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Tracing Carbonate Formation, Serpentinization, and Biological Materials With Micro-/Meso-Scale Infrared Imaging Spectroscopy in a Mars Analog System, Samail Ophiolite, Oman

Leask, Ellen K. and Ehlmann, Bethany L. and Greenberger, Rebecca N. and Pinet, Patrick and Daydou, Yves and Ceuleneer, Georges and Kelemen, Peter (2021) Tracing Carbonate Formation, Serpentinization, and Biological Materials With Micro-/Meso-Scale Infrared Imaging Spectroscopy in a Mars Analog System, Samail Ophiolite, Oman. Earth and Space Science, 8 (11). Art. No. e2021EA001637. ISSN 2333-5084. doi:10.1029/2021ea001637.

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Visible-shortwave infrared (VSWIR) imaging spectrometers map composition remotely with spatial context, typically at many meters-scale from orbital and airborne data. Here, we evaluate VSWIR imaging spectroscopy capabilities at centimeters to sub-millimeter scale at the Samail Ophiolite, Oman, where mafic and ultramafic lithologies and their alteration products, including serpentine and carbonates, are exposed in a semi-arid environment, analogous to similar mineral associations observed from Mars orbit that will be explored by the Mars-2020 rover. At outcrop and hand specimen scales, VSWIR spectroscopy (a) identifies cross-cutting veins of calcite, dolomite, magnesite, serpentine, and chlorite that record pathways and time-order of multiple alteration events of changing fluid composition; (b) detects small-scale, partially altered remnant pyroxenes and localized epidote and prehnite that indicate protolith composition and temperatures and pressures of multiple generations of faulting and alteration, respectively; and (c) discriminates between spectrally similar carbonate and serpentine phases and carbonate solid solutions. In natural magnesite veins, minor amounts of ferrous iron can appear similar to olivine's strong 1-μm absorption, though no olivine is present. We also find that mineral identification for carbonate and serpentine in mixtures with each other is strongly scale- and texture-dependent; ∼40 area% dolomite in mm-scale veins at one serpentinite outcrop and ∼18 area% serpentine in a calcite-rich travertine outcrop are not discriminated until spatial scales of <∼1–2 cm/pixel. We found biological materials, for example bacterial mats versus vascular plants, are differentiated using wavelengths <1 μm while shortwave infrared wavelengths >1 μm are required to identify most organic materials and distinguish most mineral phases.

Item Type:Article
Related URLs:
URLURL TypeDescription
Leask, Ellen K.0000-0002-3220-4003
Ehlmann, Bethany L.0000-0002-2745-3240
Greenberger, Rebecca N.0000-0003-1583-0261
Pinet, Patrick0000-0002-1933-5631
Ceuleneer, Georges0000-0002-6198-4205
Kelemen, Peter0000-0003-4757-0855
Additional Information:© 2021 The Authors. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. Issue Online: 28 October 2021; Version of Record online: 28 October 2021; Accepted manuscript online: 03 October 2021; Manuscript accepted: 20 September 2021; Manuscript revised: 14 September 2021; Manuscript received: 03 January 2021. Thanks to the other members of our field party, Mathieu Rospabé, Mathieu Benoit, Said Al Musharrafi and Layla al-Habsi, and to the Bedouin family of Said Ghofar who hosted our field campsite in Wadi Dima. We appreciate also the help of Mohamed Al Araimi and of Mohamed Al Batashi from the Public Authority of Mining of Oman in reviewing and permitting our samples to bring to Caltech for further analyses. Thanks to Jesse Tarnas and Brad Garczynski who provided reviews that helped to improve this manuscript. We appreciate the support of a NASA Mars Fundamental Research grant to B.L.E for field work and laboratory analysis (#NNX12AB42G), a NASA Planetary Major Equipment grant to B.L.E. for the imaging spectrometer (#NNX13AG74G), a NASA Mars Data Analysis grant to B.L.E. for comparison to Mars orbital data (#80NSSC19K1594), and an NSERC PGS-D scholarship to E.K.L. R.N.G. thanks a grant from the American Philosophical Society's Lewis and Clark Fund for Exploration and Field Research in Astrobiology for supporting partial field and travel costs. P.P., Y.D., and G.C. were supported by the French Space Agency, Centre National d'Etudes Spatiales (CNES), in a project in conjunction with the Mars-Express mission OMEGA instrument. Data Availability Statement: Datasets used in this research are available in the CaltechDATA site (Leask et al., 2021, and at the CaltechDATA site (Leask & Ehlmann, 2017, for data from our previous Leask and Ehlmann (2016) publication.
Funding AgencyGrant Number
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
American Philosophical SocietyUNSPECIFIED
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Subject Keywords:carbonate; serpentine; Oman; hyperspectral imaging; infrared spectroscopy; Mars
Issue or Number:11
Record Number:CaltechAUTHORS:20211015-222204956
Persistent URL:
Official Citation:Leask, E. K., Ehlmann, B. L., Greenberger, R. N., Pinet, P., Daydou, Y., Ceuleneer, G., & Kelemen, P. (2021). Tracing carbonate formation, serpentinization, and biological materials with micro-/meso-scale infrared imaging spectroscopy in a Mars analog system, Samail Ophiolite, Oman. Earth and Space Science, 8, e2021EA001637.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:111482
Deposited By: George Porter
Deposited On:18 Oct 2021 16:26
Last Modified:03 Nov 2021 17:52

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