Stress and Deformation on Mars, 20-9314

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Principal Investigators
David A. Ferrill
Darrell W. Sims
Alan P. Morris
Danielle Wyrick
Deborah Waiting
Clark Chapman
D. Marius Necsoiu
Nathan Franklin
John Stamatakos

Inclusive Dates: 05/06/02 - Current

Background - An important gap in the geologic characterization of Mars is a detailed planet-scale analysis of structural features, stress field distribution and evolution, and an approach for analyzing the stresses resolved on structures during and after their formation. Results of such investigations should be employed where mission planning includes landing-site objectives such as drilling, groundwater and mineral exploration, placement of seismic monitoring networks, or exploration for water-related mineral deposits that might harbor Martian fossils or even current life forms. SwRI® has unique capabilities to perform these analyses and is a recognized technical leader in this area of Mars research. The first objective of this project is to use remotely sensed data from Mars, particularly Mars Orbiter Laser Altimeter (MOLA) data, to map structural features on the surface of Mars. The second objective is to use advanced structural geology concepts and new technologies, including SwRI-developed 3DStress™ software, to characterize the stress fields in the Martian crust, and the resulting resolved stresses on faults and fractures that may influence ongoing deformation activity and subsurface fluid movement.

Approach - In this project, a five-step approach is used to achieve the objectives. First, remotely sensed data, including MOLA and other relevant data, from NASA, are processed to enhance structural features, and permit mapping structures exposed at the surface of Mars such as folds, faults, and extension-fracture networks. Second, structural domain determination and stress field analysis are performed, for which the primary tool will be 3DStress™, to determine assemblages of contemporaneous structures and the stress orientations responsible for deformation in different regions. Earth analogs will be used to augment an understanding of deformation features on Mars. Cross-cutting relationships (of structures with respect to each other and with respect to craters) with crater-counting based surface exposure age determinations are then used to determine relative ages of structural assemblages and stress fields. Further, likely deformation and stress field controls on subsurface fluid movement, mineralization, heat flow, and seismic activity on Mars are evaluated. Finally, work accomplished during the project will be published, where possible in the form of manuscripts for peer-reviewed journals.

Accomplishments - Staff have performed extensive work on downloading and processing photographic image data and laser altimetry data and using geographic information systems approaches to co-register data sets. Mapping faults and transferring fault traces into 3DStress™ to analyze stress fields on Martian normal faults have been performed for part of Utopia Plantia, as well as analyzing differences between deformation styles on Mars compared with Earth and the role of lower gravity on Mars compared with Earth. Fault shapes based on rock mechanics information for basalt and andesite, depth vs. density profiles, and gravitational acceleration were analyzed. This analysis led to the interpretation of a zone of dilational faulting, similar to the upper two kilometers of the Earth's crust, that may be present on Mars and extend more than 2.5 times deeper on Mars than on Earth, which can explain the origin of pit chains on Mars. This interpretation has important implications for groundwater movement and mineralization in the crust of Mars. Results of these analyses have so far led to seven conference presentations and one journal manuscript. In addition, one NASA grant proposal was submitted as a direct product of this project, and two other NASA proposals and a Special Session at the Fall 2003 meeting of the American Geophysical Union ("Faulting and Fault Related Processes on Planetary Surfaces") were outgrowths of this project.

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