Abstract
Pyroxene minerals are a significant component of Shergottite-Nakhlite-Chassignite (SNC) meteorites (e.g., Velbel 2012) and detected across large areas of Mars’ surface (e.g., Mustard et al. 2005). These minerals are associated with chloride, sulfate, and perchlorate salts that may represent briny waters present in Mars’ history. Previous textural analyses by Velbel and Losiak (2010) comparing pyroxenes and amphiboles from various natural weathering environments showed no correlation between apparent apical angles (describing the morphology of denticular weathering textures) and mineralogy or aqueous alteration history in relatively dilute solutions. However, high-salinity brines preferentially dissolve surface species, potentially leading to different textures dependent on the brine chemistry. In this study, we performed controlled pyroxene dissolution experiments in the laboratory on a well-characterized diopside to determine if aqueous alteration in different high-salinity brines, representative of potential weathering fluids on Mars, produce unique textural signatures.
Following two months of dissolution in batch reactors, we observed denticles on etch pit margins and pyroxene chip boundaries in all of the solutions investigated: ultrapure water (18 MΩ cm−1; aH2O = 1); low-salinity solutions containing 0.35 M NaCl (aH2O = 0.99), 0.35 M Na2SO4 (aH2O = 0.98), and 2 M NaClO4(aH2O = 0.9); and near-saturated brines containing 1.7 M Na2SO4 (aH2O = 0.95), 3 M NaCl (aH2O = 0.75), and 4.5 M CaCl2 (aH2O = 0.35). No systematic change in denticle length or apical angle was observed between any of the solutions investigated, even when altered in brines with significantly different salinity, activity of water, and anion composition. Based on these and previous results from natural systems, apical angle measurements are not a useful proxy for determining the extent or nature of aqueous alteration. However, since denticles form relatively slowly during weathering at circum-neutral pH, denticle length may be a useful proxy for chemical weathering duration. All of the experimental solutions produced median denticle lengths ≤ 1 µm, likely due to the brief weathering experiments. However, perchlorate brines produced a significantly wider range of denticle lengths than those observed in all the other experimental solutions tested. Since perchlorate is likely a common constituent in martian soils (Glotch et al. 2016), denticle length measurements should be used cautiously as proxies for extent of aqueous alteration on Mars, particularly in samples that also contain perchlorate.
Acknowledgments
This study was supported by a NASA Mars Fundamental Research Grant NNX-13AG75G. We gratefully acknowledge the assistance of Preston Larson of OU’s Sam Noble Microscopy Laboratory and George Morgan of OU’s Electron Microprobe Laboratory for their analytical assistance. We are grateful for three reviews, including those of M.A. Velbel and S. Andò that led to substantial improvements.
References cited
Andó, S., Garzanti, E., Padoan, M., and Limonta, M. (2012) Corrosion of heavy minerals during weathering and diagenesis: A catalog for optical analysis. Sedimentary Geology, 280, 165–178.10.1016/j.sedgeo.2012.03.023Search in Google Scholar
Argast, S. (1991) Chlorite vermiculitization and pyroxene etching in an aeolian periglacial sand dune, Allen County, Indiana. Clays and Clay Minerals, 39(6), 622–633.10.1346/CCMN.1991.0390608Search in Google Scholar
