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. 2024 Dec 19;129(12):e2024JE008425. doi: 10.1029/2024JE008425

Mapping of Western Valles Marineris Light‐Toned Layered Deposits and Newly Classified Rim Deposits

Ivan G Mishev 1,✉, Isaac B Smith 1,2, Cathy Quantin 3, Patrick Thollot 4, Nathaniel E Putzig 2, Christina Viviano 5, Matt Chojnacki 2, Bruce Campbell 6
PMCID: PMC11659652  PMID: 39712871

Abstract

Layered deposits are found on the plateaus surrounding the western portion of Valles Marineris, mantling the chasmata rims. These rim deposits exhibit intricate layering and are described as light‐toned layered deposits (LLDs) in previous studies. Light‐toned layered deposits are thought to be composed of pyroclastic ash that was emplaced during volcanic eruptions and later chemically altered. Using Shallow Radar (SHARAD) observations to map radar reflections from what appears to be the base of these deposits, we discovered two additional types of rim deposits that are contiguous with the well‐known LLDs; weakly layered deposits (WLDs) that exhibit less obvious stratification and completely unstratified deposits designated as nonlayered deposits (NDs). Complementing the SHARAD data with imagery from Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment (HiRISE) and Context Camera (CTX) and with narrow‐angle imagery from the Mars Global Surveyor Mars Observer Camera (MOC‐NA), we mapped the full extent of all rim deposits and present the finished map within this study. We hypothesize that all three deposits originate from pyroclastic ashfall but experienced different degrees of modification due to the variable presence of liquid water. This hypothesis requires a source of volcanic depositional material and past aqueous environments in regions with LLDs and WLDs. We discuss the potential for several large Tharsis volcanoes and a hypothesized degraded volcano within Noctis Labyrinthus as sources of the ash, and we examine the evidence for past aqueous environments.

Keywords: SHARAD, radar, Valles Marineris, volcano, layered deposits, noctis

Key Points

  • Light‐toned layered deposits (LLD) on the plateaus of Valles Marineris show clear basal reflections when examined using the Shallow Radar (SHARAD)

  • Basal reflections extend past the LLD bounds, revealing two new visually distinct rim deposits on the plateaus that are contiguous with LLD

  • We hypothesize these deposits originate from pyroclastic ashfall and were subsequently altered by the variable presence of liquid water

1. Introduction

The plateaus adjacent to the rim of western Valles Mariners (VM) chasmata exhibit evidence of sedimentary deposition in lacustrine and fluvial environments (Malin & Edgett, 2001). Features such as light‐toned layered deposit (LLD), interior layered deposits, inverted channels, and dendritic valleys are found atop the plateaus and within the chasmata themselves (Le Deit et al., 2010; Mangold et al., 2004; Quantin et al., 2005; Weitz et al., 2008, 2010). This work focuses on the LLDs, which are found in various locations uniquely situated atop the plateaus that extend away from the rim (Figure 1) (Le Deit et al., 2010; Weitz et al., 2008, 2010). Light‐toned layered deposits display characteristics of sedimentary deposits overlying the Hesperian volcanic plains that form the canyon's rims and surrounding plateaus (McCauley, 1978; Scott & Tanaka, 1986; Whitbeck et al., 1991). These LLDs exhibit intricate fine‐scale stratification of lighter and darker layers, discernible at meter‐scale resolutions (Le Deit et al., 2010, 2012; Milliken et al., 2008; Weitz et al., 2008, 2010), as observed by the Mars Reconnaissance Orbiter (MRO) High‐Resolution Imaging Science Experiment (HiRISE) (McEwen et al., 2007).

Figure 1.

Figure 1

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(a) Map of rim deposits in Western Valles Marineris. Opaque (brighter) colors indicate validated units that are confirmed by Shallow Radar and visual imagery. Translucent (darker) colors indicate potential unit expansion regions, classified by limited radar and visual evidence. White lines indicate ground tracks of radargrams in Figures 2 and 5. Blue lines denote observed basal reflections. Black boxes denote footprints for HiRISE images in Figure 3. White boxes delineate location of Figures 5a and 7. Base map is Mars Odyssey Thermal Emission Imaging System Daytime Infrared (THEMIS Day IR) mosaic (Christensen et al., 2004). (b) 3D rendering of the area with THEMIS Day IR mosaic, using Mars Orbiter Laser Altimeter (MOLA) elevation (Smith et al., 2001), with a vertical exaggeration of 15, to show the topography of the proposed Noctis Mons volcano and locations of the mapped deposits with respect to important topographic features.

