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R. T. Pappalardo (LASP, U. Colorado), F. Nimmo (Ames), B. Giese (DLR)
We identify sites of apparent flexural uplift associated with grooved terrain formation and rifting on Ganymede using Galileo stereo-derived topography from the G28 orbit. The estimated effective elastic thickness Te is found to be 0.2-0.6 km for a nominal Young's modulus of 1 GPa. Using a viscoelastic model of the ice lithosphere we find that the ratio of Te to conductive lid thickness is < 0.5. The inferred local heat flux during the period of deformation is < 480 mW m-2, and probably close to 60 mW m-2. This value is an order of magnitude greater than the present-day radiogenic heat flux. Based on fault block topography, the stresses required to cause fault motion are estimated as ~1 MPa. Both the high heat flux and the high stresses are consistent with estimates of these quantities during an episode of transient tidal heating in Ganymede's past.