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(a) A CTX mosaic of volcano 1. The black box indicates the location of Figure 2c. The yellow dashed line marks the location of the cross‐section profile in Figure 4. (b) A geologic‐geomorphic map of volcano 1. (c) CRISM mineral parameter maps (Fe/Mg clay minerals in red, Al/Si materials in blue and hydrous minerals in green) overlaid on CTX images of volcano 1. (d) Ratioed CRISM I/F spectra containing Al/Si materials and Fe/Mg clay minerals from FRT00023521. Library spectra of Al clay minerals and Fe/Mg clay minerals are in black for comparison. Gray lines mark bands near 1.40, 1.90, 2.21, and 2.30 µm. The spectra of kaolinite, montmorillonite, opal, nontronite, and saponite are from the USGS library (Clark et al., 2007). (e) Examples of possible layer outcrop at volcano 1 are shown in the CTX image (K01_053871_1616_XI_18S059W). (f) A subset of color HiRISE image (ESP_026206_1615) shows light‐toned materials exposed in crater A, which are clay deposits filled with polygonal fracture as the white arrow indicates. (g) An enlarge figure shows the detail of the polygonal fractures of clay deposits. CRISM, Compact Reconnaissance Imaging Spectrometer for Mars; CTX, Context Imager; HiRISE, High Resolution Imaging Science Experiment.
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Compositional stratigraphy, generally composed of Al-rich clay minerals overlying Fe/Mg-rich clay minerals, is observed in many locations on Mars. Here we describe the occurrence of such mineralogical stratigraphy in settings where the protoliths are almost certainly pyroclastic materials. One such example includes altered rocks high on the summit...
Citations
... Leaching, the chemical alteration or chemical weathering of minerals by selective dissolution of elements, has long played a significant role in pedogenesis-the evolution of martian soils (Dreibus et al., 2008;Hurowitz et al., 2006;Retallack, 2014;Thorpe et al., 2021Thorpe et al., , 2022Ye & Michalski, 2021). Of special importance to near-surface processes on Mars, leaching generates fluids rich in elements that can then migrate and participate in authigenic and diagenetic mineralization over a wide range of temperatures (Bullock & Moore, 2004). ...
... Ubiquitous aqueous alteration of the martian crust has spanned billions of years of sequential, often cyclical processes that are modified by hydrothermal systems (including serpentinization), disrupted by bolide impacts, and significantly influenced by the effects of other primary and secondary chemical processes, including evaporation, precipitation, hydration/dehydration, oxidation/reduction, and leaching Arvidson et al., 2014;Bridges et al., 2015;Bristow et al., 2021;Farley et al., 2022;J. C. Liu et al., 2021;Mangold et al., 2019;McGlynn et al., 2012;Ming et al., 2009;Murchie et al., 2009;Sheppard et al., 2021;Thorpe et al., 2022;Ye & Michalski, 2021;Yen et al., 2017). Indeed, "diagenesis" is a grab bag of chemical processes that may often represent a continuum with these other modes of mineral formation. ...
A systematic survey of 161 known and postulated minerals originating on Mars points to 20 different mineral‐forming processes (paragenetic modes), which are a subset of formation modes observed on Earth. The earliest martian minerals, as on Earth, were primary phases from mafic igneous rocks and their ultramafic cumulates. Subsequent primary igneous minerals were associated with products of limited fractional crystallization, including alkaline and quartz‐normative lithologies. Significant mineral diversification occurred via precipitation of primary phases from aqueous and atmospheric fluids, including authigenesis, hydrothermal and cryogenic precipitation, and evaporites, including freeze drying during eras of low atmospheric pressures. In particular, hydrothermal mineral formation associated with both volcanic fluids and sustained hydrothermal activity in impact fracture zones may have triggered significant mineral diversification, though as yet undocumented. At least 65 such primary minerals have been identified by flown missions to Mars and from martian meteorites. A host of secondary martian minerals were produced by near‐surface processes related to water/rock interactions, including hydration/dehydration, oxidation/reduction, serpentinization, metasomatism, and a variety of diagenetic alterations. Additional mineral diversity resulted from metamorphic events, including thermal and shock metamorphism, lightning, and bolide impacts. However, several dominant sources of mineral diversity on Earth, including (a) extensive fluid/rock interactions and element concentration associated with plate tectonics; (b) high‐pressure regional metamorphism associated with plate tectonics; and (c) biologically mediated mineralization—are not known to be in play on Mars. Consequently, we estimate the total mineral diversity of Mars to be an order of magnitude smaller than on Earth.
