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Reflectance spectra diversity of silica-rich materials: Sensitivity to environment and implications for detections on Mars

Rice, M. S. and Cloutis, E. A. and Bell, J. F., III and Bish, D. L. and Horgan, B. H. and Mertzman, S. A. and Craig, M. A. and Renaut, R. W. and Gautason, B. and Mountain, B. (2013) Reflectance spectra diversity of silica-rich materials: Sensitivity to environment and implications for detections on Mars. Icarus, 223 (1). pp. 499-533. ISSN 0019-1035.

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Hydrated silica-rich materials have recently been discovered on the surface of Mars by the Mars Exploration Rover (MER) Spirit, the Mars Reconnaissance Orbiter (MRO) Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), and the Mars Express Observatoire pour la Minéralogie, l’Eau, les Glaces, et l’Activité (OMEGA) in several locations. Having been interpreted as hydrothermal deposits and aqueous alteration products, these materials have important implications for the history of water on the martian surface. Spectral detections of these materials in visible to near infrared (Vis–NIR) wavelengths have been based on a H_2O absorption feature in the 934–1009 nm region seen with Spirit’s Pancam instrument, and on SiOH absorption features in the 2.21–2.26 μm range seen with CRISM. Our work aims to determine how the spectral reflectance properties of silica-rich materials in Vis–NIR wavelengths vary as a function of environmental conditions and formation. Here we present laboratory reflectance spectra of a diverse suite of silica-rich materials (chert, opal, quartz, natural sinters and synthetic silica) under a range of grain sizes and temperature, pressure, and humidity conditions. We find that the H_2O content and form of H_2O/OH present in silica-rich materials can have significant effects on their Vis–NIR spectra. Our main findings are that the position of the ∼1.4 μm OH feature and the symmetry of the ∼1.9 μm feature can be used to discern between various forms of silica-rich materials, and that the ratio of the ∼2.2 μm (SiOH) and ∼1.9 μm (H_2O) band depths can aid in distinguishing between silica phases (opal-A vs. opal-CT) and formation conditions (low vs. high temperature). In a case study of hydrated silica outcrops in Valles Marineris, we show that careful application of a modified version of these spectral parameters to orbital near-infrared spectra (e.g., from CRISM and OMEGA) can aid in characterizing the compositional diversity of silica-bearing deposits on Mars. We also discuss how these results can aid in the interpretation of silica detections on Mars made by the MER Panoramic Camera (Pancam) and Mars Science Laboratory (MSL) Mast-mounted Camera (Mastcam) instruments.

Item Type:Article
Related URLs:
URLURL TypeDescription
Rice, M. S.0000-0002-8370-4139
Cloutis, E. A.0000-0001-7301-0929
Bell, J. F., III0000-0002-2006-4074
Additional Information:© 2012 Elsevier Inc. Received 16 December 2011. Revised 19 September 2012. Accepted 20 September 2012. Available online 4 October 2012. We thank the MER and MRO engineering and science teams for providing the spectacular imaging and spectroscopic datasets that make the detection of silica-rich materials on Mars possible. Matt Smith, Josh Bandfield and two anonymous reviewers provided comments and that improved the quality of the manuscript. This work is supported by grants and contracts from the Canadian Space Agency (CSA), the Natural Sciences and Engineering Research Council (NSERC) and the University of Winnipeg (to EAC), and the NASA Mars Data Analysis Program. M.S.R. was also supported by a National Science Foundation Graduate Research Fellowship and a Zonta International Amelia Earhart Fellowship. E.A.C. wishes to thank the Canada Foundation for Innovation, the Manitoba Research Innovations Fund and CAS for their funding of the University of Winnipeg’s Planetary Spectrophotometer Facility. We also thank Paul Mann for providing laboratory measurements during the revision process, and Sue Atkinson, Bill Buhay, and Kim Tait and Ian Nicklin of the Royal Ontario Museum for providing some of the samples used in this study.
Funding AgencyGrant Number
Canadian Space Agency (CSA)UNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
University of WinnipegUNSPECIFIED
NASA Mars Data Analysis ProgramUNSPECIFIED
NSF Graduate Research FellowshipUNSPECIFIED
Zonta International Amelia Earhart FellowshipUNSPECIFIED
Canada Foundation for InnovationUNSPECIFIED
Manitoba Research and Innovation FundUNSPECIFIED
Subject Keywords:Spectroscopy; Mars; Mars, Surface
Issue or Number:1
Record Number:CaltechAUTHORS:20130411-104607862
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Official Citation:M.S. Rice, E.A. Cloutis, J.F. Bell III, D.L. Bish, B.H. Horgan, S.A. Mertzman, M.A. Craig, R.W. Renaut, B. Gautason, B. Mountain, Reflectance spectra diversity of silica-rich materials: Sensitivity to environment and implications for detections on Mars, Icarus, Volume 223, Issue 1, March 2013, Pages 499-533, ISSN 0019-1035, 10.1016/j.icarus.2012.09.021. (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:37889
Deposited By: Ruth Sustaita
Deposited On:11 Apr 2013 18:18
Last Modified:09 Mar 2020 13:19

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