Bandfield, J.L., Hamilton, V.E., and Christensen, P.R. (2000) A global view of Martian surface compositions from MGS-TES. Science, 287, 1626–1630.10.1126/science.287.5458.1626Search in Google Scholar
Behrens, R., Bouchez, J., Schuessler, J.A., Dultz, S., Hewawasam, T., and von Blanckenburg, F. (2015) Mineralogical transformations set slow weathering rates in low-porosity metamorphic bedrock on mountain slopes in a tropical climate. Chemical Geology, 411, 283–298.10.1016/j.chemgeo.2015.07.008Search in Google Scholar
Benzerara, K., Yoon, T., Menguy, N., Tyliszczak, T., and Brown, G. (2005) Nanoscale environments associated with bioweathering of a Mg-Fe-pyroxene. Proceedings of the National Academy of Sciences, 102, 979–982.10.1073/pnas.0409029102Search in Google Scholar
Berner, R.A. (1978) Rate control of mineral dissolution under earth surface conditions. American Journal of Science, 278(9), 1235–1252.10.2475/ajs.278.9.1235Search in Google Scholar
Berner, R.A., and Schott, J. (1982) Mechanism of pyroxene and amphibole weathering; II, Observations of soil grains. American Journal of Science, 282(8), 1214–1231.10.2475/ajs.282.8.1214Search in Google Scholar
Berner, R.A., Sjöberg, E.L., Velbel, M.A., and Krom, M.D. (1980) Dissolution of pyroxenes and amphiboles during weathering. Science, 207, 1205–1206.10.1126/science.207.4436.1205Search in Google Scholar
Brantley, S.L., and Chen, Y. (1995) Chemical weathering rates of pyroxenes and amphiboles. Reviews in Mineralogy and Geochemistry, 31, 119–172.Search in Google Scholar
Brantley, S.L., Crane, S.R., Crerar, D.A., Hellmann, R., and Stallard, R. (1986) Dissolution at dislocation etch pits in quartz. Geochimica et Cosmochimica Acta, 50(10), 2349–2361.10.1016/0016-7037(86)90087-6Search in Google Scholar
Brantley, S.L., Blai, A.C., Cremeens, D.L., MacInnis, I., and Darmody, R.G. (1993) Natural etching rates of feldspar and hornblende. Aquatic Sciences, 55(4), 262–272.10.1007/BF00877271Search in Google Scholar
Bridges, J.C., and Grady, M.M. (1999) A halite-siderite-anhydrite-chlorapatite assemblage in Nakhla: Mineralogical evidence for evaporites on Mars. Meteoritics and Planetary Science, 34, 407–415.10.1111/j.1945-5100.1999.tb01349.xSearch in Google Scholar
Bridges, J.C., and Grady, M.M. (2000) Evaporite mineral assemblages in the nakhlite (martian) meteorites. Earth and Planetary Science Letters, 176(3), 267–279.10.1016/S0012-821X(00)00019-4Search in Google Scholar
Bridges, J.C., Catling, D.C., Saxton, J.M., Swindle, T.D., Lyon, I.C., and Grady, M.M. (2001) Alteration assemblages in Martian meteorites: Implications for near-surface processes. In R. Kallenbach, J. Geiss, and W.K. Hartmann, Eds., Chronology and Evolution of Mars, p. 365–392. Springer, Netherlands.10.1007/978-94-017-1035-0_13Search in Google Scholar
Brown, G.E. Jr., and Parks, G.A. (2001) Sorption of trace elements on mineral surfaces: modern perspectives from spectroscopic studies, and comments on sorption in the marine environment. International Geology Review, 43(11), 963–1073.10.1080/00206810109465060Search in Google Scholar
Burns, R.G. (1993) Rates and mechanisms of chemical weathering of ferromagnesian silicate minerals on Mars. Geochimica et Cosmochimica Acta, 57, 4555–4574.10.1016/0016-7037(93)90182-VSearch in Google Scholar
Chatzitheodoridis, E., and Turner, G. (1990) Secondary minerals in the Nakhla meteorite. Meteoritics, 25, 354–354.Search in Google Scholar