The depositional mechanism and morphological history of the LLDs are poorly understood. Previous investigators proposed that the LLDs are airfall deposits of pyroclastic ash arising from Tharsis volcanic activity sometime in the Late Hesperian period (Le Deit et al., 2010; Weitz et al., 2008, 2010). Light‐toned layered deposits were later altered by aqueous environments, as evidenced by the associated channel systems and valley networks and their fine‐scale layering (Weitz el al. 2008). Examinations of the LLDs using the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) (Murchie et al., 2007) identified spectra that indicate the presence of hydrated silicas, phyllosilicates, and jarosite, which are all minerals consistent with alteration and leaching in an aqueous environment (Bishop et al., 2009; Milliken et al., 2008). We hypothesize that the water originates from precipitation and/or the melting of ice within the region, following Le Deit et al. (2010).

Individual LLD strata have been shown to range from 1 to 10 m in thickness (Le Deit et al., 2010; Weitz et al., 2010), and deposits can reach tens of meters thick. The LLDs are widespread across the plateaus adjacent to the VM, and individual LLDs can extend for 100 of kilometers. However, previous mapping efforts relied on data from CRISM, HiRISE, and the Context Camera (CTX) (Bell et al., 2013; Malin et al., 2007) and were limited to surface exposures of the LLD outcrops and the limited spatial coverage available in 2010 (Le Deit et al., 2010; Weitz et al., 2008, 2010).

In this paper, we expand upon the previously mapped boundaries of the LLDs using data from the Shallow Radar (SHARAD) sounder (Seu et al., 2007) in conjunction with recent data available from multiple optical instruments, such as HiRISE, CTX, and the Mars Observer Camera (MOC) (Malin et al., 1992). We report two additional varieties of rim deposits that appear visually distinct from the LLDs but are contiguous with one another and the LLDs when examined using SHARAD. Unlike with shorter‐wavelength remote sensing, SHARAD detects a reflection from what appears to be the base of these units even when they are buried by mantling deposits or lack distinctive layered characteristics typically identified in high‐resolution imagery.

These results are further discussed in the context of various formation scenarios that describe the regional landscape evolution and role of water. We hypothesize that the LLD and the two newly identified plateau rim deposits originate from pyroclastic ashfall, having experienced differing histories with varying aqueous settings. Tharsis volcanism is considered a plausible source for pyroclastic deposition, and we examine the evidence for aqueous environments.

2. Data and Methods

2.1. Shallow Radar Data

SHARAD emits chirped radio signals downswept from 25 to 15 MHz and records the amplitude and time delay of returned signals. At the Martian surface, SHARAD has a 3–6 km horizontal resolution that is improved to 0.3–1 km in the along‐track direction through Doppler focusing (Seu et al., 2004, 2007). Nominally, SHARAD's 15 m freespace vertical resolution improves to 1/ε′, where ε' is the dielectric permittivity of a geologic material, ranging from 1 for air to ∼12 for dense basalts (Campbell & Ulrichs, 1969; Ulaby et al., 1988), but vertical resolution is then degraded by a factor of ∼2 in the suppression of sidelobes using a Hann windowing function (Nunes & Phillips, 2006). SHARAD probes to depths up to hundreds of meters, depending on the attenuation and scattering characteristics of the geologic material.

SHARAD has extensive spatial coverage in the western VM region, with over 900 individual observations (Putzig et al., 2024). Details of the SHARAD data used in this study are provided in the reference repository (Mishev, 2024b). SHARAD data were converted to a SEG‐Y format for analysis using the geophysical mapping software SeisWare™, wherein we traced each subsurface reflection and then georeferenced them for comparison with visible imagery. The geolocated positions of the reflectors were imported into JMARS (Christensen et al., 2009) to compare with optical surveys of the region.

In regions with rough local surface topography relative to the 15 m wavelength of the radar instrument, undesired off‐nadir returns, classified as clutter, may arise and interfere with or be mistaken for reflections from subsurface interfaces. To mitigate false positive detections of subsurface interfaces, “cluttergram” simulations based on Mars Orbiter Laser Altimeter (MOLA) data (Smith et al., 2001) were used to differentiate true reflections from clutter (Choudhary et al., 2016; Christoffersen et al., 2021, Figure 2).

The plateaus surrounding VM offer an ideal use scenario for SHARAD, as the high, relatively flat terrain generates far less clutter compared to rough terrain. However, at some locations, radar data suffer from slope‐derived clutter, and we rely more heavily on imagery. Clutter is also an issue in areas of high relative surface roughness, near or within the chasmata, craters, outflow channels, or tributary canyons. Because of this limitation, positively identifying thinner deposits or deposits near those features proved difficult. In an effort to avoid false positives, a conservative approach was taken when tracking reflections. This resulted in some regions that contained LLDs identified from surface mapping to be without identified radar detections.

