Global Morphological Mapping of Strike-Slip Structures on Ganymede

Abstract:

Many inferences of strike-slip faulting and distributed shear zones on Ganymede suggest that strike-slip tectonism may be important to the structural development of its surface and in the transition from dark to light (grooved) materials. To better understand the role of strike-slip tectonism in shaping Ganymede’s multifaceted surface, we identify and map key examples of strike-slip morphologies (en echelon structures, strike-slip duplexes, laterally offset pre-existing features, and possible strained craters) from Galileo and Voyager images. Here we present the current state of these global mapping efforts, with particular emphasis given to complex structures associated with grooved terrain (e.g. Nun Sulci) and terrains transitional from dark to light terrain (e.g. the boundary between Nippur Sulcus and Marius Regio). These results are being synthesized into a global database representing an inferred sense of shear for fractures on Ganymede. This, combined with existing observations of extensional features, is helping to narrow down the range of possible principal stress directions that could have acted at the regional or global scale to produce grooved terrain. Moreover, these data sets, combined with mechanical models of shear failure and global stress sources, are providing constraints for testing possible mechanisms for grooved terrain formation on Ganymede.