collected 677 structural measurements in the Stanley shale and Jackfork sandstone of the Maumelle Chaotic Zone (MCZ) in the Ouachita Mountains of Arkansas. We then used MOVE Structural Geology Software (MOVE) to build two-dimensional (2-D) cross sections using fault-propagation modeling. A subsequent three-dimensional (3-D) model and strain analysis of the region was conducted in MOVE to visualize the overall geometry of structures and their relation to mantle-lithosphere reactivation. Fieldwork in the MCZ as well as 2-D and 3-D modeling efforts resulted in geometries such as north and south verging, asymmetric fault-propagation folds, overturned front limbs, structural duplexes and overall northward tectonic transport. We conclude that changes in vergence and fault geometry result from the reactivation of a relict subduction zone and lithological properties. We interpret the MCZ as a part of a foreland fold and thrust belt.

Similar structural geometries found in our study are also present on the surface of rocky planets, such as lobate scarps on Mars. To explore if ‘Earth-like’ mantle-lithosphere reactivation is possible for (one-plate planet) Mars, we hypothesize that mantle-lithosphere scars could be created during asteroid induced impact events or sub-lithospheric convection cycles. We use the 3-D numerical modeling code ASPECT to explore the possibility of mantle-lithosphere reactivation and subsequent intracontinental deformation geometries on Mars, constrained by Martian thermodynamic and rheological parameters.