2.2. HiRISE, CTX, MOC‐Narrow Angle Imagery

The HiRISE instrument onboard the MRO returns the highest resolution images available of the Martian landscape (McEwen et al., 2007). With image resolution of 0.25 to 0.5 m/pixel, HiRISE is able to resolve the fine layer structure of the LLD strata. In locations with poor HiRISE coverage, MOC‐NA data was used. MOC‐NA has a resolution range of 1.4–11 m/pixel, with most data ranging within 3–6 m/pixel. The high resolution of these instruments is integral in resolving meter‐scale layers and distinguishing between various surface morphologies (Figure 4).

Figure 4.

Figure 4

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(a) CTX mosaic of the Echus Chasma southern rim, with shallow valleys, dendritic channels, tributary canyons, and layers highlighted. (b) HiRISE image of LLDs near the Echus Chasma rim. Terraced layers highlighted.

Spatial coverage for high resolution imagery is relatively sparse. To supplement the higher resolution imagery, CTX was used. The 5–6 m per pixel global mosaic (Dickson et al., 2024) was too coarse to resolve the LLDs at their margins; as such, CTX is used sparingly, mainly for context, and not to determine the exact borders of the different units. Lists of all images examined in this study are provided in the reference repository (Mishev, 2024a).

We present a map in Figure 1 that expands on the results of Le Deit et al. (2010) and is based on our multi‐instrument approach. This allows for redundancy and an ability to bridge information gaps. However, lower confidence regions persist. To indicate those, we map them in Figure 1 with a more transparent fill.

3. Mapping Results

3.1. SHARAD Mapping Results

We took advantage of the dense SHARAD coverage in western VM to examine the previously mapped LLDs and found that SHARAD subsurface reflections are abundant in these locations (Figures 1 and 2a). The vast unbroken stretches of LLDs that were previously mapped with visual data are accompanied by the largest concentration of basal radar reflections. We find that such reflections extend well beyond the past LLD boundaries and into locations where LLDs are absent. We report a few sections of LLD regions without basal reflections that can be attributed to interference from clutter, such as areas surrounding large impact craters. The clutter in such areas raises the noise level to a point where confidently delineating basal reflections is not possible. It should be noted that the isolated area located at the south‐west corner of Melas Chasma has no basal reflections but is still labeled as an LLD. This lack of reflections was expected and is due to the rough and sloped terrain of this region that renders SHARAD ineffective. This region was classified as an LLD by Le Deit et al. (2010) based on visual and spectral analysis, and is kept in the new mapping, despite a lack of SHARAD reflections.

Figure 2.

Figure 2

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SHARAD radargrams (top) and corresponding clutter simulations (bottom) of three observations with ground tracks indicated in Figure 1. White bars indicate two‐way time delay. Arrows highlight basal reflections of different rim deposits, which are absent in the clutter simulations. Triangles indicate clutter. (a) Newly mapped LLD on plateau south of Echus Chasma. (b) Weakly layered deposit on the plateau north of Ius Chasma. (c) Reflector in a previously mapped LLD on the plateau south of Ius Chasma.

Figure 2 shows examples of subsurface reflections in three seperate radargrams, each produced from observations over one of the three plateaus mapped in this study. Basal reflections are displayed with arrows matching their corresponding unit color from Figure 1. The complete radar mapping (Figure 1) reveals that the rim deposits are contiguous with one another and abut or grade into each other. Further, they are consistently found only within 100 km of the canyon rims. Upon inspection, the radar reflections at the expanded areas are indistinguishable from the LLD‐associated reflections; regionally, they maintain consistent strength of return and approximate time delays to within 0.25 μs two‐way time.

