Tardi-magmatic precipitation of Martian Fe/Mg-rich clay minerals via igneous differentiation
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Keywords: Mars, magmatic precipitation, clay minerals
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 Figure 1 SEM images of the investigated thin section of Nakhla in BSE mode. (a) BSE image of the augite cumulate texture of Nakhla. (b,c) BSE image of the Nakhla mesostasis (b) and corresponding EDXS-based mineralogical map (c). (d–f) BSE images of the tardi-magmatic Fe/Mg-rich clay minerals observed in the mesostasis of Nakhla in contact with Na/Ca-plagioclase, K-feldspar, quartz and Cl-apatite. |  Figure 2 TEM images of the FIB sections extracted from the mesostasis of Nakhla in STEM mode. (a–e). Images of the magmatic Fe/Mg-rich clay minerals minerals observed in the mesostasis of Nakhla in contact with K-feldspar, quartz, Cl-apatite and in inclusions within K-feldspar. |  Figure 3 Sketch summarising the crystallisation sequence of the mesostasis of Nakhla. (a) Crystallisation of augite and entrapment of a fraction of the residual melt. (b) Crystallisation of Fe-rich rims of augite. (c) Crystallisation of Na/Ca-plagioclase and Fe/Ti-oxides. (d) Crystallisation of K-feldspars, Cl-apatite and quartz. (e) Precipitation of Cl-rich Fe/Mg-clay minerals. |
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Letter
Recent discoveries have provided direct evidence that chemically evolved rocks formed over short timescales on planetesimals early in the Solar System (Day et al., 2009
Day, J.M.D., Ash, R.D., Liu, Y., Bellucci, J.J., III, D.R., McDonough, W.F., Walker, R.J., Taylor, L.A. (2009) Early formation of evolved asteroidal crust. Nature 457, 179–182.
; Bischoff et al., 2014Bischoff, A., Horstmann, M., Barrat, J.-A., Chaussidon, M., Pack, A., Herwartz, D., Ward, D., Vollmer, C., Decker, S. (2014) Trachyandesitic volcanism in the early Solar System. Proceedings of the National Academy of Sciences 111, 12689.
; Frossard et al., 2019Frossard, P., Boyet, M., Bouvier, A., Hammouda, T., Monteux, J. (2019) Evidence for anorthositic crust formed on an inner solar system planetesimal. Geochemical Perspectives Letters 11, 28–32.
). However, it is unclear if and how much such evolved rocks contributed to the ancient crust of Mars (Sautter et al., 2015Sautter, V., Toplis, M.J., Wiens, R.C., Cousin, A., Fabre, C., Gasnault, O., Maurice, S., Forni, O., Lasue, J., Ollila, A., Bridges, J.C., Mangold, N., Le Mouélic, S., Fisk, M., Meslin, P.-Y., Beck, P., Pinet, P., Le Deit, L., Rapin, W., Stolper, E.M., Newsom, H., Dyar, D., Lanza, N., Vaniman, D., Clegg, S., Wray, J.J. (2015) In situ evidence for continental crust on early Mars. Nature Geoscience 8, 605.
, 2016Sautter, V., Toplis, M.J., Beck, P., Mangold, N., Wiens, R., Pinet, P., Cousin, A., Maurice, S., LeDeit, L., Hewins, R., Gasnault, O., Quantin, C., Forni, O., Newsom, H., Meslin, P.-Y., Wray, J., Bridges, N., Payre, V., Rapin, W., Le Mouelic, S. (2016) Magmatic complexity on early Mars as seen through a combination of orbital, in-situ and meteorite data. Lithos 254, 36–52.
; Udry et al., 2018Udry, A., Gazel, E., McSween Jr., H.Y. (2018) Formation of Evolved Rocks at Gale Crater by Crystal Fractionation and Implications for Mars Crustal Composition. Journal of Geophysical Research: Planets 123, 1525–1540.
; Bouley et al., 2020Bouley, S., Keane, J.T., Baratoux, D., Langlais, B., Matsuyama, I., Costard, F., Hewins, R., Payré, V., Sautter, V., Séjourné, A. et al. (2020) A thick crustal block revealed by reconstructions of early Mars highlands. Nature Geoscience 13, 105–109.
).Only rare exposures of evolved rocks containing hydrated silica and/or quartz have been reported from orbit (Christensen et al., 2005
Christensen, P.R., McSween, H.Y., Bandfield, J.L., Ruff, S.W., Rogers, A.D., Hamilton, V.E., Gorelick, N., Wyatt, M.B., Jakosky, B.M., Kieffer, H.H., Malin, M.C., Moersch, J.E. (2005) Evidence for magmatic evolution and diversity on Mars from infrared observations. Nature 436, 504–509.
; Bandfield, 2006Bandfield, J.L. (2006) Extended surface exposures of granitoid compositions in Syrtis Major, Mars. Geophysical Research Letters 33, L06203.
; Carter and Poulet, 2013Carter, J., Poulet, F. (2013) Ancient plutonic processes on Mars inferred from the detection of possible anorthositic terrains. Nature Geoscience 6, 1008.
; Wray et al., 2013Wray, J.J., Hansen, S.T., Dufek, J., Swayze, G.A., Murchie, S.L., Seelos, F.P., Skok, J.R., Irwin III, R.P., Ghiorso, M.S. (2013) Prolonged magmatic activity on Mars inferred from the detection of felsic rocks. Nature Geoscience 6, 1013.
). In addition to the small depth analysed, that makes dust and coatings dominate the signal, difficulties pertain to the spectral featureless of the main constituents of evolved rocks (e.g., feldspar and quartz), leading to some much discussed ambiguities (Smith and Bandfield, 2012Smith, M.R., Bandfield, J.L. (2012) Geology of quartz and hydrated silica-bearing deposits near Antoniadi Crater, Mars. Journal of Geophysical Research: Planets 117, E06007.
; Ehlmann and Edwards, 2014Ehlmann, B.L., Edwards, C.S. (2014) Mineralogy of the Martian Surface. Annual Review of Earth and Planetary Sciences 42, 291–315.
; Rogers and Nekvasil, 2015Rogers, A.D., Nekvasil, H. (2015) Feldspathic rocks on Mars: Compositional constraints from infrared spectroscopy and possible formation mechanisms. Geophysical Research Letters 42, 2619–2626.
). Because of the presence of Fe/Mg-rich clay minerals interpreted as secondary aqueous alteration products (Gooding et al., 1991Gooding, J.L., Wentworth, S.J., Zolensky, M.E. (1991) Aqueous alteration of the Nakhla meteorite. Meteoritics 26, 135–143.
; Bridges et al., 2001Bridges, J.C., Catling, D.C., Saxton, J.M., Swindle, T.D., Lyon, I.C., Grady, M.M. (2001) Alteration Assemblages in Martian Meteorites: Implications for Near-Surface Processes. Space Science Reviews 96, 365–392.
; Carter and Poulet, 2013Carter, J., Poulet, F. (2013) Ancient plutonic processes on Mars inferred from the detection of possible anorthositic terrains. Nature Geoscience 6, 1008.
; Wray et al., 2013Wray, J.J., Hansen, S.T., Dufek, J., Swayze, G.A., Murchie, S.L., Seelos, F.P., Skok, J.R., Irwin III, R.P., Ghiorso, M.S. (2013) Prolonged magmatic activity on Mars inferred from the detection of felsic rocks. Nature Geoscience 6, 1013.
; Hicks et al., 2014Hicks, L.J., Bridges, J.C., Gurman, S.J. (2014) Ferric saponite and serpentine in the nakhlite martian meteorites. Geochimica et Cosmochimica Acta 136, 194–210.
), the rare evolved rocks detected from orbit have been interpreted as resulting from the hydrothermal alteration or diagenesis of mafic crustal materials (Smith and Bandfield, 2012Smith, M.R., Bandfield, J.L. (2012) Geology of quartz and hydrated silica-bearing deposits near Antoniadi Crater, Mars. Journal of Geophysical Research: Planets 117, E06007.
; Ehlmann and Edwards, 2014Ehlmann, B.L., Edwards, C.S. (2014) Mineralogy of the Martian Surface. Annual Review of Earth and Planetary Sciences 42, 291–315.
).Yet, robotic missions evidenced that igneous differentiation induced by fractional crystallisation occurred on Mars (McSween et al., 1999
McSween, H.Y., Murchie, S.L., Crisp, J.A., Bridges, N.T., Anderson, R.C., Bell III, J.F., Britt, D.T., Brückner, J., Dreibus, G., Economou, T., Ghosh, A., Golombek, M.P., Greenwood, J.P., Johnson, J.R., Moore, H.J., Morris, R.V., Parker, T.J., Rieder, R., Singer, R., Wänke, H. (1999) Chemical, multispectral, and textural constraints on the composition and origin of rocks at the Mars Pathfinder landing site. Journal of Geophysical Research: Planets 104, 8679–8715.
