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R. T. Pappalardo, G. C. Collins, L. M. Prockter, J. G. Patel (Brown Univ.)
High-resolution Galileo imaging of Ganymede reveals "ridge and trough terrain" (sets of subparallel ridges and troughs) of a variety of morphologies in both dark and bright regions. The nature of Ganymede's ridge and trough terrains, including its bright "grooved terrain," offers important constraints on the interior and surface evolution of the satellite. We have recognized and categorized the morphological variety of Ganymede's ridge and trough terrains to understand the range in deformational styles and to derive a possible evolutionary sequence. Six principal morphological categories are recognized, with additional sub-types. The morphological classification suggests an evolutionary sequence from subdued (incipient) structures to more prominent (mature) structures in both dark and bright regions. This is inferred to correspond to the degree of strain which has deformed the ridge and trough terrain, consistent with measurements of extensional strain across several ridge and trough sets. The characteristics of highly deformed bright and dark terrains are very similar. This classification scheme and inferred evolutionary sequence will be used to investigate the implications of the style and variety of ridge and trough terrains for the satellite's local- and global-scale stress history, lithospheric character, and overall geological history. Morphological comparisons to ridge and trough sets on Europa will elucidate the origin of ridge and trough sets on that satellite, permitting comparison of deformation conditions on Ganymede and Europa. This work is supported by NASA's Jupiter System Data Analysis Program.
The author(s) of this abstract have provided an email address for comments about the abstract: pappalardo@brown.edu