Chen, Y., and Brantley, S.L. (1998) Diopside and anthophyllite dissolution at 25 and 90 °C and acid pH. Chemical Geology, 147(3), 233–248.10.1016/S0009-2541(98)00016-3Search in Google Scholar
Chevrier, V.F., Hanley, J., and Altheide, T.S. (2009) Stability of perchlorate hydrates and their liquid solutions at the Phoenix landing site, Mars. Geophysical Research Letters, 36(10), L10202.10.1029/2009GL037497Search in Google Scholar
Cremeens, D.L., Darmody, R.G., and Norton, L.D. (1992) Etch-pit size and shape distribution on orthoclase and pyriboles in a loess catena. Geochimica et Cosmochimica Acta, 56(9), 3423–3434.10.1016/0016-7037(92)90389-ZSearch in Google Scholar
Elwood Madden, M.E., Madden, A.S., Rimstidt, J.D., Zahrai, S., Kendall, M.R., and Miller, M.A. (2012) Jarosite dissolution rates and nanoscale mineralogy. Geochimica et Cosmochimica Acta, 91, 306–321.10.1016/j.gca.2012.05.001Search in Google Scholar
Glavin, D.P., Freissinet, C., Miller, K.E., Eigenbrode, J.L., Brunner, A.E., Buch, A., Sutter, B., Archer, P.D., Atreya, S.K., Brinckerhoff, W.B., and Cabane, M. (2013) Evidence for perchlorates and the origin of chlorinated hydrocarbons detected by SAM at the Rocknest aeolian deposit in Gale Crater. Journal of Geophysical Research: Planets, 118(10), 1955–1973.10.1002/jgre.20144Search in Google Scholar
Glotch, T., Bandfield, J., Wolff, M., Arnold, J., and Che, C. (2016) Constraints on the composition and particle size of chloride salt-bearing deposits on Mars. Journal of Geophysical Research: Planets, 121, 454–471.10.1002/2015JE004921Search in Google Scholar
Gooding, J.L., Wentworth, S.J., and Zolensky, M.E. (1988) Calcium carbonate and sulfate of possible extraterrestrial origin in the EETA 79001 meteorite. Geochimica et Cosmochimica Acta, 52(4), 909–915.10.1016/0016-7037(88)90361-4Search in Google Scholar
Gooding, J.L., Wentworth, S.J., and Zolensky, M.E. (1991) Aqueous alteration of the Nakhla meteorite. Meteoritics and Planetary Science, 26(2), 135–143.10.1111/j.1945-5100.1991.tb01029.xSearch in Google Scholar
Hall, R.D., and Horn, L.L. (1993) Rates of hornblende etching in soils in glacial deposits of the northern Rocky Mountains (Wyoming-Montana, USA): Influence of climate and characteristics of the parent material. Chemical Geology, 105(1-3), 17–29.10.1016/0009-2541(93)90116-ZSearch in Google Scholar
Hall, R.D., and Michaud, D. (1988) The use of hornblende etching, clast weathering, and soils to date alpine glacial and periglacial deposits: a study from southwestern Montana. Geological Society of America Bulletin, 100(3), 458–467.10.1130/0016-7606(1988)100<0458:TUOHEC>2.3.CO;2Search in Google Scholar
Hecht, M.H., Kounaves, S.P., Quinn, R.C., West, S.J., Young, S.M.M., Ming, D.W., Catling, D.C., Clark, B.C., Boynton, W.V., Hoffman, J., and DeFlores, L.P. (2009) Detection of perchlorate and the soluble chemistry of martian soil at the Phoenix lander site. Science, 325, 64–67.10.1126/science.1172466Search in Google Scholar
Hoch, A.R., Reddy, M.M., and Drever, J.I. (1996) The effect of iron content and dissolved O2 on dissolution rates of clinopyroxene at pH 5.8 and 25°C: preliminary results. Chemical Geology, 132, 151–156.10.1016/S0009-2541(96)00050-2Search in Google Scholar
Hochella, M.F., and Banfield, J.F. (1995) Chemical weathering of silicates in nature; a microscopic perspective with theoretical considerations. Reviews in Mineralogy and Geochemistry, 31, 353–406.10.1515/9781501509650-010Search in Google Scholar