, 2006McSween, H.Y., Ruff, S.W., Morris, R.V., Bell III, J.F., Herkenhoff, K., Gellert, R., Stockstill, K.R., Tornabene, L.L., Squyres, S.W., Crisp, J.A., Christensen, P.R., McCoy, T.J., Mittlefehldt, D.W., Schmidt, M. (2006) Alkaline volcanic rocks from the Columbia Hills, Gusev crater, Mars. Journal of Geophysical Research: Planets 111.
; Stolper et al., 2013Stolper, E.M., Baker, M.B., Newcombe, M.E., Schmidt, M.E., Treiman, A.H., Cousin, A., Dyar, M.D., Fisk, M.R., Gellert, R., King, P.L., Leshin, L., Maurice, S., McLennan, S.M., Minitti, M.E., Perrett, G., Rowland, S., Sautter, V., Wiens, R.C. (2013) The Petrochemistry of Jake_M: A Martian Mugearite. Science 341, 1239463.
; Sautter et al., 2015Sautter, V., Toplis, M.J., Wiens, R.C., Cousin, A., Fabre, C., Gasnault, O., Maurice, S., Forni, O., Lasue, J., Ollila, A., Bridges, J.C., Mangold, N., Le Mouélic, S., Fisk, M., Meslin, P.-Y., Beck, P., Pinet, P., Le Deit, L., Rapin, W., Stolper, E.M., Newsom, H., Dyar, D., Lanza, N., Vaniman, D., Clegg, S., Wray, J.J. (2015) In situ evidence for continental crust on early Mars. Nature Geoscience 8, 605.
, 2016Sautter, V., Toplis, M.J., Beck, P., Mangold, N., Wiens, R., Pinet, P., Cousin, A., Maurice, S., LeDeit, L., Hewins, R., Gasnault, O., Quantin, C., Forni, O., Newsom, H., Meslin, P.-Y., Wray, J., Bridges, N., Payre, V., Rapin, W., Le Mouelic, S. (2016) Magmatic complexity on early Mars as seen through a combination of orbital, in-situ and meteorite data. Lithos 254, 36–52.
; Udry et al., 2018Udry, A., Gazel, E., McSween Jr., H.Y. (2018) Formation of Evolved Rocks at Gale Crater by Crystal Fractionation and Implications for Mars Crustal Composition. Journal of Geophysical Research: Planets 123, 1525–1540.
). The Spirit rover encountered alkaline volcanic rocks, substantially enriched in Na/K-rich plagioclase relative to pyroxene and olivine (McSween et al., 2006McSween, H.Y., Ruff, S.W., Morris, R.V., Bell III, J.F., Herkenhoff, K., Gellert, R., Stockstill, K.R., Tornabene, L.L., Squyres, S.W., Crisp, J.A., Christensen, P.R., McCoy, T.J., Mittlefehldt, D.W., Schmidt, M. (2006) Alkaline volcanic rocks from the Columbia Hills, Gusev crater, Mars. Journal of Geophysical Research: Planets 111.
), while Curiosity found both fine grained alkali basalts known as mugearites (Stolper et al., 2013Stolper, E.M., Baker, M.B., Newcombe, M.E., Schmidt, M.E., Treiman, A.H., Cousin, A., Dyar, M.D., Fisk, M.R., Gellert, R., King, P.L., Leshin, L., Maurice, S., McLennan, S.M., Minitti, M.E., Perrett, G., Rowland, S., Sautter, V., Wiens, R.C. (2013) The Petrochemistry of Jake_M: A Martian Mugearite. Science 341, 1239463.
) and coarse grained alkali feldspar-bearing lithologies (Sautter et al., 2015Sautter, V., Toplis, M.J., Wiens, R.C., Cousin, A., Fabre, C., Gasnault, O., Maurice, S., Forni, O., Lasue, J., Ollila, A., Bridges, J.C., Mangold, N., Le Mouélic, S., Fisk, M., Meslin, P.-Y., Beck, P., Pinet, P., Le Deit, L., Rapin, W., Stolper, E.M., Newsom, H., Dyar, D., Lanza, N., Vaniman, D., Clegg, S., Wray, J.J. (2015) In situ evidence for continental crust on early Mars. Nature Geoscience 8, 605.
, 2016Sautter, V., Toplis, M.J., Beck, P., Mangold, N., Wiens, R., Pinet, P., Cousin, A., Maurice, S., LeDeit, L., Hewins, R., Gasnault, O., Quantin, C., Forni, O., Newsom, H., Meslin, P.-Y., Wray, J., Bridges, N., Payre, V., Rapin, W., Le Mouelic, S. (2016) Magmatic complexity on early Mars as seen through a combination of orbital, in-situ and meteorite data. Lithos 254, 36–52.
; Udry et al., 2018Udry, A., Gazel, E., McSween Jr., H.Y. (2018) Formation of Evolved Rocks at Gale Crater by Crystal Fractionation and Implications for Mars Crustal Composition. Journal of Geophysical Research: Planets 123, 1525–1540.
). Consistently monzonitic clasts have been found in Black Beauty (Humayun et al., 2013Humayun, M., Nemchin, A., Zanda, B., Hewins, R.H., Grange, M., Kennedy, A., Lorand, J.-P., Göpel, C., Fieni, C., Pont, S., Deldicque, D. (2013) Origin and age of the earliest Martian crust from meteorite NWA 7533. Nature 503, 513–516.
; Hewins et al., 2017Hewins, R.H., Zanda, B., Humayun, M., Nemchin, A., Lorand, J.-P., Pont, S., Deldicque, D., Bellucci, J.J., Beck, P., Leroux, H., Marinova, M., Remusat, L., Göpel, C., Lewin, E., Grange, M., Kennedy, A., Whitehouse, M.J. (2017) Regolith breccia Northwest Africa 7533: Mineralogy and petrology with implications for early Mars. Meteoritics & Planetary Science 52, 89–124.
), while K-feldspar, SiO2 polymorphs (cristobalite, trydimite and quartz) and even rhyolitic glass have been observed (in addition to apatite and zircon) within nakhlites (Treiman, 2005Treiman, A.H. (2005) The nakhlite meteorites: Augite-rich igneous rocks from Mars. Geochemistry 65, 203–270.
; Nekvasil et al., 2007Nekvasil, H., Filiberto, J., McCubbin, F.M., Lindsley, D.H. (2007) Alkalic parental magmas for chassignites? Meteoritics & Planetary Science 42, 979–992.
; McCubbin et al., 2013McCubbin, F.M., Elardo, S.M., Shearer, C.K., Smirnov, A., Hauri, E.H., Draper, D.S. (2013) A petrogenetic model for the comagmatic origin of chassignites and nakhlites: Inferences from chlorine-rich minerals, petrology, and geochemistry. Meteoritics & Planetary Science 48, 819–853.
; Giesting and Filiberto, 2016Giesting, P.A., Filiberto, J. (2016) The formation environment of potassic-chloro-hastingsite in the nakhlites MIL 03346 and pairs and NWA 5790: Insights from terrestrial chloro-amphibole. Meteoritics & Planetary Science 51, 2127–2153.
).Here we investigate the paragenesis of the evolved mesostasis of Nakhla, the Martian meteorite eponym for nakhlites. Nakhlites are augite cumulates that differ from each other in the proportion and crystallinity of the mesostasis (Treiman, 2005
Treiman, A.H. (2005) The nakhlite meteorites: Augite-rich igneous rocks from Mars. Geochemistry 65, 203–270.
). They were emplaced ∼1.3 Gyr ago as multiple flows, dikes or sills close to the surface (Udry and Day, 2018Udry, A., Day, J.M.D. (2018) 1.34 billion-year-old magmatism on Mars evaluated from the co-genetic nakhlite and chassignite meteorites. Geochimica et Cosmochimica Acta 238, 292–315.
). The consensus is that nakhlites and chassignites sampled different levels of what may have been a single, large igneous complex (McCubbin et al., 2013McCubbin, F.M., Elardo, S.M., Shearer, C.K., Smirnov, A., Hauri, E.H., Draper, D.S. (2013) A petrogenetic model for the comagmatic origin of chassignites and nakhlites: Inferences from chlorine-rich minerals, petrology, and geochemistry. Meteoritics & Planetary Science 48, 819–853.
), with nakhlites having crystallised from the residual melt having first produced chassignites (Udry and Day, 2018Udry, A., Day, J.M.D. (2018) 1.34 billion-year-old magmatism on Mars evaluated from the co-genetic nakhlite and chassignite meteorites. Geochimica et Cosmochimica Acta 238, 292–315.
).Like the other nakhlites, Nakhla exhibits few olivine grains and numerous large crystals of augite that are set in a crystalline mesostasis (Fig. 1). All augite crystals in contact with the mesostasis are zoned, from Mg-rich cores to Fe-rich rims. The mesostasis is mainly composed of Na/Ca-plagioclase laths and euhedral titanomagnetite (Fig. 1). In between the Na/Ca-plagioclase laths, the mesostasis exhibits a vermicular texture consisting of nanoscale Cl-apatite and Fe-sulfides together with quartz, K-feldspar and Fe/Mg-rich clay minerals (Figs. 1, 2). In contrast to iddingsite veins crosscutting olivine in nakhlites (Gooding et al., 1991
Gooding, J.L., Wentworth, S.J., Zolensky, M.E. (1991) Aqueous alteration of the Nakhla meteorite. Meteoritics 26, 135–143.
