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Title: Chemistry, Mineralogy, and Grain Properties at Namib and High Dunes, Bagnold Dune Field, Gale Crater, Mars: A Synthesis of Curiosity Rover Observations: Bagnold Dune Sands Composition

Abstract

The Mars Science Laboratory Curiosity rover performed coordinated measurements to examine the textures and compositions of aeolian sands in the active Bagnold dune field. The Bagnold sands are rounded to subrounded, very fine- to medium- sized (~45-500 µm) with ≥6 distinct grain colors. In contrast to sands examined by Curiosity in a dust-covered, inactive bedform called Rocknest and soils at other landing sites, Bagnold sands are darker, less red, better sorted, have fewer silt-sized or smaller grains, and show no evidence for cohesion. Nonetheless, Bagnold mineralogy and Rocknest mineralogy are similar with plagioclase, olivine, and pyroxenes in similar proportions comprising >90% of crystalline phases, along with a substantial amorphous component (35% ± 15%). Yet, Bagnold and Rocknest bulk chemistry differ. Bagnold sands are Si-enriched relative to other soils at Gale crater, and H 2O, S, and Cl are lower relative to all previously measured martian soils and most Gale crater rocks. Mg, Ni, Fe, and Mn are enriched in the coarse-sieved fraction of Bagnold sands, corroborated by VNIR spectra that suggest enrichment of olivine. Together, patterns in major element chemistry and volatile release data indicate two distinctive volatile reservoirs in martian soils: (1) amorphous components in the sand-sized fraction (representedmore » by Bagnold) that are Si-enriched, hydroxylated alteration products and/or impact or volcanic glasses; and (2) amorphous components in the fine fraction (<40 µm; represented by Rocknest and other bright soils) that are Fe-, S-, and Cl-enriched with low Si and adsorbed and structural H 2O.« less

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [4];  [5]; ORCiD logo [6]; ORCiD logo [7]; ORCiD logo [1]; ORCiD logo [8]; ORCiD logo [9]; ORCiD logo [10];  [11]; ORCiD logo [12];  [4]; ORCiD logo [13]; ORCiD logo [14]; ORCiD logo [15];  [13]; ORCiD logo [10];  [1] more »; ORCiD logo [11];  [16];  [1]; ORCiD logo [12]; ORCiD logo [17];  [18];  [1];  [17]; ORCiD logo [19];  [16]; ORCiD logo [20]; ORCiD logo [21]; ORCiD logo [22]; ORCiD logo [6]; ORCiD logo [19]; ORCiD logo [23]; ORCiD logo [1];  [12]; ORCiD logo [24];  [1] « less
