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Pushing the Limits of Geological Mapping Outside the Earth: 3-D Modelling of Strike-Slip and Extensional Fault Systems in Meridiani Planum Region, Mars

Abstract

GIS and geological modelling software has enabled geoscientists to undertake a wide range of 3D topographic and geological reconstructions of the Earth's crust based on georeferenced data. More recently, the wealth of Mars-referenced data made available by NASA and HiRise at the University of Arizona has opened up lots of new possibilities for off-world modelling and tectonic reconstructions. The results of a new geological study of the fault systems in the Meridiani Planum of Mars are presented in this work. The stratigraphic sequence in the Eagle and Endurance craters on Mars has been described as finely laminated sandstones (eolian dune and sand sheet facies; Squyres et al., 2004, Squyres & Knoll, 2005 after the Mars Exploration Rover Opportunity survey) with the uppermost half metre characterised by festoon cross-bedding lamination indicating subaqueous deposition. A high component of silicates and sulphate salts (e.g. sulphate anhydrate, epsomite, and gypsum) have been also described (Squyres et al., 2004). These presence of these evaporite deposits has been used by some workers to suggest that surface water once existed on Mars. However, these deposits may have also played an important role in the structural development of the Martian crust, by behaving as potential décollement levels at depth. Our new work on the tectonic features in the Meridiani Planum region was carried out in Midland Valley's Move” software. Initial data consisted of a Digital Terrain Model and orthoimages (NASA/JPL/University of Arizona/USGS). 3D bedding and fault surfaces were created using tools that allow us to calculate multiple dip domains based on the intersection between a planar geological feature and the topography. We have interpreted the fault systems of the Meridiani Planum as right-lateral strike-slip faults with associated releasing bends, which resulted in extension causing folding of the bedding. Bedding ranges from sub-horizontal in the southern domain where strike-slip prevails to nearly 40 degrees in the central and northern domains, where a more complex interaction between strike-slip and extensional faults can be observed.