), these Fe/Mg-rich clay minerals display a high porosity and can be found as masses in contact with or within Na/Ca-plagioclase, Cl-apatite, K-feldspar or quartz (Figs. 1, 2). The clay minerals are made of ∼40 to 100 nm wide lamellar materials, with stacking height ranging from ∼10 to 20 nm and a d-spacing of ∼10 Å (Fig. 2). Their mean structural formula, (K0.22Na0.30Ca0.07(Mg0.93Fe0.58Mn0.05Ti0.02□0.42)(Fe0.93Al0.21Si2.86)(O10)[(OH,O)1.86,Cl0.14]) according to STEM-EDS analyses, falls within the domain of interstratified or mixtures of Cl-rich saponite and celadonite (Meunier et al., 2008Meunier, A., Mas, A., Beaufort, D., Patrier, P., Dudoignon, P. (2008) Clay minerals in basalt-hawaiite rocks from Mururoa Atoll (French Polynesia). II. Petrography and geochemistry. Clays and Clay Minerals 56, 730–750.
; Meunier, 2010Meunier, A. (2010) Clays. Springer-Verlag, Berlin, Heidelberg, New York.
).Figure 1 SEM images of the investigated thin section of Nakhla in BSE mode. (a) BSE image of the augite cumulate texture of Nakhla. (b,c) BSE image of the Nakhla mesostasis (b) and corresponding EDXS-based mineralogical map (c). (d–f) BSE images of the tardi-magmatic Fe/Mg-rich clay minerals observed in the mesostasis of Nakhla in contact with Na/Ca-plagioclase, K-feldspar, quartz and Cl-apatite.
Figure 2 TEM images of the FIB sections extracted from the mesostasis of Nakhla in STEM mode. (a–e). Images of the magmatic Fe/Mg-rich clay minerals minerals observed in the mesostasis of Nakhla in contact with K-feldspar, quartz, Cl-apatite and in inclusions within K-feldspar.
The inclusions of Fe/Mg-rich clay minerals within K-feldspar grains (Fig. 2) and the absence of chlorite and/or Al-rich layers are inconsistent with aqueous alteration processes of K-feldspars (Meunier, 2010
Meunier, A. (2010) Clays. Springer-Verlag, Berlin, Heidelberg, New York.
; Beaufort et al., 2015Beaufort, D., Rigault, C., Billon, S., Billault, V., Inoue, A., Inoué, S., Patrier, P. (2015) Chlorite and chloritization processes through mixed-layer mineral series in low-temperature geological systems – a review. Clay Minerals 50, 497–523.
). None of the Cl-apatite, K-feldspar and quartz grains composing the mesostasis of Nakhla display any alteration texture such as retreating surfaces or pitch-like material resulting from dissolution. In contrast, all these phases exhibit sharp boundaries, even when in contact with the Fe/Mg-rich clay minerals. A halogen content as high as that of these Fe/Mg-rich clay minerals has never been reported for secondary clay minerals (Bailey, 1984Bailey, S.W. (1984) Micas. Reviews in Mineralogy 13, Mineralogical Society of America, Washington, USA.
). The high chlorine content of the Fe/Mg-rich clay minerals observed in Nakhla is more consistent with a precipitation from a Cl-rich, magma derived fluid (Bailey, 1984Bailey, S.W. (1984) Micas. Reviews in Mineralogy 13, Mineralogical Society of America, Washington, USA.
), as is the case for the other Cl-rich minerals previously reported in nakhlites, such as apatite, scapolite and amphibole (Filiberto and Treiman, 2009aFiliberto, J., Treiman, A.H. (2009a) Martian magmas contained abundant chlorine, but little water. Geology 37, 1087–1090.
; McCubbin et al., 2013McCubbin, F.M., Elardo, S.M., Shearer, C.K., Smirnov, A., Hauri, E.H., Draper, D.S. (2013) A petrogenetic model for the comagmatic origin of chassignites and nakhlites: Inferences from chlorine-rich minerals, petrology, and geochemistry. Meteoritics & Planetary Science 48, 819–853.
; Filiberto et al., 2014Filiberto, J., Treiman, A.H., Giesting, P.A., Goodrich, C.A., Gross, J. (2014) High-temperature chlorine-rich fluid in the martian crust: A precursor to habitability. Earth and Planetary Science Letters 401, 110–115.
; Giesting and Filiberto, 2016Giesting, P.A., Filiberto, J. (2016) The formation environment of potassic-chloro-hastingsite in the nakhlites MIL 03346 and pairs and NWA 5790: Insights from terrestrial chloro-amphibole. Meteoritics & Planetary Science 51, 2127–2153.
). In other words, the Fe/Mg-rich clay minerals observed in Nakhla were not produced by aqueous alteration, but rather have a tardi-magmatic origin. Tardi-magmatic precipitation of smectite and celadonite similar to that observed here in Nakhla has been previously reported in terrestrial rocks (Meunier et al., 2008Meunier, A., Mas, A., Beaufort, D., Patrier, P., Dudoignon, P. (2008) Clay minerals in basalt-hawaiite rocks from Mururoa Atoll (French Polynesia). II. Petrography and geochemistry. Clays and Clay Minerals 56, 730–750.
, 2012Meunier, A., Petit, S., Ehlmann, B.L., Dudoignon, P., Westall, F., Mas, A., El Albani, A., Ferrage, E. (2012) Magmatic precipitation as a possible origin of Noachian clays on Mars. Nature Geoscience 5, 739.
; Meunier, 2010Meunier, A. (2010) Clays. Springer-Verlag, Berlin, Heidelberg, New York.
; Berger et al., 2014Berger, G., Meunier, A., Beaufort, D. (2014) Clay mineral formation on Mars: Chemical constraints and possible contribution of basalt out-gassing. Planetary Geology Field Symposium, Kitakyushu, Japan, 2011: Planetary Geology and Terrestrial Analogs 95, 25–32.
, 2018Berger, G., Beaufort, D., Antoine, R. (2018) Clay minerals related to the late magmatic activity of the Piton des Neiges (Réunion Island): consequence for the primitive crusts. Clay Minerals 53, 675–690.
).Petrographic investigations reveal that the tardi-magmatic Fe/Mg-rich clay minerals observed in Nakhla precipitated at the end of the cooling sequence from a residual water-rich, magma derived, Cl-rich fluid (Fig. 3). According to previous studies, the parental melt of Nakhla results from a mixture of different magmas with a Cl-rich fluid of some kind (McCubbin et al., 2013
McCubbin, F.M., Elardo, S.M., Shearer, C.K., Smirnov, A., Hauri, E.H., Draper, D.S. (2013) A petrogenetic model for the comagmatic origin of chassignites and nakhlites: Inferences from chlorine-rich minerals, petrology, and geochemistry. Meteoritics & Planetary Science 48, 819–853.
; Giesting and Filiberto, 2016Giesting, P.A., Filiberto, J. (2016) The formation environment of potassic-chloro-hastingsite in the nakhlites MIL 03346 and pairs and NWA 5790: Insights from terrestrial chloro-amphibole. Meteoritics & Planetary Science 51, 2127–2153.
). The crystallisation of Mg-rich augite cores followed by the overgrowth of Fe-rich rims increased the relative concentrations of Na, Ca and Al in the trapped, residual, evolved melt. Laths of Na/Ca-plagioclase then nucleated together with euhedral titanomagnetite at the surface of the augite grains, before the crystallisation of K-feldspar, quartz and Cl-apatite in between the laths of Na/Ca-plagioclase (Fig. 3). Finally, the observed Fe/Mg-rich clay minerals directly precipitated from the leaving residual water-rich, magma derived, Cl-rich fluid (Fig. 3). The differences in porosity between different pockets of clay minerals might result from the cooling history of the lava flow and/or the variable gas content of the residual water-rich, magma derived, Cl-rich fluids from which the clay minerals precipitated.Figure 3 Sketch summarising the crystallisation sequence of the mesostasis of Nakhla. (a) Crystallisation of augite and entrapment of a fraction of the residual melt. (b) Crystallisation of Fe-rich rims of augite. (c) Crystallisation of Na/Ca-plagioclase and Fe/Ti-oxides. (d) Crystallisation of K-feldspars, Cl-apatite and quartz. (e) Precipitation of Cl-rich Fe/Mg-clay minerals.
The precipitation of Fe/Mg-rich clay minerals after that of quartz might be due the low H2O content of the parental melt of nakhlites (Weis et al., 2017
Weis, F.A., Bellucci, J.J., Skogby, H., Stalder, R., Nemchin, A.A., Whitehouse, M.J. (2017) Water content in the Martian mantle: A Nakhla perspective. Geochimica et Cosmochimica Acta 212, 84–98.
; Filiberto et al., 2019Filiberto, J., McCubbin, F.M., Taylor, G.J. (2019) Chapter 2 – Volatiles in Martian Magmas and the Interior: Inputs of Volatiles Into the Crust and Atmosphere. In: Filiberto, J., Schwenzer, S.P. (Eds.) Volatiles in the Martian Crust, 13–33. Elsevier, Amsterdam, Netherlands.
