Remote Sensing of Impact Crater-Exposed Subsurface Lithologies and Martian Rayed Crater Systems

Impact cratering is ubiquitous, energetic and fundamental geologic process acting on the solid planetary bodies. As a consequence, craters provide planetary scientists with useful information regarding the surface and subsurface properties of planetary bodies. Specific mineral and lithologic compositions can be ascertained via craters in two ways: 1) by the remote sensing of crater-exposed subsurface materials, or 2) by studying the differentiated meteorites (e.g., lunar, Martian, etc.) ejected from their surfaces by highenergy impacts under specific conditions. As a proof of concept for subsurface-crater mapping, remote sensing techniques were applied to a terrestrial impact structure. Visible-near infrared (VNIR), short-wavelength infrared (SWIR), and thermal infrared (TIR) data were used to map the subsurface geology of a portion of Devon Island (High Canadian Arctic) via the impact-exposed subsurface lithologies of the 23-kilometer diameter Haughton impact structure. The results from the “blind” remote sensing of Haughton suggest that the spectral and lithologic mapping techniques used in this study can also be used to understand subsurface geology of Mars. TIR images from Thermal Emission Imaging System (THEMIS) onboard Mars Odyssey were used in a similar fashion to spectrally map craters within the Isidis basin on Mars. Complementary hyperspectral information from the Thermal Emission Spectrometer (TES) allowed mineral and litho-type compositional determinations, albeit at a much lower spatial resolution. An olivine-rich basaltic unit mapped at the surface and was linked with a subsurface occurrence via exposure from impact craters occurring within the basin. These two studies (Chapters 2 and 3) demonstrate that, in conjunction with surface mapping, impact craters provide a natural “window” for understanding the stratigraphy and petrogenesis of planetary crusts. In another project presented here (Chapter 4), rayed crater systems on Mars, which are preferentially found on the younger lava plains, has led to the hypothesis that rayed craters may have been the launch sites for the Martian meteorites recovered on Earth. This hypothesis is supported by morphologic and thermophysical evidence, as well as the most current modeling of Martian meteorite ejection.