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Icarus

Volume 384, 15 September 2022, 115090
Icarus

Clay sediments derived from fluvial activity in and around Ladon basin, Mars

https://doi.org/10.1016/j.icarus.2022.115090Get rights and content

Abstract

The morphology and mineralogy of light-toned layered sedimentary deposits were investigated using multiple orbital datasets across the Ladon basin region, including within northern Ladon Valles, southern Ladon basin, and the southwestern highlands of Ladon basin. Light-toned layered deposits are particularly widespread in Ladon Valles and Ladon basin, ranging laterally for distances over 200 km, with the thickest exposure (54 m) located at the mouth of Ladon Valles. The restriction of layered sediments below a common elevation (−1850 m) in Ladon Valles and Ladon basin and their broad conformable distribution with bedding dips between 1 and 4° favor a lacustrine environment within this region during the Late Noachian to Early Hesperian. The Ladon layered deposits have spectral signatures consistent with Mg-smectites, even when the morphology of the layering varies considerably in color and brightness. These phyllosilicates were most likely eroded from the highlands upstream to the south, but the lacustrine environment may have also been favorable for in situ alteration and formation of clays. The southwestern highlands also display light-toned layered deposits within valleys and small basins. These sediments predominantly have signatures of Mg-smectites, although we also identified Fe/Mg-smectites and additional hydrated phases in some deposits. One of these altered deposits was found within a younger Holden crater secondary chain, possessing a Late Hesperian to Early Amazonian age for valleys and sediments that postdate the deposits within Ladon Valles and Ladon basin. Phyllosilicate signatures were also detected in the ejecta from two fresh craters that exposed highland materials upstream of Arda Valles, revealing that the highlands are clay-bearing and may be the most plausible source of the clay-bearing fluvial-derived sediments found within the valleys and basins downstream. Some of the highland deposits are likely coeval to similar clay-bearing sediments found to the south within Holden and Eberswalde craters, indicating late, widespread fluvial activity and deposition of allochthonous clays within the broader Margaritifer Terra region when Mars was thought to be colder and drier.

Introduction

The informally named Ladon basin and surrounding region in Margaritifer Terra host exceptionally numerous, well-preserved fluvial landforms and basin stratigraphy, which includes clay-bearing (containing phyllosilicates and associated altered components) deposits (Milliken and Bish, 2010). Some of the best-developed exposed fluvial landforms and basin stratigraphy on Mars are found within Margaritifer Terra (e.g., Grant, 2000; Grant and Parker, 2002), making it an ideal region to test local and regional source-to-sink pathways of sediments deposited by multiple processes under changing environmental conditions over time. Ladon basin (Fig. 1) is a large multi-ringed impact basin (centered near 17.8°S, 330.4°E) that is partly overprinted by the slightly younger Holden multi-ringed basin to the southwest (centered near 26.0°S, 325.8°E) (Schultz et al., 1982; Grant, 1987). Both the Ladon and Holden basin impacts formed prior to ~3.7–3.9 Ga (Irwin III and Grant, 2013) and are perhaps as old as 4.17 Ga when the martian dynamo was still active (Lillis et al., 2013). Both Ladon and Holden basins lie along the segmented Uzboi, Ladon, and Morava (ULM) mesoscale outflow system, which formed during the Late Noachian through Early Hesperian by flooding sourced from the Argyre basin (Grant and Parker, 2002; Irwin III and Grant, 2009; Irwin III and Grant, 2013). The present topographic expression of Ladon basin is ringed by relief/mountains (e.g., Schultz et al., 1982) that have shed sediments via a well-developed radial centripetal network of valleys (e.g., Arda Valles).

Incision of Ladon Valles likely occurred during multiple large discharge events (Boothroyd, 1983; Grant and Parker, 2002; Irwin III and Grant, 2013) from filling and overflowing of Holden basin. The discharges from Holden basin were so large that the pre-valley topography could not initially confine the flow(s) into a single channel. The hanging side channels and the main stem suggest that multiple overflow points remained active until the central one was incised deeply enough to confine the entire flow. These observations are consistent with at least five distinct terraces along Ladon Valles (Boothroyd, 1983; Grant, 1987; Grant and Parker, 2002; Parker and Pieri, 1985). Discharge estimates during incision of the ULM system are somewhat uncertain, but the elevation of terraces along Ladon Valles, combined with channel cross section dimensions and gradients, suggest discharge rates between 150,000 m3/s and 450,000 m3/s relatively late in the flood when the flow was confined to a single channel (Grant and Parker, 2002). If these estimates are accurate, significant flows are associated with the formation of the ULM mesoscale outflow system and evolution of Ladon basin. Fluvial valley network systems formed during the Late Noachian to Early Hesperian and dissected much of the highlands in the Ladon region as water flowed downslope into Ladon basin, producing Arda Valles and other valley systems in the highlands (Irwin III and Grant, 2013; Weitz et al., 2022). The lack of fluvial deposits at the mouth of Arda Valles and on the floor of Ladon basin where these valleys terminate (Weitz et al., 2022) indicates either that the sediments were buried by younger basin units, removed by later erosion, or thinly distributed across the Ladon basin floor.

