Analyses of Sulfates in Chaos Regions on Mars

Sulfates are a common mineral identified from orbital remote sensing data of Mars. Although larger sulfate deposits including those in Valles Marineris, Meridiani Planum, and Gale crater continue to be investigated in great detail, studies focused on the smaller sulfate deposits found within the equatorial chaos regions were all conducted prior to 2013 by different teams using different data sets. These smaller sulfate deposits are expected to provide additional clues about how sulfates formed on Mars, particularly because they occur in the region between the larger sulfate deposits within Valles Marineris to the west and Meridiani Planum to the east. Thus, we propose a coordinated effort to investigate the sulfate-bearing deposits within four different chaos terrains, including Aram Chaos, Iani Chaos, Aureum Chaos, and Aurorae Chaos.

The objectives of the proposal are to: (i) map out the distribution of the light-toned deposits (which are the most likely units to contain sulfates) within each of the four chaos terrains; (ii) characterize their mineralogy, morphology, and stratigraphy of all sulfate deposits and establish their relationships to the chaos terrain and associated hydrologic system that enabled their formation; (iii) evaluate various processes that could have formed the sulfates within each chaos region; and (iv) compare the chaos sulfates to those studied elsewhere on Mars.

Five coordinated tasks have been identified to meet these objectives. In Task 1, we will analyze CTX, HRSC, and HiRISE images across each of the four chaos regions to identify, map, and characterize the light-toned deposits that could possibly be sulfate-bearing. In Task 2, we will analyze CRISM data to determine the composition of the light-toned deposits and other minerals within the chaos terrain and then produce mineral maps based upon the CRISM analyses. In Task 3, we will use Digital Terrain Models (DTMs) to determine stratigraphic relationships between the different kinds of sulfates within each deposit and also between the sulfates and other geologic units, such as the chaos terrain. In Task 4, we will compare the distribution, mineralogy, stratigraphy, and morphology of the sulfates within each of the four chaos regions and discuss how the geologic setting of each chaos region may have affected the characteristics of each sulfate deposit that formed within it. Finally, in Task 5 we will use our results to consider hypotheses describing the formation of sulfates on Mars with the goal of understanding how the sulfates formed in each chaos region and how they compare to other sulfate deposits elsewhere on Mars.

This new research will perform detailed morphologic, mineralogic, and stratigraphic analyses of the sulfate deposits within four different chaos geologic settings using the same data sets and mapping techniques that will enable a better comparison of the deposits within each chaos region. The results will provide critical new constraints on the role and timing of aqueous activity within the chaos regions, which fill in the spatial gap between the sulfates within Valles Marineris and the sulfates of Meridiani Planum. By expanding upon previous studies of individual chaos regions using additional and updated processing and data products of CRISM images in combination with newer HiRISE images and DTMs, we hope to explore how the sulfate deposits within each chaos region compare to each other in composition, distribution, morphology, and stratigraphy. Understanding the aqueous conditions and climate governing these sulfate-bearing units in the chaos regions will have important implications for climate and habitability on Mars because the sulfates formed in aqueous environments. The proposed project includes analyses of numerous orbital data sets, which makes the proposed study relevant to the MDAP program.