Hodson, M.E. (2003) The influence of Fe-rich coatings on the dissolution of anorthite at pH 2.6. Geochimica et Cosmochimica Acta, 67, 3355–3363.10.1016/S0016-7037(02)01370-4Search in Google Scholar
Kounaves, S.P., Carrier, B.L., O’Neil, G.D., Stroble, S.T., and Claire, M.W. (2014) Evidence of martian perchlorate, chlorate, and nitrate in Mars meteorite EETA79001: Implications for oxidants and organics. Icarus, 229, 206–213.10.1016/j.icarus.2013.11.012Search in Google Scholar
Lee, M.R., Brown, D.J., Hodson, M.E., MacKenzie, M., and Smith, C.L. (2008) Weathering microenvironments on feldspar surfaces: implications for understanding fluid-mineral reactions in soils. Mineralogical Magazine, 72, 1319–1328.10.1180/minmag.2008.072.6.1319Search in Google Scholar
Lee, M.R., Tomkinson, T., Mark, D.F., Stuart, F.M., and Smith, C.L. (2013) Evidence for silicate dissolution on Mars from the Nakhla meteorite. Meteoritics and Planetary Science, 48(2), 224–240.10.1111/maps.12053Search in Google Scholar
Legett, C., Pritchett, B.N., Elwood Madden, A.S., and Elwood Madden, M.E. (2014) Measuring mineral dissolution rates in perchlorate brines: Method development and applications. Lunar and Planetary Sciences Conference, p. 2492.Search in Google Scholar
Ling, Z., and Wang, A. (2015) Spatial distributions of secondary minerals in the Martian meteorite MIL 03346, 168 determined by Raman spectroscopic imaging. Journal of Geophysical Research: Planets, 120(6), 1141–1159.10.1002/2015JE004805Search in Google Scholar
MacInnis, I.N., and Brantley, S.L. (1993) Development of etch pit size distributions on dissolving minerals. Chemical Geology, 105(1-3), 31–49.10.1016/0009-2541(93)90117-2Search in Google Scholar
McSween, H.Y. (1994) What we have learned about Mars from SNC meteorites. Meteoritics, 29(6), 757–779.10.1111/j.1945-5100.1994.tb01092.xSearch in Google Scholar
Mikesell, L.R., Schaetzl, R.J., and Velbel, M.A. (2004) Hornblende etching and quartz/ feldspar ratios as weathering and soil development indicators in some Michigan soils. Quaternary Research, 62(2), 162–171.10.1016/j.yqres.2004.06.006Search in Google Scholar
Miller, J.L., Madden, A.E., Phillips-Lander, C.M., Pritchett, B.N., and Madden, M.E. (2016) Alunite dissolution rates: Dissolution mechanisms and implications for Mars. Geochimica et Cosmochimica Acta, 172, 93–106.10.1016/j.gca.2015.10.001Search in Google Scholar
Mustard, J.F., Poulet, F., Gendrin, A., Bibring, J.-P., Langevin, Y., Gondet, B., Mangold, N., Bellucci, G., and Altieri, F. (2005) Olivine and pyroxene diversity in the crust of Mars. Science, 307, 1594–1597.10.1126/science.1109098Search in Google Scholar PubMed
Navarro-González, R., Vargas, E., de La Rosa, J., Raga, A.C., and McKay, C.P. (2010) Reanalysis of the Viking results suggests perchlorate and organics at midlatitudes on Mars. Journal of Geophysical Research, 115, E12010.10.1029/2010JE003599Search in Google Scholar
Ojha, L., Wilhelm, M.B., Murchie, S.L., McEwen, A.S., Wray, J.J., Hanley, J., Massé, M., and Chojnacki, M. (2015) Spectral evidence for hydrated salts in recurring slope lineae on Mars. Nature Geoscience, 8(11), 829–832.10.1038/ngeo2546Search in Google Scholar
Olsen, A.A., and Rimstidt, J.D. (2008) Oxalate-promoted forsterite dissolution at low pH. Geochimica et Cosmochimica Acta, 72(7), 1758–1766.10.1016/j.gca.2007.12.026Search in Google Scholar