... Typically, Fe/Mg smectites are present as a thick unit underneath Al clays (e.g., Bishop et al., 2013;Carter et al., 2015;Ye and Michalski, 2022). The stratigraphic relationship in which Al clays overlying Fe/Mg clays is observed in the Noachis Terra (e.g., Wray et al., 2009), Mawrth Vallis (e.g., Bishop et al., 2008;Wray et al., 2008;Liu et al., 2021c), Nili Fossae (e.g., Ehlmann et al., 2009), western Arabia Terra (e.g., Noe Dobrea et al., 2010), Valles Marineris (e.g., Murchie et al., 2009), Gale Crater (e.g., Bristow et al., 2018), Eridania basin (e.g., Dang et al., 2020), and Thaumasia Planum (e.g., Ye and Michalski, 2021). Occasionally, allophane and imogolite exist at the top of the above clay stratigraphy (e.g., Bishop and Rampe, 2016;Whelley et al., 2021;Ye and Michalski, 2021). ...
... The stratigraphic relationship in which Al clays overlying Fe/Mg clays is observed in the Noachis Terra (e.g., Wray et al., 2009), Mawrth Vallis (e.g., Bishop et al., 2008;Wray et al., 2008;Liu et al., 2021c), Nili Fossae (e.g., Ehlmann et al., 2009), western Arabia Terra (e.g., Noe Dobrea et al., 2010), Valles Marineris (e.g., Murchie et al., 2009), Gale Crater (e.g., Bristow et al., 2018), Eridania basin (e.g., Dang et al., 2020), and Thaumasia Planum (e.g., Ye and Michalski, 2021). Occasionally, allophane and imogolite exist at the top of the above clay stratigraphy (e.g., Bishop and Rampe, 2016;Whelley et al., 2021;Ye and Michalski, 2021). In the following, three locations with the highest contents of clay minerals are described in detail. ...
... During the Noachian period when liquid water was available, clay minerals were mainly formed by the reaction between martian basaltic crust and liquid water (e.g., Zolensky et al., 1988;Ehlmann et al., 2011b;Carter et al., 2015). Ye and Michalski (2021) considered that glassy, porous, and highly reactive materials from widespread explosive volcanism on early Mars also provided raw materials for the formation of clay minerals. The chemistry of water (pH, Eh, dissolved ions) controls the species of as-formed clay minerals. ...
Clay minerals, or analogously phyllosilicates, are some of the most astonishing minerals ever discovered on Mars due to their roles as indicators of water-rock interaction. Their types, abundances, and locations provide hints to ancient environmental conditions of Mars and to the possible places where present-day mineral-bound water and/or biosignatures are likely to be detected. In this contribution, the definition, structures, and hydrated states, the global distribution and formation mechanisms, the significance of occurrence, and the developing detection techniques of clay minerals on Mars are summarized and discussed. The definition and structure-based classification of martian clay minerals build upon their Earth analogues; some martian clay minerals contain less water in their structure and thus exhibit smaller interlayer spacings. Clay minerals on Mars have been widely detected in ancient terrains of Noachian and Early Hesperian age (>3.5 Ga) across the planet. They have been formed mainly by chemical weathering, sedimentation, and hydrothermal alteration, at the surface or in the subsurface. Many techniques, including telescopic observations from Earth, remote sensing from Mars orbiters, in-situ characterizations by Mars landers/rovers, and lab studies of martian meteorites and terrestrial analogues and geochemical modeling, have been developed to detect, identify and further understand clay minerals on Mars. Among these techniques, visible and near-infrared reflectance spectroscopy onboard orbiters is the most powerful at global or regional scales while in-situ X-ray diffraction is the most definitive at a much smaller scale. The occurrence of clay minerals on Mars provides evidence for the presence of liquid water, the evolving geological alterations under varied environments and climates, and the potential habitability. Clay minerals on their own can serve as water sources for rocket fuel, human exploration, and immigration. Although many revolutionary advances have been made on martian clay minerals, many intriguing questions remain, including but not limited to the precise identification and quantification of clay minerals, the effects of impact on the detection of clay minerals, the formation and preservation of short-range ordered clay minerals, the co-occurrence of clay minerals and other secondary minerals, and the detection of clay minerals beyond Earth and Mars.
