Deepwater Polygonal Fault Systems as Terrestrial Analogs for Martian Polygonal Terrains
Discovery of polygonal terrains on Mars has prompted a thirty-year debate over how these features formed. The prevailing hypothesis is that Martian polygonal terrains formed by thermal contraction similar to that in terrestrial permafrost environments. However, seismic-reflection data also reveal the existence of polygonal fault systems in terrestrial Deepwater environments worldwide. How Deepwater polygonal fault systems form is still debated but similarities between Deepwater polygons and Martian polygons suggest that polygonal terrains on the northern plains of Mars could have formed subaqueously. The presence of calcium carbonate, aqueous minerals, and salts on the polygonal bearing Phoenix landing site also supports our subaqueous hypothesis. Physical models indicate that multidirectional extension can generate disaggregation of polygonal features under the influence of a slope and a mobile substrate. These findings support the idea of a Late Hesperian-Early Amazonian ocean on the northern plains of Mars.
AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California