Chapin Brackett '98

    The crust of the Elysium Rise on Mars is marked by both extensional and compressional structural features. 1:2,000,000 scale Viking photomosaics were employed to map and identify these structures. The mapping of the Elysium Rise is part of an extensive project currently underway at the Jet Propulsion Laboratory. The goal of the project is to create a database containing every structural feature of the Martian crust.

    The data were digitized and compiled using ArcView 3.0. The completed map illustrates that trends are present for each structural type. Altered simple grabens are oriented N70ÁW, narrow simple grabens are both concentric to Elysium Mons and oriented N67ÁW, and wrinkle ridges trend N-S. Analysis of grabens surrounding Elysium Mons prove the concentric nature of the features and cross-cutting relationships offer relative ages of the structure types. The study indicates that the WNW grabens formed prior to the creation of the N-S ridges and that the concentric grabens are the youngest features in the region.

    A stress history of the Elysium Rise was created and compared to previous work on Elysium tectonics (Comer et al. 1985 and Hall et al. 1986). All three projects propose that the concentric grabens resulted from the local loading of the lithosphere by Elysium Mons. The N-S ridges are explained by two different mechanisms, global contraction and isostatic uplift of Tharsis. Similarly, both a dichotomy in the Martian crust and regional uplift are offered as causes of the WNW trend of grabens. The proposals are compared and the best-fit stress history is attained.