... Terrestrial paleosols are a geological record of the atmospheric composition, climate, topography and organisms present before soil burial (Retallack, 2019). On Mars, paleosols, also known as weathering profiles, may have formed in sediments such as basaltic sand or volcanic ash that were subject to subaerial weathering by surface waters (Retallack, 2014;Amundson, 2018;Liu et al., 2021b;Ye and Michalski, 2021) and ...
Ancient, buried soils, or paleosols, may have been preserved in the geological record on Mars, and are considered high‐priority targets for biosignature investigation. Studies of paleosols on Earth that are similar in composition to putative martian paleosols can provide a reference frame for constraining their organic preservation potential on Mars. However, terrestrial paleosols typically preserve only trace amounts of organic carbon, and determining what carbon is original is complicated by diagenesis and additions of modern carbon. The objectives of this study were (a) to determine whether organic carbon in Mars‐analog paleosols can be detected with thermal and evolved gas analysis, and (b) constrain the age of organic carbon using radiocarbon (¹⁴C) dating. Oligocene (33 Ma) paleosols from Oregon were examined with an instrument similar to the Sample Analysis at Mars Evolved Gas Analysis instrument onboard the Mars Science Laboratory Curiosity rover. Trace amounts of organic carbon and fragments of organic molecules were observed in all samples. Total organic carbon (TOC) ranged from 0.002 to 0.032 ± 0.006 wt. %. The near‐surface horizons of paleosols had significantly higher TOC relative to subsurface layers. Radiocarbon dating of four samples revealed an organic carbon age of ∼6,200–14,500 years before present and a fraction modern ranging from 0.16 to 0.46. Modeled abundances of modern carbon in bulk samples ranged from 0.41%–3.1% ± 0.11%, which were consistent with additions of small amounts of modern organic carbon. This work demonstrates that martian paleosols are a potential high priority location for in‐situ biosignature investigation.
... Today the surface of Mars is frigid, wind-deflated and barren, but there is extensive geological evidence for transient warm and wet habitable surface conditions in the Noachian (4.1-3.7 Ga) period of early Mars (Bishop et al., 2008a(Bishop et al., , 2008bBishop et al., 2013;Scheller et al., 2021;Ye and Michalski, 2021). Orbital sensing of the Martian surface has revealed clay mineral deposits in thousands of locations, wherever Noachian-age terrains are not obscured by dust, sand, or overlying strata (Murchie et al., 2007;Carter et al., 2015;Loizeau et al., 2018;Franklin et al., 2021). ...
... One hypothesis for their formation is from pedogenic weathering of mafic sediments such as volcanic ash during intermittent warm periods early in Mars' history (Le Deit et al., 2012;Carter et al., 2015;Bishop et al., 2018;Liu et al., 2021a). These altered sediments have been detected at topographic highs including the summits and flanks of volcanoes which is consistent with formation in surface environments via pedogenic weathering (Ye and Michalski, 2021). Many of the clearest examples of putative weathering profiles are observed in crater rims (Horgan et al., 2012;Hays et al., 2017). ...