  1. California Inst. of Technology (CalTech), Pasadena, CA (United States). Jet Propulsion Lab.
  2. Malin Space Science Systems, San Diego, CA (United States)
  3. Jacobs Technology, Houston, TX (United States); NASA Johnson Space Center, Houston, TX (United States)
  4. Univ. of Arizona, Tucson, AZ (United States). Dept. of Geosciences
  5. Russian Academy of Sciences (RAS), Moscow (Russian Federation). Space Research Inst.
  6. California Inst. of Technology (CalTech), Pasadena, CA (United States)
  7. Cornell Univ., Ithaca, NY (United States). Cornell Center for Astrophysics and Planetary Sciences
  8. Washington Univ., St. Louis, MO (United States). Dept. of Earth and Planetary Sciences
  9. NASA Ames Research Center (ARC), Moffett Field, CA (United States). Exobiology Branch
  10. Johns Hopkins Univ., Laurel, MD (United States)
  11. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
  12. Univ. of Toulouse (France). Inst. for Research in Astrophysics and Planetology (IRAP)
  13. Arizona State Univ., Tempe, AZ (United States). School of Earth and Space Exploration
  14. Univ. of Guelph, ON (Canada)
  15. Southwest Research Inst. (SwRI), San Antonio, TX (United States). Dept. of Space Science
  16. Univ. of Toulouse (France). Inst. for Research in Astrophysics and Planetology (IRAP), Midi-Pyrenees Observatory
  17. NASA Johnson Space Center, Houston, TX (United States)
  18. Johns Hopkins University Applied Physics Laboratory, Laurel MD USA
  19. Univ. of New Brunswick, Fredericton NB (Canada). Planetary and Space Science Centre
  20. Univ. of Hawaii, Honolulu, HI (United States). Dept. of Geology and Geophysics
  21. Inst. for Research in Astrophysics and Planetology (IRAP), Toulouse (France); German Aerospace Center (DLR), Berlin (Germany). Inst. of Optical Sensor Systems
  22. Stony Brook Univ., NY (United States). Dept. of Geosciences
  23. Planetary Science Inst., Tucson AZ (United States)
  24. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE; National Aeronautics and Space Administration (NASA)
OSTI Identifier:
1396141
Report Number(s):
LA-UR-17-27682
Journal ID: ISSN 2169-9097
Grant/Contract Number:
AC52-06NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Planets
Additional Journal Information:
Journal Volume: 122; Journal Issue: 12; Journal ID: ISSN 2169-9097
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; Planetary Sciences

Citation Formats

Ehlmann, B. L., Edgett, K. S., Sutter, B., Achilles, C. N., Litvak, M. L., Lapotre, M. G. A., Sullivan, R., Fraeman, A. A., Arvidson, R. E., Blake, D. F., Bridges, N. T., Conrad, P. G., Cousin, A., Downs, R. T., Gabriel, T. S. J., Gellert, R., Hamilton, V. E., Hardgrove, C., Johnson, J. R., Kuhn, S., Mahaffy, P. R., Maurice, S., McHenry, M., Meslin, P. -Y., Ming, D. W., Minitti, M. E., Morookian, J. M., Morris, R. V., O'Connell-Cooper, C. D., Pinet, P. C., Rowland, S. K., Schröder, S., Siebach, K. L., Stein, N. T., Thompson, L. M., Vaniman, D. T., Vasavada, A. R., Wellington, D. F., Wiens, R. C., and Yen, A. S. Chemistry, Mineralogy, and Grain Properties at Namib and High Dunes, Bagnold Dune Field, Gale Crater, Mars: A Synthesis of Curiosity Rover Observations: Bagnold Dune Sands Composition. United States: N. p., 2017. Web. doi:10.1002/2017JE005267.
Ehlmann, B. L., Edgett, K. S., Sutter, B., Achilles, C. N., Litvak, M. L., Lapotre, M. G. A., Sullivan, R., Fraeman, A. A., Arvidson, R. E., Blake, D. F., Bridges, N. T., Conrad, P. G., Cousin, A., Downs, R. T., Gabriel, T. S. J., Gellert, R., Hamilton, V. E., Hardgrove, C., Johnson, J. R., Kuhn, S., Mahaffy, P. R., Maurice, S., McHenry, M., Meslin, P. -Y., Ming, D. W., Minitti, M. E., Morookian, J. M., Morris, R. V., O'Connell-Cooper, C. D., Pinet, P. C., Rowland, S. K., Schröder, S., Siebach, K. L., Stein, N. T., Thompson, L. M., Vaniman, D. T., Vasavada, A. R., Wellington, D. F., Wiens, R. C., & Yen, A. S. Chemistry, Mineralogy, and Grain Properties at Namib and High Dunes, Bagnold Dune Field, Gale Crater, Mars: A Synthesis of Curiosity Rover Observations: Bagnold Dune Sands Composition. United States. doi:10.1002/2017JE005267.