). In fact, early experimental studies demonstrated that H2O-poor melts produce feldspar and quartz before phyllosilicates (Naney, 1983Naney, M.T. (1983) Phase equilibria of rock-forming ferromagnesian silicates in granitic systems. American Journal of Science 283, 993–1033.
). Of note, despite the low H2O content of the parental melt of nakhlites (e.g., <100 ppm; Weis et al., 2017Weis, F.A., Bellucci, J.J., Skogby, H., Stalder, R., Nemchin, A.A., Whitehouse, M.J. (2017) Water content in the Martian mantle: A Nakhla perspective. Geochimica et Cosmochimica Acta 212, 84–98.
and Filiberto et al., 2019Filiberto, J., McCubbin, F.M., Taylor, G.J. (2019) Chapter 2 – Volatiles in Martian Magmas and the Interior: Inputs of Volatiles Into the Crust and Atmosphere. In: Filiberto, J., Schwenzer, S.P. (Eds.) Volatiles in the Martian Crust, 13–33. Elsevier, Amsterdam, Netherlands.
), the final mineral assemblage observed here (i.e. Cl apatite, K feldspar, quartz and Fe/Mg-rich clay minerals) is typical of evolved/granitic rocks, even though it has long been argued that a significant H2O content is required to produce such rocks (Campbell and Taylor, 1983Campbell, I.H., Taylor, S.R. (1983) No water, no granites – No oceans, no continents. Geophysical Research Letters 10, 1061–1064.
). This apparent paradox can be explained by the high Cl content of the parental melt of nakhlites. In fact, the presence of Cl in a magma affects its liquidus temperature and increases pyroxene stability to lower pressures as does H2O, permitting the residual melt to evolve to lower temperatures before solidification (Filiberto and Treiman, 2009aFiliberto, J., Treiman, A.H. (2009a) Martian magmas contained abundant chlorine, but little water. Geology 37, 1087–1090.
,bFiliberto, J., Treiman, A.H. (2009b) The effect of chlorine on the liquidus of basalt: First results and implications for basalt genesis on Mars and Earth. Chemical Geology 263, 60–68.
), eventually leading to alkali-rich/felsic compositions like those obtained from H2O-rich melts (Nekvasil et al., 2004Nekvasil, H., Dondolini, A., Horn, J., Filiberto, J., Long, H., Lindsley, D.H. (2004) The Origin and Evolution of Silica-saturated Alkalic Suites: an Experimental Study. Journal of Petrology 45, 693–721.
; Whitaker et al., 2008Whitaker, M.L., Nekvasil, H., Lindsley, D.H., McCurry, M. (2008) Can crystallization of olivine tholeiite give rise to potassic rhyolites?—an experimental investigation. Bulletin of Volcanology 70, 417–434.
).Altogether, the results of the present study portend that some the Fe/Mg-rich clay minerals detected on Mars so far may not be the products of the aqueous alteration of pre-existing silicates by (sub)surface water but rather tardi-magmatic clays minerals, as anticipated earlier (Meunier et al., 2012
Meunier, A., Petit, S., Ehlmann, B.L., Dudoignon, P., Westall, F., Mas, A., El Albani, A., Ferrage, E. (2012) Magmatic precipitation as a possible origin of Noachian clays on Mars. Nature Geoscience 5, 739.
; Berger et al., 2014Berger, G., Meunier, A., Beaufort, D. (2014) Clay mineral formation on Mars: Chemical constraints and possible contribution of basalt out-gassing. Planetary Geology Field Symposium, Kitakyushu, Japan, 2011: Planetary Geology and Terrestrial Analogs 95, 25–32.
, 2018Berger, G., Beaufort, D., Antoine, R. (2018) Clay minerals related to the late magmatic activity of the Piton des Neiges (Réunion Island): consequence for the primitive crusts. Clay Minerals 53, 675–690.
). Similarly, some of the evolved units detected from orbit and containing Fe/Mg-rich clay minerals (Christensen et al., 2005Christensen, P.R., McSween, H.Y., Bandfield, J.L., Ruff, S.W., Rogers, A.D., Hamilton, V.E., Gorelick, N., Wyatt, M.B., Jakosky, B.M., Kieffer, H.H., Malin, M.C., Moersch, J.E. (2005) Evidence for magmatic evolution and diversity on Mars from infrared observations. Nature 436, 504–509.
; Bandfield, 2006Bandfield, J.L. (2006) Extended surface exposures of granitoid compositions in Syrtis Major, Mars. Geophysical Research Letters 33, L06203.
; Carter and Poulet, 2013Carter, J., Poulet, F. (2013) Ancient plutonic processes on Mars inferred from the detection of possible anorthositic terrains. Nature Geoscience 6, 1008.
; Wray et al., 2013Wray, J.J., Hansen, S.T., Dufek, J., Swayze, G.A., Murchie, S.L., Seelos, F.P., Skok, J.R., Irwin III, R.P., Ghiorso, M.S. (2013) Prolonged magmatic activity on Mars inferred from the detection of felsic rocks. Nature Geoscience 6, 1013.
) may not be mafic rocks having undergone aqueous alteration processes but rather evolved/granitic materials containing primary Fe/Mg clay minerals that formed via igneous differentiation. Given that Noachian magmas were richer in H2O (Médard and Grove, 2006Médard, E., Grove, T.L. (2006) Early hydrous melting and degassing of the Martian interior. Journal of Geophysical Research: Planets 111, E11003.
; Filiberto et al., 2019Filiberto, J., McCubbin, F.M., Taylor, G.J. (2019) Chapter 2 – Volatiles in Martian Magmas and the Interior: Inputs of Volatiles Into the Crust and Atmosphere. In: Filiberto, J., Schwenzer, S.P. (Eds.) Volatiles in the Martian Crust, 13–33. Elsevier, Amsterdam, Netherlands.
), both igneous differentiation and tardi-magmatic production of clay minerals may have been quite significant during the Noachian. Determining the exact contribution of these processes during the Noachian could potentially resolve the origin of the Martian dichotomy (Watters et al., 2007Watters, T.R., McGovern, P.J., Irwin III, R.P. (2007) Hemispheres Apart: The Crustal Dichotomy on Mars. Annual Review of Earth and Planetary Sciences 35, 621–652.
) and explain both the missing salt paradox (Milliken et al., 2009Milliken, R.E., Fischer, W.W., Hurowitz, J.A. (2009) Missing salts on early Mars. Geophysical Research Letters 36, L11202.
) and the amorphous conundrum (Tosca and Knoll, 2009Tosca, N.J., Knoll, A.H. (2009) Juvenile chemical sediments and the long term persistence of water at the surface of Mars. Earth and Planetary Science Letters 286, 379–386.
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Acknowledgements
We gratefully acknowledge financial support from the ANR (project RAHIIA_SSOM – Local PI: LR). We thank Elisabeth Malassis for administrative support, Imène Esteve (IMPMC) for support with the SEM, David Troadec (IEMN) for the preparation of FIB sections. The SEM facility at IMPMC is supported by Region Ile de France grant SESAME Number I-07-593/R, INSU-CNRS, INP-CNRS and UPMC-Paris 6, and by the Agence Nationale de la Recherche (ANR) grant number ANR-07-BLAN-0124-01. The TEM facility at the CCM (Lille University) is supported by the Chevreul Institute, the European FEDER and Région Nord-Pas-de-Calais. The authors wish to acknowledge the Editor Pr. Maud Boyet, as well as two anonymous reviewers, for their constructive comments that greatly improved the quality of this work.
Editor: Maud Boyet
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Author Contributions
JCV and SB designed the present study, with critical inputs from CLG and VS. JCV and SB performed the SEM analyses. JCV, SB and CLG performed the TEM analyses. JCV and CLG processed the EXDS data. All authors contributed to the interpretation of the data and discussed their implications. JVC and SB wrote the manuscript, with critical inputs from all authors.
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References
Bailey, S.W. (1984) Micas. Reviews in Mineralogy 13, Mineralogical Society of America, Washington, USA.
Show in contextA halogen content as high as that of these Fe/Mg-rich clay minerals has never been reported for secondary clay minerals (Bailey, 1984).
View in article
The high chlorine content of the Fe/Mg-rich clay minerals observed in Nakhla is more consistent with a precipitation from a Cl-rich, magma derived fluid (Bailey, 1984), as is the case for the other Cl-rich minerals previously reported in nakhlites, such as apatite, scapolite and amphibole (Filiberto and Treiman, 2009a; McCubbin et al., 2013; Filiberto et al., 2014; Giesting and Filiberto, 2016).
View in article
Bandfield, J.L. (2006) Extended surface exposures of granitoid compositions in Syrtis Major, Mars. Geophysical Research Letters 33, L06203.
Show in contextOnly rare exposures of evolved rocks containing hydrated silica and/or quartz have been reported from orbit (Christensen et al., 2005; Bandfield, 2006; Carter and Poulet, 2013; Wray et al., 2013).
