JOVIAN SYSTEM DATA ANALYSIS PROGRAM PROPOSAL SUMMARY

The objectives of the proposed research are (1) to conduct both global and local-scale geologic mapping of parts of Europa so as to characterize the styles and distribution of different centers of volcanic and tectonic activity, constrain the sequence of events in the formation of different plains units and to evaluate the timing relations between the formation of different tectonic structures and (2) to quantify the amount of both compressional and extensional strain that has occurred on various scales. Global-scale mapping will be performed for a region imaged during the G1 orbit that contains extensive outcrops of mottled and bright plains, both of which are cross cut by sets of linea and triple bands. In the latter part of the first year and during the second year of the proposed work, the analysis will be expanded to the region further to the west (-50°S to 55°N and longitudes 230° to 317°) that was imaged during the E4 orbit and covers the E6, Conamara Chaos area. Local-scale mapping using high resolution data of a complex region of volcanic centers and ridges imaged in E4 and the E6 data of Conamara Chaos will provide a means to compare sequences of events at various scales and to extrapolate units identified at high resolution to other parts of the satellite. Using the results of the first part of this study as a basis for more detailed work, the second objective of this research is to estimate the amount of strain or displacement that has occurred on different scales. This will be done through regional-scale mapping of an area of "wedges" imaged during the E11 orbit and by measuring the amount of lateral displacement of different crustal blocks. Within this part of the study, comparisons will be made to the other icy Galilean Satellites. For example, based on their morphologic similarities, ridge and groove structures within part of the "wedge" terrain appear to be similar to those in Uruk Sulcus on Ganymede, suggesting that the "wedges" on Europa may be made up of rotated fault blocks. Senske, D. A., J. W. Head, R. Pappalardo, G. Collins, R. Greeley, K. Magee, G. Neukum, C. Chapman, Stratigraphy of Uruk Sulcus, Ganymede as Revealed by High-resolution Galileo Images, submitted to Icarus, 1998. Senske, D. A., R. Greeley, J. Head, R. Pappalardo, R. Sullivan, M. Carr, P. Geissler, J. Moore, and the Galileo Imaging Team, Geologic Mapping of Europa: Unit Identification and Stratigraphy at Global and Local Scales,LPSC XXIX, 1743-1744, 1998. Prockter, L.M., J.W. Head, D.A Senske, R.T. Pappalardo, G. Neukum, R. Wagner, U. Wolf, J. Oberst, B. Giese, J.M. Moore, C.R. Chapman, P. Helfenstein, R. Greeley, H.H. Breneman, and M.J.S. Belton. Dark terrain on Ganymede: Geological mapping and interpretation of Galileo Regio at high resolution, Icarus, in press, 1998. Simonelli, D. P., J. Veverka, D. A. Senske, F. P. Fanale, G. Schubert, and M. J. S. Belton, Galileo Search for SO2-Frost Condensation on Io's Nightside, Icarus, in press, 1998.