3.2. Surface Morphology of Rim Deposits

3.2.1. Light‐Toned Layered Deposits (LLDs)

LLDs consist of complex friable layers that lack cross bedding across vast unbroken stretches (Figures 3a and 3d) (Le Deit et al., 2010; Weitz et al., 2008, 2010). Various landforms are spatially associated with LLDs, such as polygonal fractures, sinuous ridges, and superposed bedforms (Figures 5d and 5e), such as transverse aeolian ridges (TARs), deltoids, and crater‐associated deltoids that accumulate on the downwind side of crater rims (we call “bearded craters,” Figures 3g–3i) (Geissler, 2014; Runyon et al., 2021). They tend to be concentrated near tributary amphitheater‐headed canyons, as seen in Figure 1, that have been attributed to groundwater sapping (Kochel & Piper, 1986) or other fluvio‐lacustrine processes discussed in Section 4.1. This is particularly apparent at the Louros Valles canyon system (Figure 1). Evidence of fluvial morphologies and overland flows such as: dendritic channels, outflow valleys, sinuous ridges, and spectrally determined aqueous minerals exists in these regions (Le Deit et al., 2010 and references therein). These deposits are predominantly situated near the chasma rim, where they progressively thin and diminish with increasing distance from the edge. LLDs are primarily located in areas that slope gently downward toward the rim, suggesting a connection between topography, deposition, and modification (Figure 1b).

Figure 3.

Figure 3

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HiRISE RED map‐projected images that correspond to where SHARAD detects basal reflections. (a) LLD on the plateau south of Ius Chasma displaying intricate layering, enlarged in panel (d). (b) Weakly layered deposit on plateau north of Ius Chasma, showing less‐distinct layering isolated at outcrops along the plateau rim, enlarged in panel (e). (c) Nonlayered deposits that contain SHARAD basal reflections throughout but no visible surficial layering, enlarged in panel (f). This region appears to soften when compared to other regions, but otherwise identification is impossible without the use of radar. (g–i) Aeolian bedforms and other deposits found on the plateaus of VM where SHARAD detects basal reflections: (g) TARs. (h) Deltoids of various sizes. (i) Crater‐associated deltoid deposits (“bearded craters”) found nearby to image (g). Notice material build up within the crater as well as on the downwind side. Sizes of all occurrences vary greatly. All instances of TARs and deltoids contain evidence of abrasion in the scalloped and faceted lee slope typical of erosion.

Figure 5.

Figure 5

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(a) Enlarged region delineated in Figure 1 (THEMIS Day IR), showing the three rim deposits neighboring one another. The SHARAD track denoted by the white and blue lines in panels (a, b), crosses all three deposits. (b) The SHARAD basal reflection and corresponding cluttergram is highlighted with arrows. MOC‐NA Image (c) and HiRISE images (d, e) demonstrate NDs, LLDs, and WLDs, respectively.

Layered deposits exposed on the plateau south of Echus Chasma are visually distinct from the typical LLD found on the plateaus north and south of Ius Chasma, but possess several similarities that led to the classification as an LLD: terraced layer morphology that is most prominent along the plateau rim and thins as it extends inland (Figure 4), smooth terrain, abundances of TARs and deltoids, the regional association with large tributary canyon systems, and large concentrations of basal reflections. They also express fluvial characteristics such as dendritic or shallow channels, sinuous ridges, and inverted channels (Figure 4a) (Mangold et al., 2008). The layers on the plateau south of Echus Chasma lack the light and dark banding typical of LLDs, but despite some dissimilarities in appearance and layer intricacy, the observed layers suggest a closer relationship with LLDs than to the other deposits identified and discussed below. Consequently, we interpret these layers as LLDs.

3.2.2. Weakly Layered Deposits (WLDs)

Radar detections extend beyond the LLDs into a unit we call weakly layered deposits (WLDs). WLD basal reflections cover less area than in the LLDs but are otherwise indistinguishable from echoes seen in the LLDs. Basal reflections associated with these deposits extend inward from the canyon rim for 20–30 km on the plateaus surrounding Ius Chasma. HiRISE and CTX images show that WLDs display intermittent layering, often concentrated at outcrops directly adjacent to the rims of the plateaus on near graben/crater cliffsides where mass wasting events have exposed the layers. The visually exposed layers only extend plateau‐ward for hundreds of meters, as opposed to the LLD that are often continuous for 10 of kilometers. They display less apparent albedo contrast in their stratification than LLDs. Like the LLDs, WLDs often have associated surface morphologies such as TARs, deltoids, and crater‐associated deltoids (Figures 3b–3e, and 3g–3i) and display evidence of fluvial morphologies near tributary canyons. The evidence for a fluvio‐lacustrine reworking in these deposits is present but less pronounced than in LLD‐dominated areas.

On the plateaus south and west of Echus Chasma, these deposits potentially extend over 50 km inland from the plateau rim, where sparse basal reflections are detected alongside visual evidence of occasional layering and fluvial activity (Figure 1a). South of Echus Chasma, the LLDs appear to transition into WLDs, supported by SHARAD basal reflections and visual evidence of weak layering. The region west of Echus Chasma shows limited SHARAD reflections, likely due to a significant drop in elevation, which causes the SHARAD track to image a steep decline, affecting its capability. In both areas, determining the precise terminus of these units remains challenging due to the limited spatial coverage of HiRISE. Further onto the plateau north of Ius Chasma, the SHARAD reflections associated with these units are contiguous with those of the nonlayered deposits (NDs) discussed in Section 3.2.3.

