Purdue University Graduate School

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posted on 2023-08-02, 17:02 authored by Amanda RudolphAmanda Rudolph

The present-day sedimentary rock record on Mars provides insights into the early surface and subsurface geologic processes. Understanding the sediment characteristics in different environments can help to constrain the climate regimes, potential for habitability, and provide a record of ancient surface processes. The research presented in this dissertation uses complementary remote sensing techniques and datasets from rovers at the surface, satellites in orbit, and at terrestrial analogs that are relevant to current Mars exploration to better characterize alteration through water-rock alteration at multiple scales.

The martian field site for this work is Mt. Sharp, a 5-kilometer-high mountain in Gale crater that is predominantly composed of fluviolacustrine strata overlain by aeolian strata. At the rover-scale, the effects of large clay-mineral rich deposits were characterized using landscape- and hand lens-scale visible images from the Mastcam and MAHLI instruments, and multispectral visible/near-infrared images from Mastcam (445-1013 nm). Detailed analysis of the observed textures and spectral properties showed that the clay-rich deposits preserve the early surface environment, based on their lack of diagenetic features. While the regions immediately surrounding the clay-rich deposit experienced prolonged exposure to water, leading to enhanced alteration zones, and destroying characteristics from the early environment but providing insight into later water-rock processes.

At the orbital-scale, three visually distinct, dark-toned, and erosion-resistant layers were mapped and characterized using visible to short wave infrared hyperspectral (700-2650 nm) and image data. Two of these units have been identified as either aeolian or lacustrine through in situ rover investigations and the third unit will not be explored in situ so its origin can only be constrained through orbital analyses. We conducted a comparison of the morphological and spectral properties of the two known units to constrain whether their respective environments can be differentiated from orbit and apply this knowledge to the unknown third unit. The composition of all three units is similar, dominated by mafic minerals, suggesting a similar sediment source. The morphology is distinct between the lacustrine and aeolian units, with the unknown unit having similar morphology as the lacustrine unit, suggesting similar environments. We propose that the lacustrine unit in this study likely represent short-timescale transitions between wet and dry environments, where mafic sands are exposed to water prior to burial and lithification. While in the aeolian unit, most water-rock interactions occur upon lithification and later diagenesis. This has climatic implications in terms of the presence of surface water as these units were deposited as part of the original Mt. Sharp strata (i.e., the lacustrine unit) while some mantling existing topography (i.e., the aeolian and unknown units), representing similar processes but at a much later time.

The terrestrial analog field site for this dissertation was conducted in Iceland which represents a cold and wet/icy climate. We characterized sediments produced through glaciovolcanism and how they are sorted and altered through transport from source to sink along to characterize unique identifiers of glaciovolcanism that can be determined with Mars-relevant techniques. Decorrelation stretched visible images and lab visible/near-infrared reflectance and thermal-infrared emission data sets (400-2500 nm and 1200-400 cm-1, respectively) show that it is possible to differentiate sediments from glaciovolcanic and subaerial volcanic systems. In some glaciovolcanic systems, a high glass abundance (50-90 %) is observed in sediment grains due to the erosion of hyaloclastite and hyalotuff, deposits that form in water- and ice-magma interactions. These glass grains did not readily breakdown physically or chemically during transport, suggesting that they could still be observed on the martian surface today and be used to identify possible glaciovolcanic deposits.

The research described in this thesis improves the understanding of different geologic environments using remote sensing techniques and their climatic implications. This will help to better constrain early environments on Mars and identify areas where water may have been present through the rock record, as observed from the surface and from orbit.


Graduate Research Fellowship Program(GRFP)

Directorate for Education & Human Resources

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Zonta International Amelia Earhart Doctoral Fellowship

Indiana Space Grant Consortium Programs and Opportunities 2020-2024

National Aeronautics and Space Administration

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Degree Type

  • Doctor of Philosophy


  • Earth, Atmospheric and Planetary Sciences

Campus location

  • West Lafayette

Advisor/Supervisor/Committee Chair

Briony Horgan

Additional Committee Member 2

Michelle Thompson

Additional Committee Member 3

Darryl Granger

Additional Committee Member 4

Kristen Bennett