Ancient (4.1–3.7-billion-year-old) layered sedimentary rocks on Mars are rich in clay minerals which formed from aqueous alteration of the Martian surface. Many of these sedimentary rocks appear to be composed of vertical sequences of Fe/Mg clay minerals overlain by Al clay minerals that resemble paleosols (ancient, buried soils) from Earth. The types and properties of minerals in paleosols can be used to constrain the environmental conditions during formation to better understand weathering and diagenesis on Mars. This work examines the mineralogy and diagenetic alteration of volcaniclastic paleosols from the Eocene-Oligocene (43–28 Ma) Clarno and John Day Formations in eastern Oregon as a Mars-analog site. Here, paleosols rich in Al phyllosilicates and amorphous colloids overlie paleosols with Fe/Mg smectites that altogether span a sequence of ~ 500 individual profiles across hundreds of meters of vertical stratigraphy. Samples collected from three of these paleosol profiles were analyzed with visible/near-infrared (VNIR) spectroscopy, X-ray diffraction (XRD), and evolved gas analysis (EGA) configured to operate like the SAM-EGA instrument onboard Curiosity Mars Rover. Strongly crystalline Al/Fe dioctahedral phyllosilicates (montmorillonite and nontronite) were the major phases identified in all samples with all methods. Minor phases included the zeolite mineral clinoptilolite, as well as andesine, cristobalite, opal-CT and gypsum. Evolved H2O was detected in all samples and was consistent with adsorbed water and the dehydroxylation of a dioctahedral phyllosilicate, and differences in H2O evolutions between montmorillonite and nontronite were readily observable. Detections of hematite and zeolites suggested paleosols were affected by burial reddening and zeolitization, but absence of illite and chlorite suggest that potash metasomatism and other, more severe diagenetic alterations had not occurred. The high clay mineral content of the observed paleosols (up to 95 wt%) may have minimized diagenetic alteration over geological time scales. Martian paleosols rich in Al and Fe smectites may have also resisted severe diagenetic alteration, which is favorable for future in-situ examination. Results from this work can help differentiate paleosols and weathering profiles from other types of sedimentary rocks in the geological record of Mars.
Nonmarine rocks in sea cliffs of southern California store a detailed record of weathering under tropical conditions millions of years ago, where today the climate is much drier and cooler. This work examines early Eocene (~ 50-55 million-year-old) deeply weathered paleosols (ancient, buried soils) exposed in marine terraces of northern San Diego County, California, and uses their geochemistry and mineralogy to reconstruct climate and weathering intensity during early Eocene greenhouse climates. These Eocene warm spikes have been modeled as prequels for ongoing anthropogenic global warming driven by a spike in atmospheric CO 2. Paleocene-Eocene thermal maximum (PETM, ~ 55 Ma) kaolinitic paleosols developed in volcaniclastic conglomerates are evidence of intense weathering (CIA > 98) under warm and wet conditions (mean annual temperature [MAT] of ~ 17 °C ± 4.4 °C and mean annual precipitation [MAP] of ~ 1500 ± 299 mm). Geologically younger Early Eocene climatic optimum (EECO, 50 Ma) high shrink-swell (Vertisol) paleosols developed in coarse sandstones are also intensely weathered (CIA > 80) with MAT estimates of ~ 20 °C ± 4.4 °C but have lower estimated MAP (~ 1100 ± 299 mm), suggesting a less humid climate for the EECO greenhouse spike than for the earlier PETM greenhouse spike.
Nonmarine rocks in sea cliffs of southern California store a detailed record of weathering under tropical conditions millions of years ago, where today the climate is much drier and cooler. This work examines early Eocene (50-55 million-year-old) deeply weathered paleosols (ancient, buried soils) exposed in marine terraces of northern San Diego County, California, and uses their geochemistry and mineralogy to reconstruct climate and weathering intensity during early Eocene greenhouse climates. These Eocene warm spikes have been modeled as prequels for ongoing anthropogenic global warming due to atmospheric CO2. Paleocene-Eocene thermal maximum (PETM, ~55 Ma) kaolinitic paleosols developed in volcaniclastic conglomerates are evidence of intense weathering (CIA >98) under warm and wet conditions (mean annual temperature [MAT] of ~17° C ± 4.4° C and mean annual precipitation [MAP] of ~1920 ± 182 mm). Geologically younger Early Eocene climatic optimum (EECO, 50 Ma) high shrink-swell (Vertisol) paleosols developed in coarse sandstones are also intensely weathered (CIA >80) with MAT estimates of ~20 °C ± 4.4° C but have lower estimated MAP (~1500 ± 108 mm), suggesting a less tropical climate for the EECO greenhouse spike than for the earlier PETM greenhouse spike.