3.2.3. Nonlayered Deposits (NDs)

We find multiple regions on the VM plateaus that contain concentrations of radar sounding reflections similar to the basal reflections seen in the other units (Figures 1, 2 and 5), both in strength of return, and depth of reflection; however, these regions differ visually from the previously discussed deposits, in that their surface is nonlayered and undifferentiated (Figures 3c and 3f). It is noteworthy that NDs are not found in areas with low or sloped topography and the largest deposit is found on a topographic high on the plateau north of Ius Chasma (Figure 1b). At CTX and MOC resolution, NDs appear mostly smooth or featureless and are devoid of the clear tonal variations and contrast visible in the LLDs or WLDs (Figure 5c). The available HiRISE imagery within these deposits reveals sections of the ND do contain expansive regions with superficial bright deltoids, bearded craters, and TAR‐like structures (Figures 3f–3i), suggesting a connection between these three different deposits, and these surface bedforms. Despite this, these deposits generally appear unremarkable in visual imagery compared to LLDs and WLDs. Our mapping of the NDs are characterized exclusively by the concentration of SHARAD reflections found within them and would otherwise have been unidentifiable.

Fluvio‐lacustrine features seen and discussed with the other rim deposits are not present in NDs. It is notable that while the LLDs and WLDs often surround or enclose sections of the chasmata rim that are dominated by tributary amphitheater‐headed canyons, the NDs tend to be in areas that contain little to none of these secondary canyon systems.

Figure 5 displays a basal reflection that transects the three different rim deposits identified. The basal reflection within this SHARAD track appears to be sustained throughout its length, only disconnecting due to grabens. There is no observable transition between units. Figures 5c–5e demonstrate the differences in surface morphology between the three distinct rim deposits.

4. Discussion

4.1. Geologic Setting and Unit History

This new mapping of western VM is more extensive than previous efforts as we include sounding radar and updated visible imagery coverage. Because of this increased coverage and inclusion of subsurface interfaces, two new units (WLDs and NDs) were identified that are contiguous with the previously mapped LLDs. Radar evidence shows no significant difference between basal reflections in these regions (Figure 5); however, surface expressions in the regions are quite distinct.

The lack of radar detections beyond 100 km away from the chasmata rims is a clue that proximity to the canyon was important for the preservation of the rim deposits. Additionally, the units tend to thin as they extend farther from the chasmata rim, seen in Figures 2a and 2c. We investigated the entire region for subsurface reflections and found none outside of the detections shown in Figure 1. One possible alternative explanation may include interference from clutter caused by surface textures; however, clutter would only raise questions about possible detections (false positives), not necessarily obscure them entirely (false negatives). Another alternative is that any units would be too small to observe with SHARAD's footprint (smaller than 5 × 5 km). Disconnected units with that small of an area would support our interpretation of preservation only near the rim.

LLDs and WLDs tend to surround tributary amphitheater‐headed canyon systems. The formation process of these canyon heads is still a matter of debate as they have been attributed to groundwater seepage erosion, crater lake overflow (Marra et al., 2014), fluvial transport erosion (Mangold et al., 2008), mega‐flooding (Lamb et al., 2014), or some combination of these systems. Although not completely understood, it is generally agreed that water‐rich environments played a role in their formation. The concentration of LLDs and WLDs, posited here to be sedimentary in origin, in their vicinity hints that water likely played a key role in the unit differentiation and preservation near to the rims of the canyons. This is supported by past work that found evidence for aqueously altered materials at these locations (Le Deit et al., 2010; Weitz et al., 2008, 2010). Sections of the canyon rim that lack tributary canyons generally do not contain any LLDs or WLDs.

We interpret the contrasting observations, including morphological differences not detectable by radar and the contiguous nature of the deposits, to suggest that the three rim deposit types share a common origin, but reflect a spectrum of geomorphic modification. They appear to have experienced varying degrees of sedimentation, cementation/lithification, erosion, and potentially alteration, within different types of aqueous environments, resulting in their present state. We propose that this is due to the geographic setting and surrounding environmental conditions, namely the proximity to precipitation in the form of rain or snow, and fluvio‐lacustrine systems that would rework material and form layered sediments at the LLDs and WLDs but not the NDs. The positioning of the altered deposits (LLDs, WLDs) near the canyon rim places them in areas where precipitation could accumulate. Their occurrence on downslopes or in topographic lows (Figure 1b) suggests they were in environments favorable for both surface runoff and standing water.

