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Characterization of Moist Environments at Mawrth Vallis, Mars Through Comparison with Volcanic Alteration on the Island of Kauai

Presentation #212.02 in the session Martian Geomorphology, Ice Layers, Crust, and Habitability (Poster)

Published onOct 23, 2023
Characterization of Moist Environments at Mawrth Vallis, Mars Through Comparison with Volcanic Alteration on the Island of Kauai

CRISM images of the Mawrth Vallis region on Mars were analyzed for halloysite outcrops for comparison with alteration of volcanic material observed at Waimea Canyon on the island of Kauai. A newly available CRISM image mapping technique [1] was employed to view small outcrops of halloysite compared to the more widespread Al-smectite and allophane units, all of which occur stratigraphically above the ~200 m thick Fe/Mg-smectite unit. These small halloysite outcrops are observed throughout the Mawrth Vallis region and often occur together with alunite and kaolinite in the southeast part of this phyllosilicate-rich region. Al-rich allophane and imogolite are typically the first alteration products of volcanic ash. These poorly crystalline materials then mature to Al-smectite (montmorillonite) in wet/dry settings where water ponds, or to halloysite in settings with abundant rainfall and high drainage [2]. Characterizing these sites where halloysite is present rather than montmorillonite may be related to local variations in the environment.

Analyses of altered volcanic material at Waimea Canyon State Park on the Hawaiian island of Kauai found that abundant halloysite and goethite formed in rainy environments there [3]. Chemistry, mineralogy, and spectral properties were characterized for seven samples from four sites at Waimea Canyon in that study. The halloysite-bearing outcrops we are observing at Mawrth Vallis in CRISM images tend to be about 50-100 m across, which is larger than the halloysite-bearing outcrops at Waimea Canyon, but generally smaller than the montmorillonite-bearing regions at Mawrth Vallis. Our investigation is characterizing the locations of these Al-rich alteration materials in relation to their stratigraphy in order to inform our understanding of the geologic history and likely environmental variations.

[1] Saranathan A. M. & M. Parente (2021) Adversarial feature learning for improved mineral mapping of CRISM data, Icarus, 355, 114107.

[2] Bishop J. L. et al. (2008) Reflectance and emission spectroscopy study of four groups of phyllosilicates: Smectites, kaolinite-serpentines, chlorites and micas, Clay Miner., 43, 35-54.

[3] Gruendler K. E. W. (2023) Characterizing Altered Volcanic Rocks from Waimea Canyon, Kauai, 54th Lunar Planet. Sci. Conf., Abstract #1892.

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