Olsen, A.A., Hausrath, E.M., and Rimstidt, J.D. (2015) Forsterite dissolution rates in Mg-sulfate-rich Mars-analog brines and implications of the aqueous history of Mars. Journal of Geophysical Research: Planets, 120(3), 388–400.10.1002/2014JE004664Search in Google Scholar
Parnell, S.P., Phillips-Lander, C.M., McGraw, L.E., and Elwood Madden, M.E. (2016) Carbonate dissolution rates in high salinity brines. Lunar and Planetary Sciences, 1460.Search in Google Scholar
Phillips-Lander, C.M., Fowle, D.A., Taunton, A., Hernandez, W., Mora, M., Moore, D., Shinogle, H., and Roberts, J.A. (2014) Silicate dissolution in Las Pailas thermal field: Implications for microbial weathering in acidic volcanic hydrothermal spring systems. Geomicrobiology Journal, 31(1), 23–41.10.1080/01490451.2013.802395Search in Google Scholar
Phillips-Lander, C.M., Legett, C. IV, Elwood Madden, A.S., and Elwood Madden, M.E. (2016) Pyroxene dissolution rates in high salinity brines: Implications for post-Noachian aqueous alteration on Mars. 47th Lunar and Planetary Science Conference, Contribution no. 1903, p. 1313.Search in Google Scholar
Pritchett, B.N., Madden, M.E., and Madden, A.S. (2012) Jarosite dissolution rates and maximum lifetimes in high salinity brines: Implications for Earth and Mars. Earth and Planetary Science Letters, 357, 327–336.10.1016/j.epsl.2012.09.011Search in Google Scholar
Sanemasa, I., and Katsura, T. (1973) The dissolution of CaMg(SiO3)2 in acid solutions. Bulletin of the Chemical Society of Japan, 46(11), 3416–3422.10.1246/bcsj.46.3416Search in Google Scholar
Schaetzl, R.J., Mikesell, L.R., and Velbel, M.A. (2006) Soil characteristics related to weathering and pedogenesis across a geomorphic surface of uniform age in Michigan. Physical Geography, 27(2), 170–188.10.2747/0272-3646.27.2.170Search in Google Scholar
Schneider, C.A., Rasband, W.S., and Eliceiri, K.W. (2012) NIH Image to ImageJ: 25 years of image analysis. Nature Methods, 9, 671–675.10.1038/nmeth.2089Search in Google Scholar
Schott, J., and Berner, R. (1983) X-ray photoelectron studies of the mechanism of iron silicate dissolution during weathering. Geochimica et Cosmochimica Acta, 47, 2233–2240.10.1016/0016-7037(83)90046-7Search in Google Scholar
Sidhu, P.S., Gilkes, R.J., Cornell, R.M., Posner, A.M., and Quirk, J.P. (1981) Dissolution of iron oxides and oxyhydroxides in hydrochloric and perchloric acids. Clays and Clay Minerals, 29, 269–276.10.1346/CCMN.1981.0290404Search in Google Scholar
Siever, R., and Woodford, N. (1979) Dissolution kinetics and the weathering of mafic minerals. Geochimica et Cosmochimica Acta, 43, 717–724.10.1016/0016-7037(79)90255-2Search in Google Scholar
Stieglitz, R.D., and Rothwell, B. (1978) Surface microtextures of freshwater heavy mineral grains. Geoscience Wisconsin, 3, 21–34.Search in Google Scholar
Steiner, M.H., Hausrath, E.M., Madden, M.E., Tschauner, O., Ehlmann, B.L., Olsen, A.A., Gainey, S.R., and Smith, J.S. (2016) Dissolution of nontronite in chloride brines and implications for the aqueous history of Mars. Geochimica et Cosmochimica Acta, 195, 259–276.10.1016/j.gca.2016.08.035Search in Google Scholar
Thomas-Keprta, K.L., Clemett, S.J., McKay, D.S., Gibson, E.K., and Wentworth, S.J. (2009) Origins of magnetite nanocrystals in Martian meteorite ALH84001. Geochimica et Cosmochimica Acta, 73, 6631–6677.10.1016/j.gca.2009.05.064Search in Google Scholar