LLDs are most likely to have experienced lacustrine environments and aqueous alteration. This is supported by the spectroscopically detected hydrated minerals located within the LLD (Le Deit et al., 2010; Weitz et al., 2008, 2010). A plausible scenario involves repeated pyroclastic deposits being emplaced in a lacustrine setting, where the interaction between volcanic ashfall and standing water contributed to the formation of finely layered sediments. Over time, alternating cycles of sediment deposition and water interaction, potentially driven by episodic flooding or evaporation, could have promoted the formation of distinct mineral layers, with pyroclastic materials interbedded with evaporites. This combination of lacustrine sedimentation and volcanic activity would create a complex stratigraphy, which, when later subjected to erosion or diagenesis, might further modify the LLDs, leading to the layered structures observed today. WLDs likely experienced shorter and/or less significant wet periods, possibly involving only intermittent fluvial rather than lacustrine settings. This limited exposure would not allow for sufficient alteration to be detected spectroscopically. Alternatively, WLDs may be sufficiently mantled in dust to prohibit their detection. NDs, with no geomorphic or spectral evidence of aqueous encounters, may have experienced little exposure to water. Figure 6 shows a simplified model of this proposed scenario.

Figure 6.

Figure 6

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Illustration of the rim deposits shown around Ius Chasma. Units are shown to abut one another and have different levels of stratification. Cause of stratification is likely related to the amount of water available during the sedimentary processes that occurred in each region. Initial deposition of material arises from Tharsis and potentially Noctis Mons related volcanism and pyroclastic airfall.

4.2. Source of Rim Deposit Material

Previous investigations into LLDs suggest a pyroclastic origin for the initial material accumulation and date it to the Late Hesperian (Le Deit et al., 2010; Weitz et al., 2008, 2010). Studies modeling the distribution of ash fall from Ascraeus, Pavonis and Arsia Montes (∼2,000 km west of the region examined in this study) show that they could contribute significant pyroclastic material to the plains surrounding western VM (Hynek et al., 2003; Kerber et al., 2011, 2012). Based on modeled ash dispersal patterns, Kerber et al. (2012) illustrate that the rim deposits being emplaced through pyroclastic volcanism is a viable hypothesis, and the most likely source of deposit material. Modeling indicates that ashfall contributions to the regions where we have mapped rim deposits exceed a total thickness of 200 m, which is far thicker than observed; however, these models are contingent upon several assumptions, including the volume of ash expelled, the frequency and magnitude of eruptions, and the duration over which these events occurred. Additionally, the models do not account for erosional processes within deposition events or afterward, which could have significantly altered the deposit thickness. Lastly, the modeling indicates that the VM plateaus in question lie near the maximum extent of the ash dispersal patterns. As such, while these patterns offer valuable insights, the total volume and distribution of the deposits are likely affected by factors not fully accounted for in the model.

While the previously discussed volcanoes could plausibly account for material deposition, a source closer to the region of interest would strengthen the hypothesis of a pyroclastic origin for the rim deposits. Recent research has proposed the existence of a volcanic edifice (provisionally labeled “Noctis Mons”) situated within Noctis Labyrinthus (Figure 7) (Lee & Shubham, 2024). This putative volcano is at the correct latitude (exactly due west of the Ius Chasma) and is less than 500 km away from the nearest identified rim deposits, placing it over 1,100 km closer than the large volcanoes modeled by Kerber et al. (2012). Based on the inferred profile of Noctis Mons (Figure 7c), the caldera was ∼30 km in diameter prior to collapse, and the caldera depth, along with its prominence above the surrounding terrain is ∼3 km. This places Noctis Mons in a similar structural category as the various shield volcanoes found in the Tharsis region, namely Tharsis Tholus, Biblis Tholus, and Ulysses Tholus. Shield volcanos are formed mainly through effusive eruptions rather than explosive pyroclastic volcanism (Baratoux et al., 2009), such as those modeled by Kerber et al. (2012). However, due to the extremely degraded nature of the entire structure of Noctis Mons, it is difficult to determine conclusively if explosive eruptions were absent in its creation. Evidence of pyroclastic deposition in the region has been identified and attributed to Noctis Mons suggesting explosive events were present in its history (Lee & Shubham, 2024). It is plausible that the collapse and creation of Noctis Labyrinthus exacerbated volcanic activity and may have led to pyroclastic eruptions that contributed to the plateau rim deposits in VM. The collapse and subsequent formation of Noctis Labyrinthus have been dated to the Late Hesperian (Thollot et al., 2012), suggesting that the timeline for accumulation of rim deposit material is reasonable. While detailed modeling using global circulation models focused on Noctis Mons are beyond the scope of this study, the relative proximity of Noctis Mons to the rim deposits in VM suggests that regions of interest likely fall within an area of near‐maximal pyroclastic dispersal.