Chemical weathering profiles on Mars which consist of an upper Al clay-rich, Fe-poor layer and lower Fe/Mg clay-rich layer are believed to have formed due to precipitation-driven top down leaching process in an ancient, reducing greenhouse climate. Here we use remote sensing imagery and spectroscopy coupled with topographic data and crater chronology to explore the geological characteristics, stratigraphy and relative age of >200 weathering profiles across the southern highlands of Mars. We find that nearly all exposures show a similar, single stratigraphic relationship of Al/Si materials over Fe/Mg clays rather than multiple, interbedded mineralogical transitions. This suggests either one single climate warming event or, perhaps more likely, chemical resetting of weathering horizons during multiple events. While the time required to form a typical martian weathering profile may have been only ∼10⁶−10⁷ years, the profiles occur in deposits dating from the Early Noachian into the Hesperian and suggest that chemical weathering may have occurred over a large range of geologic time, with a peak around 3.7–3.8 billion years ago.
The persistence of soil organic carbon (C) in soil, defined as the mean residence time of organic C compounds in soils, is a critical measure for understanding the capacity of terrestrial ecosystems to regulate biogeochemical cycles. The persistence of organic carbon in soil is most often considered at timescales ranging from tens to thousands of years, but the study of organic C in paleosols (i.e., ancient, buried soils) suggests that buried soils may have the capacity to preserve organic compounds for tens of millions of years. A quantitative assessment of C sources and sinks from these ancient terrestrial landscapes is complicated by additions of modern organic C, primarily due to the infiltration of dissolved organic carbon. In this study, we quantify total organic C content and radiocarbon activity in samples collected from 28- to 33-million-year-old paleosols that are naturally exposed as unvegetated badland outcrops near eastern Oregon’s “Painted Hills”. The study site is part of a well-mapped ~400-meter-thick sequence of Eocene-Oligocene (45-28 Ma) volcaniclastic paleosols, and thus we expected to find “radiocarbon dead” samples preserved in deep layers of the lithified, brick-like exposed outcrops. Total organic C, measured in three individual profiles spanning depth transects from the outcrop surface to a 1-meter depth, range from 0.01 - 0.8 wt. % with no clear C-concentration or age-depth profile. Ten radiocarbon dates from the same profiles reveal calibrated radiocarbon ages of ~11,000 – 30,000 years BP that unexpectedly indicate additions of recent and /or modern organic C. A two-endmember mixing model for radiocarbon activity suggests that modern C may compose ~0.5-3.5% of the total organic carbon pool preserved in these ancient landscapes. We discuss several mechanisms by which modern organic C could have infiltrated into the lithified, brick-like paleosol surfaces and discuss potential implications for future research of ancient soils.
Abstract Martian dust simulant (i.e., a terrestrial substitute for Martian dust) is the basis for experimentally investigating the properties of Martian dust and its effects on Mars exploration activities. In this study, we reported a new Martian dust simulant (Jining Martian Dust Simulant, called JMDS‐1), which was prepared based on terrestrial Jining basalt (90 wt%) and other mineral phases (i.e., 2 wt% magnetite, 2 wt% hematite, 2 wt% anhydrite, 2 wt% calcite, and 2 wt% kaolin). Measurements of JMDS‐1 dust simulant show that JMDS‐1 has a bulk composition, mineralogy, reflectance spectra, and particle characteristics similar to the Martian dust detected by Mars rovers. In addition, we measured the thermal conductivity of dust simulant, soil simulant, and dust‐soil simulant mixtures under simulated Martian conditions (i.e., −30°C; 500–1,000 Pa). The results reveal that the micro‐sized dust simulant has a thermal conductivity of ∼0.015 W/mK, which is two times lower than the thermal conductivity of sub‐millimeter sized soil simulant (i.e., ∼0.035 W/mK). This implies that the dust layer on Mars seems to play a significant role to change the thermal properties of surface materials.
