Western Washington University Western CEDAR WWU Graduate School Collection WWU Graduate and Undergraduate Scholarship Summer 2017 Ongoing Exhumation and Recent Exposure of Sedimentary Outcrops on Mars Joshua M. Williams Western Washington University, [email protected] Follow this and additional works at: https://cedar.wwu.edu/wwuet Part of the Geology Commons Recommended Citation Williams, Joshua M., "Ongoing Exhumation and Recent Exposure of Sedimentary Outcrops on Mars" (2017). WWU Graduate School Collection. 606. https://cedar.wwu.edu/wwuet/606 This Masters Thesis is brought to you for free and open access by the WWU Graduate and Undergraduate Scholarship at Western CEDAR. It has been accepted for inclusion in WWU Graduate School Collection by an authorized administrator of Western CEDAR. For more information, please contact [email protected]. ONGOING EXHUMATION AND RECENT EXPOSURE OF SEDIMENTARY OUTCROPS ON MARS By Joshua M. Williams Accepted in Partial Completion of the Requirements for the Degree Master of Science Kathleen L. Kitto, Dean of the Graduate School ADVISORY COMMITTEE Chair, Dr. Melissa Rice Dr. Doug Clark Dr. Brady Foreman MASTER’S THESIS In presenting this thesis in partial fulfillment of the requirements for a master’s degree at Western Washington University, I grant to Western Washington University the non-exclusive royalty-free right to archive, reproduce, distribute, and display the thesis in any and all forms, including electronic format, via any digital library mechanisms maintained by WWU. I represent and warrant this is my original work, and does not infringe or violate any rights of others. I warrant that I have obtained written permissions from the owner of any third party copyrighted material included in these files. I acknowledge that I retain ownership rights to the copyright of this work, including but not limited to the right to use all or part of this work in future works, such as articles or books. Library users are granted permission for individual, research and non-commercial reproduction of this work for educational purposes only. Any further digital posting of this document requires specific permission from the author. Any copying or publication of this thesis for commercial purposes, or for financial gain, is not allowed without my written permission. Joshua M. Williams 26 May 2017 ONGOING EXHUMATION AND RECENT EXPOSURE OF SEDIMENTARY OUTCROPS ON MARS A Thesis Presented to The Faculty of Western Washington University In Partial Fulfillment of the Requirements for the Degree Master of Science By Joshua M. Williams May 2017 ABSTRACT Determining the habitability of ancient environments on Mars and their biosignature preservation potential is a primary goal of all recent Mars exploration missions. Because cosmogenic radiation destroys organic biosignatures at the Martian surface, freshly-exposed outcrops that have been previously protected by overburden provide potential sites where organic biosignatures could be observed. Scarp retreat is one common mechanism for exposing fresh outcrop surfaces. The absence of liquid water on Mars leaves aeolian processes to be the dominant eroding agent, and aeolian erosion drives scarp retreat by undercutting erosion- resistant cap rock that fails and breaks off from outcrops. This continual action creates bays and headlands. This study uses three methods to identify regions with freshly-exposed scarp surfaces using orbital images: (1) scarp orientation mapping; (2) identification of calved boulders; (3) identification of dust and drift deposition by color stretch analysis. These methods were consistent with surface observations from the Mars Science Laboratory (MSL) Curiosity rover in Gale crater. Scarp orientations in Gale crater show a distinct bay-signal (from the pattern of bays and headlands) that can be directly correlated with the known direction of ongoing aeolian scarp retreat. The bay-signal was also apparent at two of the Mars-2020 rover mission candidate landing sites: Eberswalde crater and Jezero crater. In a similar analysis of the Mars-2020 candidate landing sites Holden crater and Melas Basin, however, no clear bay-signal was identified. This work developed methods to detect recent scarp retreat on Mars and may provide a useful tool for identifying locations with high biosignature protection potential. iv ACKNOWLEDGEMENTS This manuscript greatly benefited from discussions with the late Nathan Bridges. Nathan was a science co-investigator with the Chemical Camera (ChemCam) instrument team. The ChemCam instrument is located on the Mast of the Curiosity rover, currently in Gale crater, Mars. Nathan was an aeolian processes expert and aided this study with his patient and valuable input. This manuscript was also benefited from input of M. Day and M. Chojnacki. We thank R. Sletten and B. Hallet (UW) for their input. WWU graduate student G. Speth is thanked for his assistance improving ArcGIS results in this study. The WWU Research-Writing Studio and C. Mead are recognized for their aid in improving this manuscript. Funding was provided by Western Washington University, the NASA Mars Science Laboratory Participating Scientist Program, and a Mars student travel grant to attend the third 2020 Mars rover landing site workshop. Thank you to the tireless work of my advisor Dr. Melissa Rice and my committee members: Dr. Doug Clark and Dr. Brady Foreman. Thank you to all the NASA/JPL affiliated scientists for their collaboration. Thank you to my grandmother Christine Williams for her never-ending support. v TABLE OF CONTENTS ABSTRACT ..................................................................................................................................... iv ACKNOWLEDGEMENTS ................................................................................................................. v LIST OF FIGURES AND TABLES ...................................................................................................... vii INTRODUCTION ............................................................................................................................. 1 METHODS ...................................................................................................................................... 4 Scarp Mapping ………………......................................................................................................... 4 Boulder Identification …….......................................................................................................... 5 RESULTS ......................................................................................................................................... 5 Gale crater ................................................................................................................................. 5 Eberswalde Crater…................................................................................................................... 6 Jezero ……................................................................................................................................... 7 Melas Chasma ........................................................................................................................... 8 Holden …............................................................................................................................. 9 DISCUSSION ................................................................................................................................... 9 Gale Crater Ground-Truth Study and Interpretations …..……………………............................... 9 Bay Signal Landform Evolution Model ............................................................................... 11 Sedimentary Sites ............................................................................................................... 12 Eberswalde crater ........................................................................................................... 12 Jezero .............................................................................................................................. 14 Melas Chasma ................................................................................................................. 15 Holden Crater ……............................................................................................................ 15 Future Work ................................................................................................................. 16 CONCLUSIONS ...................................................................................................................... 17 REFERENCES CITED ...................................................................................................................... 19 FIGURES ....................................................................................................................................... 24 TABLES ......................................................................................................................................... 50 vi LIST OF FIGURES AND TABLES Figure 1. Schematic of parallel scarp retreat at Yellowknife bay, Gale crater, Mars Figure 2. Boulder shedding off a scarp at Gale crater, Mars Figure 3. Yellowknife bay scarp orientations from orbital images and Curiosity rover images Figure 4. Yellowknife Bay area, Gale crater, Mars Figure 5. Gale crater scarp map area of Curiosity’s traverse Figure 6. Gale crater scarp map and orientations of scarps with partial sand accumulation