Within Ladon Valles and Ladon basin, extensive light-toned (where “light-toned” is defined with respect to other features in the images rather than due to absolute albedo) layered deposits containing phyllosilicate signatures have been identified (Milliken and Bish, 2010; Weitz and Bishop, 2012; Weitz et al., 2013). Other nearby phyllosilicate-bearing layered outcrops to the south of Ladon with broadly similar morphology occur in Holden and Eberswalde craters (Pondrelli et al., 2005, Pondrelli et al., 2008; Lewis and Aharonson, 2006; Grant et al., 2008; Milliken and Bish, 2010; Rice et al., 2011). Individual beds in the phyllosilicate-bearing deposits of Ladon, Holden, and Eberswalde are often less than a meter thick, can be traced for hundreds of meters, and do not appear to truncate one another (Grant et al., 2008). The deposits are mostly confined to low elevations, do not drape exterior surfaces, and there are no remnants occurring at higher elevations, thereby favoring low-energy alluvial or lacustrine deposits rather than airfall materials like volcanic ash (Malin and Edgett, 2003; Grant et al., 2008; Irwin III and Grant, 2013). The clays within Ladon Valles and Ladon basin could be associated with laterally extensive phyllosilicate-bearing terrains identified to the north in Margaritifer Terra (Seelos et al., 2016), Xanthe Terra and in the walls and plains surrounding Valles Marineris (Le Deit et al., 2012), and northwest Noachis Terra to the south (Buczkowski et al., 2010). Additional clays found in Margaritifer Terra by Thomas et al. (2017) suggest that some of these aqueous alteration products could have formed by fluids released in fractures, thereby providing potentially habitable environments. Because the phyllosilicate signatures at Ladon Valles are associated with finely layered sedimentary deposits, aqueous conditions during deposition and (or) in the source regions prior to erosion and transport may have been favorable for past habitability.

In this study, we analyzed data from several different orbital instruments acquired of Ladon basin, northern Ladon Valles, and the western highlands of Ladon basin to search for and characterize light-toned layered deposits containing phyllosilicate spectral signatures that could indicate sedimentary materials representative of habitable environments within this region of Margaritifer Terra. The morphology, mineralogy, and stratigraphy of the light-toned phyllosilicate-bearing deposits were used to decipher how the deposits may have formed, which is critical to understanding the aqueous and climatic history of the Margaritifer Terra region. We first discuss the deposits observed in Ladon Valles and Ladon basin, followed by smaller deposits identified within the southwestern highlands of Ladon basin. A sequence and timing of events within the study region is later described that postulates how the phyllosilicate-bearing deposits in each location most likely formed.

Section snippets

Data products

Orbital data collected by the Mars Global Surveyor (MGS), Mars Odyssey (ODY), Mars Express (MEX), and Mars Reconnaissance Orbiter (MRO) spacecraft were analyzed in this study. Data from the MGS Mars Orbiter Laser Altimeter (MOLA, see Zuber et al., 1992) and Mars Odyssey Thermal Emission Imaging System (THEMIS, see Christensen et al., 2004) were combined with newer views at higher spatial and spectral resolution provided by the Mars Express High Resolution Stereo Camera (HRSC) (Jaumann et al.,

Morphology and stratigraphy

The light-toned layered clay-bearing deposits extend from northern Ladon Valles into southern Ladon basin, covering more than 200 km in areal extent (Fig. 1b). The continuous deposit in Ladon Valles is concentrated on the eastern side, but smaller outliers are also visible along the western side (Fig. 2). The best exposures of layering occur along the sloping edge of the deposit where an overlying dark mantle obscures the flat upper surfaces. The deposit was laid down on the relatively smooth,

Discussion

This study determined that the light-toned layered deposits found within Ladon Valles, Ladon basin, and in the highlands adjacent to southwestern Ladon basin contain primarily Mg-smectites, with Fe/Mg-smectites and ferrihydrite in some areas. The light-toned layered deposits in the highlands occur either within valleys or small basins that were fed by valleys. These highland geologic settings are probably similar as they all occur within the same geologic unit (e.g., Terra unit mapped by Irwin

Conclusions

Phyllosilicates occur within light-toned layered deposits found in the southwestern highlands of Ladon basin, southern Ladon basin, and northern Ladon Valles. The sediments within these deposits were derived from erosion of the clay-bearing Noachian highlands unit upstream and were transported by valleys and channels that later deposited the sediments downstream. In the highlands, these valley systems deposited the clay assemblages within small basins or blocked valley systems along the

Declaration of Competing Interest

None.