Figure 7.

Figure 7

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(a) CTX Mosaic image of the Noctis Mons caldera. Concentric terraced collapse features are visible, typical of caldera collapse. (b) Colorized MOLA elevation (red = high, yellow = low) of large‐scale region centered on the Noctis Mons caldera, white circle indicates structure extent, colored lines denote profiles plotted in panel (c). (c) Radial profile lines of volcanic edifice, with inferred profile prior to degradation displayed by thick white outline.

The discovery of two additional contiguous rim deposits (namely the WLDs and NDs) that likely share the same origin and extend over a much larger surface area than the LLDs alone bolsters the ashfall hypothesis. While the LLDs contribute less than two‐thirds of all confirmed rim deposits, and account for less than half of all potential deposits (Table 1), the presence of these additional deposits supports the notion of a more extensive depositional event or events. A broader distribution of material from the proposed volcanic sources removes the necessity to explain the selective and discontinuous deposition of material when considering the LLDs in isolation.

Table 1.

Surface Area Coverage of Rim Deposits

Light‐toned layered deposits Weakly layered deposits Nonlayered deposits All rim deposits
Validated unit area (km2) 44079.12 15623.1 8072.7 67,774.9
Potential expanded unit area (km2) N/A 23236.4 2334.6 25,571.1
Total area (km2) 44079.12 39859.5 10407.3 94,345.9
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This raises the question of why these rim deposits are not even more widespread than observed. While the original distribution of ashfall may have been more widespread, blanketing the entire region, induration likely only occurred under specific conditions, such as in basins, in areas with sufficient water, or in areas with less aeolian forces acting on the landscape. These conditions protected the materials over the >2 Ga of aeolian erosion, leading to the rim deposits we see today. There is a general eastward downslope gradient extending away from Noctis Mons, in addition to canyon facing downhill gradients. This is especially apparent on the plateau south of Ius Chasma. This topography could have favored transportation and induration of material in its current location. Additionally, it is possible that the NDs may be more extensive than currently observed but remain undetected due to the limitations of SHARAD's capabilities, including vertical resolution.

4.3. Potential Sources of Aqueous Environments

The scenarios discussed in this section illustrate that past water presence in this region is supported by the scientific community. However, while these scenarios or others could have supplied water and created aqueous environments, further testing of these hypotheses is needed. While we do not attempt to identify the source of water required to chemically and physically alter the initial pyroclastic deposits, we provide some potential scenarios that are plausible based on previous literature.

Transient paleolakes within the VM chasmata (Kite et al., 2011; Quantin et al., 2005) could have provided lake‐induced precipitation over the canyon rims. Paleolakes have the benefit of explaining relevant observations such as the proximity to and distribution of LLDs and WLDs near chasmata rims. In one scenario, water vapor arising from paleolakes within the chasmata themselves would disperse outward from its source, then cool and precipitate through lake‐effect storms (Kite et al., 2011). Deposits with close proximity to the rim edge would interact with this precipitation and experience diagenesis. Deposits farther inland would not receive this precipitation, and not be preserved.

Kakaria and Yin (2023) proposed that late Hesperian glacial processes played a significant role in shaping the pit chains, dendritic gullies, sinuous troughs, hummocky terrain, and surficial boulders observed in the western VM. According to their hypothesis, subglacial water channels inundated vast areas across the VM plateaus, including regions where LLDs are present. This influx of water led to the development of landforms such as inverted channels and pit chains. The presence of water would have created an aqueous environment conducive to the reworking of the rim deposits. Although Kakaria and Yin's (2023) study did not specifically focus on LLDs, their hypothesis supports the broader possibility of water activity in this region within the appropriate timeframe, suggesting a plausible scenario in which these deposits could have been modified. Remnant ice may even be present today in this region (Gourronc et al., 2014; Lee & Shubham, 2024).