Ehlmann, B. L., Edgett, K. S., Sutter, B., Achilles, C. N., Litvak, M. L., Lapotre, M. G. A., Sullivan, R., Fraeman, A. A., Arvidson, R. E., Blake, D. F., Bridges, N. T., Conrad, P. G., Cousin, A., Downs, R. T., Gabriel, T. S. J., Gellert, R., Hamilton, V. E., Hardgrove, C., Johnson, J. R., Kuhn, S., Mahaffy, P. R., Maurice, S., McHenry, M., Meslin, P. -Y., Ming, D. W., Minitti, M. E., Morookian, J. M., Morris, R. V., O'Connell-Cooper, C. D., Pinet, P. C., Rowland, S. K., Schröder, S., Siebach, K. L., Stein, N. T., Thompson, L. M., Vaniman, D. T., Vasavada, A. R., Wellington, D. F., Wiens, R. C., and Yen, A. S. Mon . "Chemistry, Mineralogy, and Grain Properties at Namib and High Dunes, Bagnold Dune Field, Gale Crater, Mars: A Synthesis of Curiosity Rover Observations: Bagnold Dune Sands Composition". United States. doi:10.1002/2017JE005267. https://www.osti.gov/servlets/purl/1396141.
@article{osti_1396141,
title = {Chemistry, Mineralogy, and Grain Properties at Namib and High Dunes, Bagnold Dune Field, Gale Crater, Mars: A Synthesis of Curiosity Rover Observations: Bagnold Dune Sands Composition},
author = {Ehlmann, B. L. and Edgett, K. S. and Sutter, B. and Achilles, C. N. and Litvak, M. L. and Lapotre, M. G. A. and Sullivan, R. and Fraeman, A. A. and Arvidson, R. E. and Blake, D. F. and Bridges, N. T. and Conrad, P. G. and Cousin, A. and Downs, R. T. and Gabriel, T. S. J. and Gellert, R. and Hamilton, V. E. and Hardgrove, C. and Johnson, J. R. and Kuhn, S. and Mahaffy, P. R. and Maurice, S. and McHenry, M. and Meslin, P. -Y. and Ming, D. W. and Minitti, M. E. and Morookian, J. M. and Morris, R. V. and O'Connell-Cooper, C. D. and Pinet, P. C. and Rowland, S. K. and Schröder, S. and Siebach, K. L. and Stein, N. T. and Thompson, L. M. and Vaniman, D. T. and Vasavada, A. R. and Wellington, D. F. and Wiens, R. C. and Yen, A. S.},
abstractNote = {The Mars Science Laboratory Curiosity rover performed coordinated measurements to examine the textures and compositions of aeolian sands in the active Bagnold dune field. The Bagnold sands are rounded to subrounded, very fine- to medium- sized (~45-500 µm) with ≥6 distinct grain colors. In contrast to sands examined by Curiosity in a dust-covered, inactive bedform called Rocknest and soils at other landing sites, Bagnold sands are darker, less red, better sorted, have fewer silt-sized or smaller grains, and show no evidence for cohesion. Nonetheless, Bagnold mineralogy and Rocknest mineralogy are similar with plagioclase, olivine, and pyroxenes in similar proportions comprising >90% of crystalline phases, along with a substantial amorphous component (35% ± 15%). Yet, Bagnold and Rocknest bulk chemistry differ. Bagnold sands are Si-enriched relative to other soils at Gale crater, and H2O, S, and Cl are lower relative to all previously measured martian soils and most Gale crater rocks. Mg, Ni, Fe, and Mn are enriched in the coarse-sieved fraction of Bagnold sands, corroborated by VNIR spectra that suggest enrichment of olivine. Together, patterns in major element chemistry and volatile release data indicate two distinctive volatile reservoirs in martian soils: (1) amorphous components in the sand-sized fraction (represented by Bagnold) that are Si-enriched, hydroxylated alteration products and/or impact or volcanic glasses; and (2) amorphous components in the fine fraction (<40 µm; represented by Rocknest and other bright soils) that are Fe-, S-, and Cl-enriched with low Si and adsorbed and structural H2O.},
doi = {10.1002/2017JE005267},
journal = {Journal of Geophysical Research. Planets},
number = 12,
volume = 122,
place = {United States},
year = {Mon Jun 12 00:00:00 EDT 2017},
month = {Mon Jun 12 00:00:00 EDT 2017}
}