View in article
Similarly, some of the evolved units detected from orbit and containing Fe/Mg-rich clay minerals (Christensen et al., 2005; Bandfield, 2006; Carter and Poulet, 2013; Wray et al., 2013) may not be mafic rocks having undergone aqueous alteration processes but rather evolved/granitic materials containing primary Fe/Mg clay minerals that formed via igneous differentiation.
View in article
Beaufort, D., Rigault, C., Billon, S., Billault, V., Inoue, A., Inoué, S., Patrier, P. (2015) Chlorite and chloritization processes through mixed-layer mineral series in low-temperature geological systems – a review. Clay Minerals 50, 497–523.
Show in contextThe inclusions of Fe/Mg-rich clay minerals within K-feldspar grains (Fig. 2) and the absence of chlorite and/or Al-rich layers are inconsistent with aqueous alteration processes of K-feldspars (Meunier, 2010; Beaufort et al., 2015).
View in article
Berger, G., Meunier, A., Beaufort, D. (2014) Clay mineral formation on Mars: Chemical constraints and possible contribution of basalt out-gassing. Planetary Geology Field Symposium, Kitakyushu, Japan, 2011: Planetary Geology and Terrestrial Analogs 95, 25–32.
Show in contextTardi-magmatic precipitation of smectite and celadonite similar to that observed here in Nakhla has been previously reported in terrestrial rocks (Meunier et al., 2008, 2012; Meunier, 2010; Berger et al., 2014, 2018).
View in article
Altogether, the results of the present study portend that some the Fe/Mg-rich clay minerals detected on Mars so far may not be the products of the aqueous alteration of pre-existing silicates by (sub)surface water but rather tardi-magmatic clays minerals, as anticipated earlier (Meunier et al., 2012; Berger et al., 2014, 2018).
View in article
Berger, G., Beaufort, D., Antoine, R. (2018) Clay minerals related to the late magmatic activity of the Piton des Neiges (Réunion Island): consequence for the primitive crusts. Clay Minerals 53, 675–690.
Show in contextTardi-magmatic precipitation of smectite and celadonite similar to that observed here in Nakhla has been previously reported in terrestrial rocks (Meunier et al., 2008, 2012; Meunier, 2010; Berger et al., 2014, 2018).
View in article
Altogether, the results of the present study portend that some the Fe/Mg-rich clay minerals detected on Mars so far may not be the products of the aqueous alteration of pre-existing silicates by (sub)surface water but rather tardi-magmatic clays minerals, as anticipated earlier (Meunier et al., 2012; Berger et al., 2014, 2018).
View in article
Bischoff, A., Horstmann, M., Barrat, J.-A., Chaussidon, M., Pack, A., Herwartz, D., Ward, D., Vollmer, C., Decker, S. (2014) Trachyandesitic volcanism in the early Solar System. Proceedings of the National Academy of Sciences 111, 12689.
Show in contextRecent discoveries have provided direct evidence that chemically evolved rocks formed over short timescales on planetesimals early in the Solar System (Day et al., 2009; Bischoff et al., 2014; Frossard et al., 2019).
View in article
Bouley, S., Keane, J.T., Baratoux, D., Langlais, B., Matsuyama, I., Costard, F., Hewins, R., Payré, V., Sautter, V., Séjourné, A. et al. (2020) A thick crustal block revealed by reconstructions of early Mars highlands. Nature Geoscience 13, 105–109.
Show in contextHowever, it is unclear if and how much such evolved rocks contributed to the ancient crust of Mars (Sautter et al., 2015, 2016; Udry et al., 2018; Bouley et al., 2020).
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Bridges, J.C., Catling, D.C., Saxton, J.M., Swindle, T.D., Lyon, I.C., Grady, M.M. (2001) Alteration Assemblages in Martian Meteorites: Implications for Near-Surface Processes. Space Science Reviews 96, 365–392.
Show in contextBecause of the presence of Fe/Mg-rich clay minerals interpreted as secondary aqueous alteration products (Gooding et al., 1991; Bridges et al., 2001; Carter and Poulet, 2013; Wray et al., 2013; Hicks et al., 2014), the rare evolved rocks detected from orbit have been interpreted as resulting from the hydrothermal alteration or diagenesis of mafic crustal materials (Smith and Bandfield, 2012; Ehlmann and Edwards, 2014).
View in article
Campbell, I.H., Taylor, S.R. (1983) No water, no granites – No oceans, no continents. Geophysical Research Letters 10, 1061–1064.
Show in contextOf note, despite the low H2O content of the parental melt of nakhlites (e.g., <100 ppm; Weis et al., 2017 and Filiberto et al., 2019), the final mineral assemblage observed here (i.e. Cl apatite, K feldspar, quartz and Fe/Mg-rich clay minerals) is typical of evolved/granitic rocks, even though it has long been argued that a significant H2O content is required to produce such rocks (Campbell and Taylor, 1983).
View in article
Carter, J., Poulet, F. (2013) Ancient plutonic processes on Mars inferred from the detection of possible anorthositic terrains. Nature Geoscience 6, 1008.
Show in contextOnly rare exposures of evolved rocks containing hydrated silica and/or quartz have been reported from orbit (Christensen et al., 2005; Bandfield, 2006; Carter and Poulet, 2013; Wray et al., 2013).
View in article
Because of the presence of Fe/Mg-rich clay minerals interpreted as secondary aqueous alteration products (Gooding et al., 1991; Bridges et al., 2001; Carter and Poulet, 2013; Wray et al., 2013; Hicks et al., 2014), the rare evolved rocks detected from orbit have been interpreted as resulting from the hydrothermal alteration or diagenesis of mafic crustal materials (Smith and Bandfield, 2012; Ehlmann and Edwards, 2014).
View in article
Similarly, some of the evolved units detected from orbit and containing Fe/Mg-rich clay minerals (Christensen et al., 2005; Bandfield, 2006; Carter and Poulet, 2013; Wray et al., 2013) may not be mafic rocks having undergone aqueous alteration processes but rather evolved/granitic materials containing primary Fe/Mg clay minerals that formed via igneous differentiation.
View in article
Christensen, P.R., McSween, H.Y., Bandfield, J.L., Ruff, S.W., Rogers, A.D., Hamilton, V.E., Gorelick, N., Wyatt, M.B., Jakosky, B.M., Kieffer, H.H., Malin, M.C., Moersch, J.E. (2005) Evidence for magmatic evolution and diversity on Mars from infrared observations. Nature 436, 504–509.
Show in contextOnly rare exposures of evolved rocks containing hydrated silica and/or quartz have been reported from orbit (Christensen et al., 2005; Bandfield, 2006; Carter and Poulet, 2013; Wray et al., 2013).
View in article
Similarly, some of the evolved units detected from orbit and containing Fe/Mg-rich clay minerals (Christensen et al., 2005; Bandfield, 2006; Carter and Poulet, 2013; Wray et al., 2013) may not be mafic rocks having undergone aqueous alteration processes but rather evolved/granitic materials containing primary Fe/Mg clay minerals that formed via igneous differentiation.
View in article
Day, J.M.D., Ash, R.D., Liu, Y., Bellucci, J.J., III, D.R., McDonough, W.F., Walker, R.J., Taylor, L.A. (2009) Early formation of evolved asteroidal crust. Nature 457, 179–182.
Show in contextRecent discoveries have provided direct evidence that chemically evolved rocks formed over short timescales on planetesimals early in the Solar System (Day et al., 2009; Bischoff et al., 2014; Frossard et al., 2019).
View in article
Ehlmann, B.L., Edwards, C.S. (2014) Mineralogy of the Martian Surface. Annual Review of Earth and Planetary Sciences 42, 291–315.
Show in contextIn addition to the small depth analysed, that makes dust and coatings dominate the signal, difficulties pertain to the spectral featureless of the main constituents of evolved rocks (e.g., feldspar and quartz), leading to some much discussed ambiguities (Smith and Bandfield, 2012; Ehlmann and Edwards, 2014; Rogers and Nekvasil, 2015).
View in article
Because of the presence of Fe/Mg-rich clay minerals interpreted as secondary aqueous alteration products (Gooding et al., 1991; Bridges et al., 2001; Carter and Poulet, 2013; Wray et al., 2013; Hicks et al., 2014), the rare evolved rocks detected from orbit have been interpreted as resulting from the hydrothermal alteration or diagenesis of mafic crustal materials (Smith and Bandfield, 2012; Ehlmann and Edwards, 2014).
View in article
Filiberto, J., McCubbin, F.M., Taylor, G.J. (2019) Chapter 2 – Volatiles in Martian Magmas and the Interior: Inputs of Volatiles Into the Crust and Atmosphere. In: Filiberto, J., Schwenzer, S.P. (Eds.) Volatiles in the Martian Crust, 13–33. Elsevier, Amsterdam, Netherlands.
Show in contextThe precipitation of Fe/Mg-rich clay minerals after that of quartz might be due the low H2O content of the parental melt of nakhlites (Weis et al., 2017; Filiberto et al., 2019).
