Examining natural rock varnish and weathering rinds with laser-induced breakdown spectroscopy for application to ChemCam on Mars.

A laser-induced breakdown spectroscopy (LIBS) instrument is traveling to Mars as part of ChemCam on the Mars Science Laboratory rover. Martian rocks have weathered exteriors that obscure their bulk compositions. We examine weathered rocks with LIBS in a martian atmosphere to improve interpretations of ChemCam rock analyses on Mars. Profile data are analyzed using principal component analysis, and coatings and rinds are examined using scanning electron microscopy and electron probe microanalysis. Our results show that LIBS is sensitive to minor compositional changes with depth and correctly identifies rock type even if the series of laser pulses does not penetrate to unweathered material.

[1]  D. Krinsley.  Models of rock varnish formation constrained by high resolution transmission electron microscopy , 1998 .

[2]  M. Cremaschi.  The rock varnish in the Messak Settafet (Fezzan, Libyan Sahara), age, archaeological context, and paleo‐environmental implication , 1996 .

[3]  S. Clegg,et al.  Multivariate analysis of remote laser-induced breakdown spectroscopy spectra using partial least squares, principal component analysis, and related techniques , 2009 .

[4]  J. Bolger,et al.  Semi-Quantitative Laser-Induced Breakdown Spectroscopy for Analysis of Mineral Drill Core , 2000 .

[5]  Richard V. Morris,et al.  Calibration of the MSL/ChemCam/LIBS Remote Sensing Composition Instrument , 2011 .

[6]  R. Dorn,et al.  In situ weathering rind erosion , 2005 .

[7]  D. Ming,et al.  Localization and Physical Properties Experiments Conducted by Spirit at Gusev Crater , 2004, Science.

[8]  Bruce A. Campbell,et al.  Radar probing of planetary regoliths: An example from the northern rim of Imbrium basin , 2006 .

[9]  John P. Grotzinger,et al.  Beyond water on Mars , 2009 .

[10]  D. Ming,et al.  Water alteration of rocks and soils on Mars at the Spirit rover site in Gusev crater , 2005, Nature.

[11]  Remote laser‐induced breakdown spectroscopy analyses of Dar al Gani 476 and Zagami Martian meteorites , 2006 .

[12]  R. C. Wiens,et al.  Nonlinear mapping technique for data visualization and clustering assessment of LIBS data: application to ChemCam data , 2011, Analytical and bioanalytical chemistry.

[13]  C. G. Engel,et al.  CHEMICAL DATA ON DESERT VARNISH , 1958 .

[14]  R E Arvidson,et al.  Basaltic rocks analyzed by the Spirit Rover in Gusev Crater. , 2004, Science.

[15]  N. Thiagarajan,et al.  Trace-element evidence for the origin of desert varnish by direct aqueous atmospheric deposition , 2004 .

[16]  Carlton C. Allen,et al.  Desert Varnish of the Sonoran Desert: Optical and Electron Probe Microanalysis , 1978, The Journal of Geology.

[17]  J. Noller,et al.  Rock and Mineral Weathering , 2013 .

[18]  J. Francis,et al.  AMS Radiocarbon and Cation-Ratio Dating of Rock Art in the Bighorn Basin of Wyoming and Montana , 1993, American Antiquity.

[19]  W. Chesworth,et al.  The weathering of basalt and relative mobilities of the major elements at Belbex, France , 1981 .

[20]  S. Murchie,et al.  A model for formation of dust, soil, and rock coatings on Mars: Physical and chemical processes on the Martian surface , 2002 .

[21]  R. Wiens,et al.  Analysis of Water Ice and Water Ice/Soil Mixtures Using Laser-Induced Breakdown Spectroscopy: Application to Mars Polar Exploration , 2004, Applied spectroscopy.

[22]  John B. Ritter,et al.  Use of Multiparameter Relative-Age Methods for Age Estimation and Correlation of Alluvial Fan Surfaces on a Desert Piedmont, Eastern Mojave Desert, California , 1989, Quaternary Research.

[23]  S. Brantley,et al.  Rates of weathering rind formation on Costa Rican basalt , 2004 .

[24]  D. Cremers,et al.  Use of the vacuum ultraviolet spectral region for laser-induced breakdown spectroscopy-based Martian geology and exploration , 2005 .

[25]  Jeffrey R. Johnson,et al.  Veneers, rinds, and fracture fills: Relatively late alteration of sedimentary rocks at Meridiani Planum, Mars , 2008 .

[26]  Stewart Clegg,et al.  Optimization of laser-induced breakdown spectroscopy for rapid geochemical analysis , 2010 .

[27]  B. Kennedy,et al.  An Overview of the Mars Science Laboratory Sample Acquisition, Sample Processing, and Handling Subsystem , 2010 .

[28]  Cristian A. D'Angelo,et al.  Analysis of Minerals and Rocks by Laser-Induced Breakdown Spectroscopy , 2011 .

[29]  E. Wolfe,et al.  Geologic map of the SP Mountain part of the San Francisco Volcanic Field, north-central Arizona , 1987 .

[30]  M. Porter,et al.  Diversity of rock varnish bacterial communities from Black Canyon, New Mexico , 2010 .

[31]  W. Broecker,et al.  Rock Varnish: Recorder of Desert Wetness? , 2001 .

[32]  W. Broecker,et al.  A clue regarding the origin of rock varnish , 1999 .

[33]  V. Hodge,et al.  Prompt detection of alpha particles from 210Po: another clue to the origin of rock varnish? , 2005, Journal of environmental radioactivity.

[34]  C. Weitz,et al.  Opaline silica in young deposits on Mars , 2008 .

[35]  M. M. Osterloo,et al.  Chloride-Bearing Materials in the Southern Highlands of Mars , 2008, Science.

[36]  R. Harmon,et al.  Laser-induced breakdown spectroscopy – An emerging chemical sensor technology for real-time field-portable, geochemical, mineralogical, and environmental applications , 2006 .

[37]  R. S. Perry,et al.  Desert varnish: evidence for cyclic deposition of manganese , 1978, Nature.