Treiman, A.H. (2005) The nakhlite meteorites: Augite-rich igneous rocks from Mars. Chemie der Erde-Geochemistry, 65(3), 203–270.10.1016/j.chemer.2005.01.004Search in Google Scholar
Treiman, A.H., Barrett, R.A., and Gooding, J.L. (1993) Preterrestrial aqueous alteration of the Lafayette (SNC) meteorite. Meteoritics, 28(1), 86–97.10.1111/j.1945-5100.1993.tb00251.xSearch in Google Scholar
Velbel, M.A. (1993) Formation of protective surface layers during silicate-mineral weathering under well-leached, oxidizing conditions. American Mineralogist, 78, 405–405.Search in Google Scholar
Velbel, M.A. (2007) Surface textures and dissolution processes of heavy minerals in the sedimentary cycle: examples from pyroxenes and amphiboles. Developments in Sedimentology, 58, 113–150.10.1016/S0070-4571(07)58004-0Search in Google Scholar
Velbel, M.A. (2011) Microdenticles on naturally weathered hornblende. Applied Geochemistry, 26(8), 1594–1596.10.1016/j.apgeochem.2011.05.008Search in Google Scholar
Velbel, M.A. (2012) Aqueous alteration in Martian meteorites: Comparing mineral relations in igneous-rock weathering of Martian meteorites and in the sedimentary cycle of Mars. Sedimentary Geology of Mars, SEPM. Society for Sedimentary Geology Special Publication, 102, 97–117.Search in Google Scholar
Velbel, M.A. (2014) Terrestrial weathering of ordinary chondrites in nature and continuing during laboratory storage and processing: Review and implications for Hayabusa sample integrity. Meteoritics & Planetary Science, 49(2), 154–171.10.1111/j.1945-5100.2012.01405.xSearch in Google Scholar
Velbel, M.A. (2016) Aqueous corrosion of olivine in the Mars meteorite Miller Range (MIL) 03346 during Antarctic weathering: Implications for water on Mars. Geochimica et Cosmochimica Acta, 180, 126–145.10.1016/j.gca.2016.01.036Search in Google Scholar
Velbel, M.A., and Barker, W.W. (2008) Pyroxene weathering to smectite: conventional and cryo-field emission scanning electron microscopy, Koua Bocca ultramafic complex, Ivory Coast. Clays and Clay Minerals, 56(1), 112–127.10.1346/CCMN.2008.0560110Search in Google Scholar
Velbel, M.A., and Losiak, A.I. (2010) Denticles on chain silicate grain surfaces and their utility as indicators of weathering conditions on Earth and Mars. Journal of Sedimentary Research, 80(9), 771–780.10.2110/jsr.2010.074Search in Google Scholar
Wentworth, S.J., and Gooding, J.L. (1994) Carbonates and sulfates in the Chassigny meteorite: Further evidence for aqueous chemistry on the SNC parent planet. Meteoritics, 29(6), 860–863.10.1111/j.1945-5100.1994.tb01100.xSearch in Google Scholar
Werner, A.J., Hochella, M.F., Guthrie, G.D., Hardy, J.A., and Aust, A.E. (1995) Asbestiform riebeckite (crocidolite) dissolution in the presence of Fe chelators: implications for mineral-induced disease. American Mineralogist, 80(11-12), 1093–1103.10.2138/am-1995-11-1201Search in Google Scholar
White, A.F., and Brantley, S.L. (2003) The effect of time on the weathering of silicate minerals: why do weathering rates differ in the laboratory and field? Chemical Geology, 202(3), 479–506.10.1016/j.chemgeo.2003.03.001Search in Google Scholar
White, A., Yee, A., and Flexser, S. (1985) Surface oxidation-reduction kinetics associated with experimental basalt-water reaction at 25°C. Chemical Geology, 49, 73–86.10.1016/0009-2541(85)90148-2Search in Google Scholar
© 2017 by Walter de Gruyter Berlin/Boston