View in article
Of note, despite the low H2O content of the parental melt of nakhlites (e.g., <100 ppm; Weis et al., 2017 and Filiberto et al., 2019), the final mineral assemblage observed here (i.e. Cl apatite, K feldspar, quartz and Fe/Mg-rich clay minerals) is typical of evolved/granitic rocks, even though it has long been argued that a significant H2O content is required to produce such rocks (Campbell and Taylor, 1983).
View in article
Given that Noachian magmas were richer in H2O (Médard and Grove, 2006; Filiberto et al., 2019), both igneous differentiation and tardi-magmatic production of clay minerals may have been quite significant during the Noachian.
View in article
Filiberto, J., Treiman, A.H. (2009a) Martian magmas contained abundant chlorine, but little water. Geology 37, 1087–1090.
Show in contextThe high chlorine content of the Fe/Mg-rich clay minerals observed in Nakhla is more consistent with a precipitation from a Cl-rich, magma derived fluid (Bailey, 1984), as is the case for the other Cl-rich minerals previously reported in nakhlites, such as apatite, scapolite and amphibole (Filiberto and Treiman, 2009a; McCubbin et al., 2013; Filiberto et al., 2014; Giesting and Filiberto, 2016).
View in article
In fact, the presence of Cl in a magma affects its liquidus temperature and increases pyroxene stability to lower pressures as does H2O, permitting the residual melt to evolve to lower temperatures before solidification (Filiberto and Treiman, 2009a,b), eventually leading to alkali-rich/felsic compositions like those obtained from H2O-rich melts (Nekvasil et al., 2004; Whitaker et al., 2008).
View in article
Filiberto, J., Treiman, A.H. (2009b) The effect of chlorine on the liquidus of basalt: First results and implications for basalt genesis on Mars and Earth. Chemical Geology 263, 60–68.
Show in contextIn fact, the presence of Cl in a magma affects its liquidus temperature and increases pyroxene stability to lower pressures as does H2O, permitting the residual melt to evolve to lower temperatures before solidification (Filiberto and Treiman, 2009a,b), eventually leading to alkali-rich/felsic compositions like those obtained from H2O-rich melts (Nekvasil et al., 2004; Whitaker et al., 2008).
View in article
Filiberto, J., Treiman, A.H., Giesting, P.A., Goodrich, C.A., Gross, J. (2014) High-temperature chlorine-rich fluid in the martian crust: A precursor to habitability. Earth and Planetary Science Letters 401, 110–115.
Show in contextThe high chlorine content of the Fe/Mg-rich clay minerals observed in Nakhla is more consistent with a precipitation from a Cl-rich, magma derived fluid (Bailey, 1984), as is the case for the other Cl-rich minerals previously reported in nakhlites, such as apatite, scapolite and amphibole (Filiberto and Treiman, 2009a; McCubbin et al., 2013; Filiberto et al., 2014; Giesting and Filiberto, 2016).
View in article
Frossard, P., Boyet, M., Bouvier, A., Hammouda, T., Monteux, J. (2019) Evidence for anorthositic crust formed on an inner solar system planetesimal. Geochemical Perspectives Letters 11, 28–32.
Show in contextRecent discoveries have provided direct evidence that chemically evolved rocks formed over short timescales on planetesimals early in the Solar System (Day et al., 2009; Bischoff et al., 2014; Frossard et al., 2019).
View in article
Giesting, P.A., Filiberto, J. (2016) The formation environment of potassic-chloro-hastingsite in the nakhlites MIL 03346 and pairs and NWA 5790: Insights from terrestrial chloro-amphibole. Meteoritics & Planetary Science 51, 2127–2153.
Show in contextConsistently monzonitic clasts have been found in Black Beauty (Humayun et al., 2013; Hewins et al., 2017), while K-feldspar, SiO2 polymorphs (cristobalite, trydimite and quartz) and even rhyolitic glass have been observed (in addition to apatite and zircon) within nakhlites (Treiman, 2005; Nekvasil et al., 2007; McCubbin et al., 2013; Giesting and Filiberto, 2016).
View in article
The high chlorine content of the Fe/Mg-rich clay minerals observed in Nakhla is more consistent with a precipitation from a Cl-rich, magma derived fluid (Bailey, 1984), as is the case for the other Cl-rich minerals previously reported in nakhlites, such as apatite, scapolite and amphibole (Filiberto and Treiman, 2009a; McCubbin et al., 2013; Filiberto et al., 2014; Giesting and Filiberto, 2016).
View in article
Gooding, J.L., Wentworth, S.J., Zolensky, M.E. (1991) Aqueous alteration of the Nakhla meteorite. Meteoritics 26, 135–143.
Show in contextBecause of the presence of Fe/Mg-rich clay minerals interpreted as secondary aqueous alteration products (Gooding et al., 1991; Bridges et al., 2001; Carter and Poulet, 2013; Wray et al., 2013; Hicks et al., 2014), the rare evolved rocks detected from orbit have been interpreted as resulting from the hydrothermal alteration or diagenesis of mafic crustal materials (Smith and Bandfield, 2012; Ehlmann and Edwards, 2014).
View in article
In contrast to iddingsite veins crosscutting olivine in nakhlites (Gooding et al., 1991), these Fe/Mg-rich clay minerals display a high porosity and can be found as masses in contact with or within Na/Ca-plagioclase, Cl-apatite, K-feldspar or quartz (Figs. 1, 2).
View in article
Hewins, R.H., Zanda, B., Humayun, M., Nemchin, A., Lorand, J.-P., Pont, S., Deldicque, D., Bellucci, J.J., Beck, P., Leroux, H., Marinova, M., Remusat, L., Göpel, C., Lewin, E., Grange, M., Kennedy, A., Whitehouse, M.J. (2017) Regolith breccia Northwest Africa 7533: Mineralogy and petrology with implications for early Mars. Meteoritics & Planetary Science 52, 89–124.
Show in contextConsistently monzonitic clasts have been found in Black Beauty (Humayun et al., 2013; Hewins et al., 2017), while K-feldspar, SiO2 polymorphs (cristobalite, trydimite and quartz) and even rhyolitic glass have been observed (in addition to apatite and zircon) within nakhlites (Treiman, 2005; Nekvasil et al., 2007; McCubbin et al., 2013; Giesting and Filiberto, 2016).
View in article
Hicks, L.J., Bridges, J.C., Gurman, S.J. (2014) Ferric saponite and serpentine in the nakhlite martian meteorites. Geochimica et Cosmochimica Acta 136, 194–210.
Show in contextBecause of the presence of Fe/Mg-rich clay minerals interpreted as secondary aqueous alteration products (Gooding et al., 1991; Bridges et al., 2001; Carter and Poulet, 2013; Wray et al., 2013; Hicks et al., 2014), the rare evolved rocks detected from orbit have been interpreted as resulting from the hydrothermal alteration or diagenesis of mafic crustal materials (Smith and Bandfield, 2012; Ehlmann and Edwards, 2014).
View in article
Humayun, M., Nemchin, A., Zanda, B., Hewins, R.H., Grange, M., Kennedy, A., Lorand, J.-P., Göpel, C., Fieni, C., Pont, S., Deldicque, D. (2013) Origin and age of the earliest Martian crust from meteorite NWA 7533. Nature 503, 513–516.
Show in contextConsistently monzonitic clasts have been found in Black Beauty (Humayun et al., 2013; Hewins et al., 2017), while K-feldspar, SiO2 polymorphs (cristobalite, trydimite and quartz) and even rhyolitic glass have been observed (in addition to apatite and zircon) within nakhlites (Treiman, 2005; Nekvasil et al., 2007; McCubbin et al., 2013; Giesting and Filiberto, 2016).
View in article
McCubbin, F.M., Elardo, S.M., Shearer, C.K., Smirnov, A., Hauri, E.H., Draper, D.S. (2013) A petrogenetic model for the comagmatic origin of chassignites and nakhlites: Inferences from chlorine-rich minerals, petrology, and geochemistry. Meteoritics & Planetary Science 48, 819–853.
Show in contextAccording to previous studies, the parental melt of Nakhla results from a mixture of different magmas with a Cl-rich fluid of some kind (McCubbin et al., 2013; Giesting and Filiberto, 2016).
View in article
Consistently monzonitic clasts have been found in Black Beauty (Humayun et al., 2013; Hewins et al., 2017), while K-feldspar, SiO2 polymorphs (cristobalite, trydimite and quartz) and even rhyolitic glass have been observed (in addition to apatite and zircon) within nakhlites (Treiman, 2005; Nekvasil et al., 2007; McCubbin et al., 2013; Giesting and Filiberto, 2016).
View in article
The consensus is that nakhlites and chassignites sampled different levels of what may have been a single, large igneous complex (McCubbin et al., 2013), with nakhlites having crystallised from the residual melt having first produced chassignites (Udry and Day, 2018).
View in article
The high chlorine content of the Fe/Mg-rich clay minerals observed in Nakhla is more consistent with a precipitation from a Cl-rich, magma derived fluid (Bailey, 1984), as is the case for the other Cl-rich minerals previously reported in nakhlites, such as apatite, scapolite and amphibole (Filiberto and Treiman, 2009a; McCubbin et al., 2013; Filiberto et al., 2014; Giesting and Filiberto, 2016).