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  • The Curiosity rover has analyzed various detrital sedimentary rocks at Gale Crater, among which fluvial and lacustrine rocks are predominant. Conglomerates correspond both to the coarsest sediments analyzed and the least modified by chemical alteration, enabling us to link their chemistry to that of source rocks on the Gale Crater rims. Here, we report the results of six conglomerate targets analyzed by Alpha-Particle X-ray Spectrometer and 40 analyzed by ChemCam. The bulk chemistry derived by both instruments suggests two distinct end-members for the conglomerate compositions. The first group (Darwin type) is typical of conglomerates analyzed before sol 540; it hasmore » a felsic alkali-rich composition, with a Na 2O/K 2O > 5. The second group (Kimberley type) is typical of conglomerates analyzed between sols 540 and 670 in the vicinity of the Kimberley waypoint; it has an alkali-rich potassic composition with Na 2O/K 2O < 2. The variety of chemistry and igneous textures (when identifiable) of individual clasts suggest that each conglomerate type is a mixture of multiple source rocks. Conglomerate compositions are in agreement with most of the felsic alkali-rich float rock compositions analyzed in the hummocky plains. The average composition of conglomerates can be taken as a proxy of the average igneous crust composition at Gale Crater. Finally, the differences between the composition of conglomerates and that of finer-grained detrital sediments analyzed by the rover suggest modifications by diagenetic processes (especially for Mg enrichments in fine-grained rocks), physical sorting, and mixing with finer-grained material of different composition.« less
  • The Mars Science Laboratory rover Curiosity encountered potassium-rich clastic sedimentary rocks at two sites in Gale Crater, the waypoints Cooperstown and Kimberley. These rocks include several distinct meters thick sedimentary outcrops ranging from fine sandstone to conglomerate, interpreted to record an ancient fluvial or fluvio-deltaic depositional system. Furthermore, from ChemCam Laser-Induced Breakdown Spectroscopy (LIBS) chemical analyses, this suite of sedimentary rocks has an overall mean K 2O abundance that is more than 5 times higher than that of the average Martian crust. The combined analysis of ChemCam data with stratigraphic and geographic locations then reveals that the mean K 2Omore » abundance increases upward through the stratigraphic section. Chemical analyses across each unit can be represented as mixtures of several distinct chemical components, i.e., mineral phases, including K-bearing minerals, mafic silicates, Fe-oxides, and Fe-hydroxide/oxyhydroxides. Possible K-bearing minerals include alkali feldspar (including anorthoclase and sanidine) and K-bearing phyllosilicate such as illite. Mixtures of different source rocks, including a potassium-rich rock located on the rim and walls of Gale Crater, are the likely origin of observed chemical variations within each unit. Physical sorting may have also played a role in the enrichment in K in the Kimberley formation. The occurrence of these potassic sedimentary rocks provides additional evidence for the chemical diversity of the crust exposed at Gale Crater.« less
  • The Windjana drill sample, a sandstone of the Dillinger member (Kimberley formation, Gale Crater, Mars), was analyzed by CheMin X-ray diffraction (XRD) in the MSL Curiosity rover. From Rietveld refinements of its XRD pattern, Windjana contains the following: sanidine (21% weight, ~Or 95); augite (20%); magnetite (12%); pigeonite; olivine; plagioclase; amorphous and smectitic material (~25%); and percent levels of others including ilmenite, fluorapatite, and bassanite. From mass balance on the Alpha Proton X-ray Spectrometer (APXS) chemical analysis, the amorphous material is Fe rich with nearly no other cations—like ferrihydrite. The Windjana sample shows little alteration and was likely cemented bymore » its magnetite and ferrihydrite. From ChemCam Laser-Induced Breakdown Spectrometer (LIBS) chemical analyses, Windjana is representative of the Dillinger and Mount Remarkable members of the Kimberley formation. LIBS data suggest that the Kimberley sediments include at least three chemical components. The most K-rich targets have 5.6% K 2O, ~1.8 times that of Windjana, implying a sediment component with >40% sanidine, e.g., a trachyte. A second component is rich in mafic minerals, with little feldspar (like a shergottite). A third component is richer in plagioclase and in Na 2O, and is likely to be basaltic. The K-rich sediment component is consistent with APXS and ChemCam observations of K-rich rocks elsewhere in Gale Crater. The source of this sediment component was likely volcanic. Finally, the presence of sediment from many igneous sources, in concert with Curiosity's identifications of other igneous materials (e.g., mugearite), implies that the northern rim of Gale Crater exposes a diverse igneous complex, at least as diverse as that found in similar-age terranes on Earth.« less