Acknowledgements

This work was funded from MDAP grant 80NSSC17K0505 (CW and JB) and PGG grant NNX13AM81G (CW, JG, SP, RI). We would like to thank Melissa Rice and an anonymous reviewer for their very helpful comments that improved the quality of this manuscript. All HiRISE camera images used in this study are publicly available at https://hirise-pds.lpl.arizona.edu/PDS/. All CRISM images are available at this website: http://crism-map.jhuapl.edu/. All CTX images are available at this website: //viewer.mars.asu.edu/viewer/ctx#T=0

References (73)

  • V.R. Baker

    High-energy megafloods: planetary settings and sedimentary dynamics

  • J.L. Bandfield et al.

    A global view of Martian surface compositions from MGS-TES

    Science

    (2000)
  • J.L. Bishop et al.

    Spectroscopic and Geochemical Analyses of Ferrihydrite from Springs in Iceland and Applications to Mars

  • J.L. Bishop et al.

    Reflectance and emission spectroscopy study of four groups of phyllosilicates: Smectites, kaolinite-serpentines, chlorites and micas

    Clay Miner.

    (2008)
  • J.L. Bishop et al.

    Phyllosilicate diversity and past aqueous activity revealed at Mawrth Vallis, Mars

    Science

    (2008)
  • J.L. Bishop et al.

    Implementing New Feature Extraction Techniques for Characterization of Complex Mineral Signatures of Salty Regions on Mars, In IGARSS - 2020 IEEE International Geoscience and Remote Sensing Symposium

    (2020)
  • J.L. Bishop et al.

    Correlating sulfates with the aqueous geochemical history at Juventae Chasma, Mars

  • J.C. Boothroyd

    Fluvial drainage systems in the Ladon Basin area: Margaritifer sinus area, Mars

    Geological Society of America Abstract Programs

    (1983)
  • D.L. Buczkowski et al.

    Extensive phyllosilicate-bearing layer exposed by valley systems in North-West Noachis Terra

  • S.F.A. Cartwright et al.

    New Ring Structure Estimates of Ladon Basin, Mars, from Mafic Mineral Mapping with CRISM, in 50th Lunar Planet. Sci. Conf., Abstract 2755

    (2019)
  • J.C. Cawley et al.

    Evolution of escarpments, pediments, and plains in the Noachian highlands of Mars

    J. Geophys. Res.

    (2018)
  • P.R. Christensen et al.

    The thermal emission imaging system (THEMIS) for the Mars 2001 Odyssey Mission

    Space Science Reviews

    (2004)
  • A.W. Delamere et al.

    Color imaging of Mars by the high resolution imaging science experiment (HiRISE)

    Icarus

    (2010)
  • A.A. Fraeman et al.

    The stratigraphy and evolution of lower Mount Sharp from spectral, morpholo-gical, and thermophysical orbital data sets

    J. Geophys. Res. Planets

    (2016)
  • I.J. Goodfellow et al.

    Generative Adversarial Nets

    arXiv:1406.2661v1

    (2014)
  • J.A. Grant

    The geomorphic evolution of eastern Margaritifer sinus, Mars in advances in planetary geology

    NASA Technical Memorandum

    (1987)
  • J.A. Grant

    Valley formation in Margaritifer sinus, Mars, by precipitation-recharged ground-water sapping

    Geology

    (2000)
  • J.A. Grant et al.

    Drainage evolution of the Margaritifer sinus region, Mars

    J. Geophys. Res.

    (2002)
  • J.A. Grant et al.

    Degradation of selected terrestrial and martian impact craters

    J. Geophys. Res.

    (1993)
  • J.A. Grant et al.

    HiRISE imaging of impact megabreccia and sub-meter aqueous strata in Holden crater

    Mar. Geol.

    (2008)
  • R.P. Irwin et al.

    Chapter 11: Large basin overflow floods on Mars

  • R.P. Irwin et al.

    Geologic map of MTM -15027, −20027, −25027 and −25032 quadrangles, Margaritifer Terra region of Mars, U.S. Geological Survey Scientific Investigations Map 3209, scale 1:1,000,000

    (2013)
  • R. Jaumann

    The high-resolution stereo camera (HRSC) experiment on Mars express: instrument aspects and experiment conduct from interplanetary cruise through the nominal mission

    Plan. Space Sci.

    (2006)
  • R.L. Kirk et al.

    Ultrahigh resolution topographic mapping of Mars with MRO HiRISE stereo images: meter-scale slopes of candidate Phoenix landing sites

    J. Geophys. Res.

    (2008)
  • L. Le Deit et al.

    Extensive surface pedogenic alteration of the Martian Noachian crust suggested by plateau phyllosilicates around Valles Marineris

    J. Geophys. Res.

    (2012)
  • K.W. Lewis et al.

    Stratigraphic analysis of the distributary fan in Eberswalde crater using stereo imagery

    J. Geophys. Res.

    (2006)
  • Cited by (4)

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