View in article
McSween, H.Y., Murchie, S.L., Crisp, J.A., Bridges, N.T., Anderson, R.C., Bell III, J.F., Britt, D.T., Brückner, J., Dreibus, G., Economou, T., Ghosh, A., Golombek, M.P., Greenwood, J.P., Johnson, J.R., Moore, H.J., Morris, R.V., Parker, T.J., Rieder, R., Singer, R., Wänke, H. (1999) Chemical, multispectral, and textural constraints on the composition and origin of rocks at the Mars Pathfinder landing site. Journal of Geophysical Research: Planets 104, 8679–8715.
Show in contextYet, robotic missions evidenced that igneous differentiation induced by fractional crystallisation occurred on Mars (McSween et al., 1999, 2006; Stolper et al., 2013; Sautter et al., 2015, 2016; Udry et al., 2018).
View in article
McSween, H.Y., Ruff, S.W., Morris, R.V., Bell III, J.F., Herkenhoff, K., Gellert, R., Stockstill, K.R., Tornabene, L.L., Squyres, S.W., Crisp, J.A., Christensen, P.R., McCoy, T.J., Mittlefehldt, D.W., Schmidt, M. (2006) Alkaline volcanic rocks from the Columbia Hills, Gusev crater, Mars. Journal of Geophysical Research: Planets 111.
Show in contextYet, robotic missions evidenced that igneous differentiation induced by fractional crystallisation occurred on Mars (McSween et al., 1999, 2006; Stolper et al., 2013; Sautter et al., 2015, 2016; Udry et al., 2018).
View in article
The Spirit rover encountered alkaline volcanic rocks, substantially enriched in Na/K-rich plagioclase relative to pyroxene and olivine (McSween et al., 2006), while Curiosity found both fine grained alkali basalts known as mugearites (Stolper et al., 2013) and coarse grained alkali feldspar-bearing lithologies (Sautter et al., 2015, 2016; Udry et al., 2018).
View in article
Médard, E., Grove, T.L. (2006) Early hydrous melting and degassing of the Martian interior. Journal of Geophysical Research: Planets 111, E11003.
Show in contextGiven that Noachian magmas were richer in H2O (Médard and Grove, 2006; Filiberto et al., 2019), both igneous differentiation and tardi-magmatic production of clay minerals may have been quite significant during the Noachian.
View in article
Meunier, A. (2010) Clays. Springer-Verlag, Berlin, Heidelberg, New York.
Show in contextTheir mean structural formula, (K0.22Na0.30Ca0.07(Mg0.93Fe0.58Mn0.05Ti0.02□0.42)(Fe0.93Al0.21Si2.86)(O10)[(OH,O)1.86,Cl0.14]) according to STEM-EDS analyses, falls within the domain of interstratified or mixtures of Cl-rich saponite and celadonite (Meunier et al., 2008; Meunier, 2010).
View in article
The inclusions of Fe/Mg-rich clay minerals within K-feldspar grains (Fig. 2) and the absence of chlorite and/or Al-rich layers are inconsistent with aqueous alteration processes of K-feldspars (Meunier, 2010; Beaufort et al., 2015).
View in article
Tardi-magmatic precipitation of smectite and celadonite similar to that observed here in Nakhla has been previously reported in terrestrial rocks (Meunier et al., 2008, 2012; Meunier, 2010; Berger et al., 2014, 2018).
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Meunier, A., Mas, A., Beaufort, D., Patrier, P., Dudoignon, P. (2008) Clay minerals in basalt-hawaiite rocks from Mururoa Atoll (French Polynesia). II. Petrography and geochemistry. Clays and Clay Minerals 56, 730–750.
Show in contextTheir mean structural formula, (K0.22Na0.30Ca0.07(Mg0.93Fe0.58Mn0.05Ti0.02□0.42)(Fe0.93Al0.21Si2.86)(O10)[(OH,O)1.86,Cl0.14]) according to STEM-EDS analyses, falls within the domain of interstratified or mixtures of Cl-rich saponite and celadonite (Meunier et al., 2008; Meunier, 2010).
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Tardi-magmatic precipitation of smectite and celadonite similar to that observed here in Nakhla has been previously reported in terrestrial rocks (Meunier et al., 2008, 2012; Meunier, 2010; Berger et al., 2014, 2018).
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Meunier, A., Petit, S., Ehlmann, B.L., Dudoignon, P., Westall, F., Mas, A., El Albani, A., Ferrage, E. (2012) Magmatic precipitation as a possible origin of Noachian clays on Mars. Nature Geoscience 5, 739.
Show in contextTardi-magmatic precipitation of smectite and celadonite similar to that observed here in Nakhla has been previously reported in terrestrial rocks (Meunier et al., 2008, 2012; Meunier, 2010; Berger et al., 2014, 2018).
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Altogether, the results of the present study portend that some the Fe/Mg-rich clay minerals detected on Mars so far may not be the products of the aqueous alteration of pre-existing silicates by (sub)surface water but rather tardi-magmatic clays minerals, as anticipated earlier (Meunier et al., 2012; Berger et al., 2014, 2018).
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Milliken, R.E., Fischer, W.W., Hurowitz, J.A. (2009) Missing salts on early Mars. Geophysical Research Letters 36, L11202.
Show in contextDetermining the exact contribution of these processes during the Noachian could potentially resolve the origin of the Martian dichotomy (Watters et al., 2007) and explain both the missing salt paradox (Milliken et al., 2009) and the amorphous conundrum (Tosca and Knoll, 2009).
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Naney, M.T. (1983) Phase equilibria of rock-forming ferromagnesian silicates in granitic systems. American Journal of Science 283, 993–1033.
Show in contextIn fact, early experimental studies demonstrated that H2O-poor melts produce feldspar and quartz before phyllosilicates (Naney, 1983).
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Nekvasil, H., Dondolini, A., Horn, J., Filiberto, J., Long, H., Lindsley, D.H. (2004) The Origin and Evolution of Silica-saturated Alkalic Suites: an Experimental Study. Journal of Petrology 45, 693–721.
Show in contextIn fact, the presence of Cl in a magma affects its liquidus temperature and increases pyroxene stability to lower pressures as does H2O, permitting the residual melt to evolve to lower temperatures before solidification (Filiberto and Treiman, 2009a,b), eventually leading to alkali-rich/felsic compositions like those obtained from H2O-rich melts (Nekvasil et al., 2004; Whitaker et al., 2008).
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Nekvasil, H., Filiberto, J., McCubbin, F.M., Lindsley, D.H. (2007) Alkalic parental magmas for chassignites? Meteoritics & Planetary Science 42, 979–992.
Show in contextConsistently monzonitic clasts have been found in Black Beauty (Humayun et al., 2013; Hewins et al., 2017), while K-feldspar, SiO2 polymorphs (cristobalite, trydimite and quartz) and even rhyolitic glass have been observed (in addition to apatite and zircon) within nakhlites (Treiman, 2005; Nekvasil et al., 2007; McCubbin et al., 2013; Giesting and Filiberto, 2016).
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Rogers, A.D., Nekvasil, H. (2015) Feldspathic rocks on Mars: Compositional constraints from infrared spectroscopy and possible formation mechanisms. Geophysical Research Letters 42, 2619–2626.
Show in contextIn addition to the small depth analysed, that makes dust and coatings dominate the signal, difficulties pertain to the spectral featureless of the main constituents of evolved rocks (e.g., feldspar and quartz), leading to some much discussed ambiguities (Smith and Bandfield, 2012; Ehlmann and Edwards, 2014; Rogers and Nekvasil, 2015).
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Sautter, V., Toplis, M.J., Wiens, R.C., Cousin, A., Fabre, C., Gasnault, O., Maurice, S., Forni, O., Lasue, J., Ollila, A., Bridges, J.C., Mangold, N., Le Mouélic, S., Fisk, M., Meslin, P.-Y., Beck, P., Pinet, P., Le Deit, L., Rapin, W., Stolper, E.M., Newsom, H., Dyar, D., Lanza, N., Vaniman, D., Clegg, S., Wray, J.J. (2015) In situ evidence for continental crust on early Mars. Nature Geoscience 8, 605.
Show in contextHowever, it is unclear if and how much such evolved rocks contributed to the ancient crust of Mars (Sautter et al., 2015, 2016; Udry et al., 2018; Bouley et al., 2020).
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Yet, robotic missions evidenced that igneous differentiation induced by fractional crystallisation occurred on Mars (McSween et al., 1999, 2006; Stolper et al., 2013; Sautter et al., 2015, 2016; Udry et al., 2018).
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The Spirit rover encountered alkaline volcanic rocks, substantially enriched in Na/K-rich plagioclase relative to pyroxene and olivine (McSween et al., 2006), while Curiosity found both fine grained alkali basalts known as mugearites (Stolper et al., 2013) and coarse grained alkali feldspar-bearing lithologies (Sautter et al., 2015, 2016; Udry et al., 2018).
