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Characterizing low-temperature aqueous alteration of Mars-analog basalts from Mauna Kea at multiple scales

Rasmussen, Brandon P. and Calvin, Wendy M. and Ehlmann, Bethany L. and Bristow, Thomas F. and Lautze, Nicole and Fraeman, Abigail A. and DesOrmeau, Joel W. (2020) Characterizing low-temperature aqueous alteration of Mars-analog basalts from Mauna Kea at multiple scales. American Mineralogist, 105 (9). pp. 1306-1316. ISSN 0003-004X. doi:10.2138/am-2020-7131.

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We performed a multi-scale characterization of aqueous alteration of Mars analog basaltic rock from a Mauna Kea drill core using high-resolution visible and short-wave infrared (VIS-SWIR) spectral imaging, scanning electron microscopy, X-ray diffraction, and point VIS-SWIR spectra. Several types of smectites, zeolites, and primary minerals were identified. Mineral classes were mapped in cut sections extracted from the drill core and used to represent the range of alteration products seen in field data collected over 1000 m depth (Calvin et al. 2020). Ten distinct spectral end-members identified in the cut sections were used to map the field point spectra. Trioctahedral Fe- and Mg-rich smectites were present toward the top of the zone of analysis (972 m below the surface) and increased in abundance toward the bottom of the drill core (1763 m depth). The mineralogy demonstrates a general trend of discontinuous alteration that increases in intensity with depth, with less pervasive phyllosilicate alteration at the top, several zones of different mixtures of zeolites toward the center, followed by more abundant phyllosilicates in the lowest sections. Distinctly absent are Fe-Mg phyllosilicates other than smectites, as well as carbonates, sulfates, and Al phyllosilicates such as kaolinite or illite. Furthermore, hematite was only detected in two of 24 samples. The suite of assemblages points to aqueous alteration at low-to-moderate temperatures at neutral to basic pH in low-oxygen conditions, with little evidence of extensive surface interaction, presenting a possible analog for an early Mars subsurface environment. We also present a library of VIS-SWIR spectra of the analyzed cut sections, including both spatial averages (i.e., unweighted linear mixtures) of spectral images of each cut section and single point spectra of the cut sections. This will allow for consideration of nonlinear mixing effects in point spectra of these assemblages from natural surfaces in future terrestrial or planetary work.

Item Type:Article
Related URLs:
URLURL TypeDescription
Calvin, Wendy M.0000-0002-6097-9586
Ehlmann, Bethany L.0000-0002-2745-3240
Bristow, Thomas F.0000-0001-6725-0555
Fraeman, Abigail A.0000-0003-4017-5158
Additional Information:© 2020 Mineralogical Society of America. Manuscript received May 24, 2019; Manuscript accepted June 2, 2020; Manuscript handled by Janice Bishop. We appreciate detailed reviews by Elizabeth Rampe and one anonymous reviewer who helped clarify and strengthen the manuscript. This project was funded in part by the Honors Undergraduate Research Program at the University of Nevada, Reno, and by the NASA Solar Systems Workings program Award no. 80NSSC19K0031 to W.M. Calvin. A portion of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.
Funding AgencyGrant Number
University of NevadaUNSPECIFIED
Subject Keywords:Visible to short-wave infrared spectroscopy, X-ray diffraction, scanning electron microscopy, Mars analog, natural zeolites, Mg/Fe smectites, aqueous alteration, Earth Analogs for Martian Geological Materials and Processes
Issue or Number:9
Record Number:CaltechAUTHORS:20200902-140600855
Persistent URL:
Official Citation:Brandon P. Rasmussen, Wendy M. Calvin, Bethany L. Ehlmann, Thomas F. Bristow, Nicole Lautze, Abigail A. Fraeman, Joel W. DesOrmeau; Characterizing low-temperature aqueous alteration of Mars-analog basalts from Mauna Kea at multiple scales. American Mineralogist ; 105 (9): 1306–1316. doi:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:105223
Deposited By: Tony Diaz
Deposited On:08 Sep 2020 23:47
Last Modified:16 Nov 2021 18:41

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