  • Relative reflectace point spectra (400–840 nm) were acquired by the Chemistry and Camera (ChemCam) instrument on the Mars Science Laboratory (MSL) rover Curiosity in passive mode (no laser) of drill tailings and broken rock fragments near the rover as it entered the lower reaches of Mt. Sharp and of landforms at distances of 2–8 km. Freshly disturbed surfaces are less subject to the spectral masking effects of dust, and revealed spectral features consistent with the presence of iron oxides and ferric sulfates. Here, we present the first detection on Mars of a ~433 nm absorption band consistent with small abundancesmore » of ferric sulfates, corroborated by jarosite detections by the Chemistry and Mineralogy (CheMin) X-ray diffraction instrument in the Mojave, Telegraph Peak, and Confidence Hills drilled samples. The disturbed materials near the Bonanza King region also exhibited strong 433 nm bands and negative near-infrared spectral slopes consistent with jarosite. ChemCam passive spectra of the Confidence Hills and Mojave drill tailings showed features suggestive of the crystalline hematite identified by CheMin analyses. The Windjana drill sample tailings exhibited flat, low relative reflectance spectra, explained by the occurrence of magnetite detected by CheMin. Passive spectra of Bonanza King were similar, suggesting the presence of spectrally dark and neutral minerals such as magnetite. Long-distance spectra of the “Hematite Ridge” feature (3–5 km from the rover) exhibited features consistent with crystalline hematite. The Bagnold dune field north of the Hematite Ridge area exhibited low relative reflectance and near-infrared features indicative of basaltic materials (olivine, pyroxene). Light-toned layers south of Hematite Ridge lacked distinct spectral features in the 400–840 nm region, and may represent portions of nearby clay minerals and sulfates mapped with orbital near-infrared observations. The presence of ferric sulfates such as jarosite in the drill tailings suggests a relatively acidic environment, likely associated with flow of iron-bearing fluids, associated oxidation, and/or hydrothermal leaching of sedimentary rocks. Combined with other remote sensing data sets, mineralogical constraints from ChemCam passive spectra will continue to play an important role in interpreting the mineralogy and composition of materials encountered as Curiosity traverses further south within the basal layers of the Mt. Sharp complex.« less
  • The Curiosity rover conducted the first field investigation of an active extraterrestrial dune. Our study of the Bagnold dunes focuses on the ChemCam chemical results and also presents findings on the grain size distributions based on the ChemCam RMI and MAHLI images. These active dunes are composed of grains that are mostly <250 μm. Their composition is overall similar to that of the aeolian deposits analyzed all along the traverse (“Aeolis Palus soils”). Nevertheless, the dunes contain less volatiles (Cl, H, S) than the Aeolis Palus soils, which appears to be due to a lower content of volatile-rich fine-grained particlesmore » (<100 μm), or a lower content of volatile-rich amorphous component, possibly as a result of: 1) a lower level of chemical alteration; 2) the removal of an alteration rind at the surface of the grains during transport; 3) a lower degree of interaction with volcanic gases/aerosols; or 4) physical sorting that removed the smallest and most altered grains. Analyses of the >150 μm grain-size dump piles have shown that coarser grains (150-250 μm) are enriched in the mafic elements Fe and Mn, suggesting a larger content in olivine compared to smaller grains (<150 μm) of the Bagnold dunes. Furthermore, the chemistry of soils analyzed in the vicinity of the dunes indicates that they are similar to the dune material. Altogether these observations suggest that the olivine content determined by X-ray diffraction of the <150 μm grain-size sample should be considered as a lower limit for the Bagnold dunes.« less
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