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Sautter, V., Toplis, M.J., Beck, P., Mangold, N., Wiens, R., Pinet, P., Cousin, A., Maurice, S., LeDeit, L., Hewins, R., Gasnault, O., Quantin, C., Forni, O., Newsom, H., Meslin, P.-Y., Wray, J., Bridges, N., Payre, V., Rapin, W., Le Mouelic, S. (2016) Magmatic complexity on early Mars as seen through a combination of orbital, in-situ and meteorite data. Lithos 254, 36–52.
Show in contextHowever, it is unclear if and how much such evolved rocks contributed to the ancient crust of Mars (Sautter et al., 2015, 2016; Udry et al., 2018; Bouley et al., 2020).
View in article
Yet, robotic missions evidenced that igneous differentiation induced by fractional crystallisation occurred on Mars (McSween et al., 1999, 2006; Stolper et al., 2013; Sautter et al., 2015, 2016; Udry et al., 2018).
View in article
The Spirit rover encountered alkaline volcanic rocks, substantially enriched in Na/K-rich plagioclase relative to pyroxene and olivine (McSween et al., 2006), while Curiosity found both fine grained alkali basalts known as mugearites (Stolper et al., 2013) and coarse grained alkali feldspar-bearing lithologies (Sautter et al., 2015, 2016; Udry et al., 2018).
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Smith, M.R., Bandfield, J.L. (2012) Geology of quartz and hydrated silica-bearing deposits near Antoniadi Crater, Mars. Journal of Geophysical Research: Planets 117, E06007.
Show in contextIn addition to the small depth analysed, that makes dust and coatings dominate the signal, difficulties pertain to the spectral featureless of the main constituents of evolved rocks (e.g., feldspar and quartz), leading to some much discussed ambiguities (Smith and Bandfield, 2012; Ehlmann and Edwards, 2014; Rogers and Nekvasil, 2015).
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Because of the presence of Fe/Mg-rich clay minerals interpreted as secondary aqueous alteration products (Gooding et al., 1991; Bridges et al., 2001; Carter and Poulet, 2013; Wray et al., 2013; Hicks et al., 2014), the rare evolved rocks detected from orbit have been interpreted as resulting from the hydrothermal alteration or diagenesis of mafic crustal materials (Smith and Bandfield, 2012; Ehlmann and Edwards, 2014).
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Stolper, E.M., Baker, M.B., Newcombe, M.E., Schmidt, M.E., Treiman, A.H., Cousin, A., Dyar, M.D., Fisk, M.R., Gellert, R., King, P.L., Leshin, L., Maurice, S., McLennan, S.M., Minitti, M.E., Perrett, G., Rowland, S., Sautter, V., Wiens, R.C. (2013) The Petrochemistry of Jake_M: A Martian Mugearite. Science 341, 1239463.
Show in contextYet, robotic missions evidenced that igneous differentiation induced by fractional crystallisation occurred on Mars (McSween et al., 1999, 2006; Stolper et al., 2013; Sautter et al., 2015, 2016; Udry et al., 2018).
View in article
The Spirit rover encountered alkaline volcanic rocks, substantially enriched in Na/K-rich plagioclase relative to pyroxene and olivine (McSween et al., 2006), while Curiosity found both fine grained alkali basalts known as mugearites (Stolper et al., 2013) and coarse grained alkali feldspar-bearing lithologies (Sautter et al., 2015, 2016; Udry et al., 2018).
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Tosca, N.J., Knoll, A.H. (2009) Juvenile chemical sediments and the long term persistence of water at the surface of Mars. Earth and Planetary Science Letters 286, 379–386.
Show in contextDetermining the exact contribution of these processes during the Noachian could potentially resolve the origin of the Martian dichotomy (Watters et al., 2007) and explain both the missing salt paradox (Milliken et al., 2009) and the amorphous conundrum (Tosca and Knoll, 2009).
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Treiman, A.H. (2005) The nakhlite meteorites: Augite-rich igneous rocks from Mars. Geochemistry 65, 203–270.
Show in contextNakhlites are augite cumulates that differ from each other in the proportion and crystallinity of the mesostasis (Treiman, 2005).
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Consistently monzonitic clasts have been found in Black Beauty (Humayun et al., 2013; Hewins et al., 2017), while K-feldspar, SiO2 polymorphs (cristobalite, trydimite and quartz) and even rhyolitic glass have been observed (in addition to apatite and zircon) within nakhlites (Treiman, 2005; Nekvasil et al., 2007; McCubbin et al., 2013; Giesting and Filiberto, 2016).
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Udry, A., Day, J.M.D. (2018) 1.34 billion-year-old magmatism on Mars evaluated from the co-genetic nakhlite and chassignite meteorites. Geochimica et Cosmochimica Acta 238, 292–315.
Show in contextThey were emplaced ∼1.3 Gyr ago as multiple flows, dikes or sills close to the surface (Udry and Day, 2018).
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The consensus is that nakhlites and chassignites sampled different levels of what may have been a single, large igneous complex (McCubbin et al., 2013), with nakhlites having crystallised from the residual melt having first produced chassignites (Udry and Day, 2018).
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Udry, A., Gazel, E., McSween Jr., H.Y. (2018) Formation of Evolved Rocks at Gale Crater by Crystal Fractionation and Implications for Mars Crustal Composition. Journal of Geophysical Research: Planets 123, 1525–1540.
Show in contextHowever, it is unclear if and how much such evolved rocks contributed to the ancient crust of Mars (Sautter et al., 2015, 2016; Udry et al., 2018; Bouley et al., 2020).
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Yet, robotic missions evidenced that igneous differentiation induced by fractional crystallisation occurred on Mars (McSween et al., 1999, 2006; Stolper et al., 2013; Sautter et al., 2015, 2016; Udry et al., 2018).
View in article
Watters, T.R., McGovern, P.J., Irwin III, R.P. (2007) Hemispheres Apart: The Crustal Dichotomy on Mars. Annual Review of Earth and Planetary Sciences 35, 621–652.
Show in contextDetermining the exact contribution of these processes during the Noachian could potentially resolve the origin of the Martian dichotomy (Watters et al., 2007) and explain both the missing salt paradox (Milliken et al., 2009) and the amorphous conundrum (Tosca and Knoll, 2009).
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Weis, F.A., Bellucci, J.J., Skogby, H., Stalder, R., Nemchin, A.A., Whitehouse, M.J. (2017) Water content in the Martian mantle: A Nakhla perspective. Geochimica et Cosmochimica Acta 212, 84–98.
Show in contextThe precipitation of Fe/Mg-rich clay minerals after that of quartz might be due the low H2O content of the parental melt of nakhlites (Weis et al., 2017; Filiberto et al., 2019).
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Of note, despite the low H2O content of the parental melt of nakhlites (e.g., <100 ppm; Weis et al., 2017 and Filiberto et al., 2019), the final mineral assemblage observed here (i.e. Cl apatite, K feldspar, quartz and Fe/Mg-rich clay minerals) is typical of evolved/granitic rocks, even though it has long been argued that a significant H2O content is required to produce such rocks (Campbell and Taylor, 1983).
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Whitaker, M.L., Nekvasil, H., Lindsley, D.H., McCurry, M. (2008) Can crystallization of olivine tholeiite give rise to potassic rhyolites?—an experimental investigation. Bulletin of Volcanology 70, 417–434.
Show in contextIn fact, the presence of Cl in a magma affects its liquidus temperature and increases pyroxene stability to lower pressures as does H2O, permitting the residual melt to evolve to lower temperatures before solidification (Filiberto and Treiman, 2009a,b), eventually leading to alkali-rich/felsic compositions like those obtained from H2O-rich melts (Nekvasil et al., 2004; Whitaker et al., 2008).
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Wray, J.J., Hansen, S.T., Dufek, J., Swayze, G.A., Murchie, S.L., Seelos, F.P., Skok, J.R., Irwin III, R.P., Ghiorso, M.S. (2013) Prolonged magmatic activity on Mars inferred from the detection of felsic rocks. Nature Geoscience 6, 1013.
Show in contextOnly rare exposures of evolved rocks containing hydrated silica and/or quartz have been reported from orbit (Christensen et al., 2005; Bandfield, 2006; Carter and Poulet, 2013; Wray et al., 2013).
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Because of the presence of Fe/Mg-rich clay minerals interpreted as secondary aqueous alteration products (Gooding et al., 1991; Bridges et al., 2001; Carter and Poulet, 2013; Wray et al., 2013; Hicks et al., 2014), the rare evolved rocks detected from orbit have been interpreted as resulting from the hydrothermal alteration or diagenesis of mafic crustal materials (Smith and Bandfield, 2012; Ehlmann and Edwards, 2014).
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Similarly, some of the evolved units detected from orbit and containing Fe/Mg-rich clay minerals (Christensen et al., 2005; Bandfield, 2006; Carter and Poulet, 2013; Wray et al., 2013) may not be mafic rocks having undergone aqueous alteration processes but rather evolved/granitic materials containing primary Fe/Mg clay minerals that formed via igneous differentiation.
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