Volcanic activity could provide another potential source of water for the plateaus in the form of ice and snow. Modeling of explosive eruptions from Apollinaris Mons and Syrtis Major suggests that the released water vapor may have precipitated as ice and ash aggregates, potentially reaching the western VM plateaus (Hamid, Clarke, & Kerber, 2024). Models of passive degassing from other volcanoes in Tharsis demonstrated the release of significant amounts of water vapor, which accumulated locally around the volcano centers as ice (Hamid, Kerber, et al., 2024). Although ice accumulation around these distant volcanic centers would be too far to affect western VM, the Noctis Mons construct is located just a few hundred kilometers from the rim deposits. If Noctis Mons was more prone to passive degassing events rather than explosive volcanism, it would present a compelling candidate for contributing water vapor and ice to the western VM plateaus. Over time, cycles of sublimation and deposition may have contributed to the formation of the observed layered terrains through gradual accumulation, modification, and erosion.

5. Conclusions

In combination with visible imagery, we expanded on the mapped extents of the inferred sedimentary deposits using data from extensive SHARAD coverage of VM. We used SHARAD data to map basal reflections in western VM and extended them outside of the previously known bounds of the LLDs. Reflections associated with the extended units are indistinguishable from reflections within their boundaries. Mapping led to the discovery and classification of two new units: the WLDs and NDs that have decreasingly layered morphology. These three rim deposits appear to be contiguous and grade from one into another. Radar analysis does not distinguish between these units. We propose that the three units were laid down initially from the same source. LLDs and WLDs then experienced aqueous periods that instigated sedimentation and alteration processes. These processes were absent in the NDs due to a lack of aqueous periods. Following others, we hypothesize that atmospheric deposition of pyroclastic material from volcanic eruptions proximal to the region deposited the material. This volcanic ash was then reworked into LLDs and WLDs by fluvial and lacustrine activity, mobilizing the sediment into topographic lows, where they stratified. Little or no alteration occurred at the NDs. Eventually, all units lithified and were preserved.

In the discussion, we explored the origin of the volcanic ash contributing to the rim deposits, with the Tharsis volcanoes identified as plausible sources. Recently, another potential source has emerged: a severely degraded volcanic structure informally labeled Noctis Mons. Situated within the Noctis Labyrinthus region, this putative shield volcano lies close enough to western VM to supply pyroclastic ashfall while also acting as one potential source of water vapor through passive degassing or precipitation through explosive eruptions. Lastly, we considered and discussed other potential sources of water in the area, such as ancient glacial processes, or precipitation driven by paleolake‐induced storms.

Acknowledgments

The authors gratefully acknowledge the financial support of a NASA MDAP Grant (80NSS‐C17K0437), a Natural Sciences and Engineering Research Council of Canada Discovery Grant (RGPIN‐2019‐06351), and a Canadian Space Agency Research Opportunities in Space Science Grant (22EXPROSS3) to I.B. Smith. Thanks to SeisWare for the radar interpretation academic license. We are grateful to the SHARAD, HiRISE, CTX, MOC, and THEMIS teams for collection of the data used in this study and the Murray Lab for their global CTX mosaic. We would like to thank our reviewers for their insightful comments and suggestions, which improved the quality of this work.

Mishev, I. G. , Smith, I. B. , Quantin, C. , Thollot, P. , Putzig, N. E. , Viviano, C. , et al. (2024). Mapping of western Valles marineris light‐toned layered deposits and newly classified rim deposits. Journal of Geophysical Research: Planets, 129, e2024JE008425. 10.1029/2024JE008425

Data Availability Statement

Data used in the SHARAD, HiRISE, and MOC figures can be found in the tables provided in the referenced Zenodo repositories (Mishev, 2024a, 2024b), and in the Planetary Data System here: https://pds‐geosciences.wustl.edu/missions/mro/sharad.htm, https://www.uahirise.org/catalog/, https://pds‐geosciences.wustl.edu/missions/mgs/moc.html.

References

  1. Baratoux, D. , Pinet, P. , Toplis, M. J. , Mangold, N. , Greeley, R. , & Baptista, A. R. (2009). Shape, rheology and emplacement times of small Martian shield volcanoes. Journal of Volcanology and Geothermal Research, 185(1), 47–68. 10.1016/j.jvolgeores.2009.05.003 [DOI] [Google Scholar]
  2. Bell, I. J. F. , Malin, M. C. , Caplinger, M. A. , Fahle, J. , Wolff, M. J. , Cantor, B. A. , et al. (2013). Calibration and performance of the Mars reconnaissance orbiter context camera (CTX). International Journal of Mars Science and Exploration, 8, 1–14. 10.1555/mars.2013.0001 [DOI] [Google Scholar]
  3. Bishop, J. L. , Parente, M. , Weitz, C. M. , Noe Dobrea, E. Z. , Roach, L. H. , Murchie, S. L. , et al. (2009). Mineralogy of Juventae chasma: Sulfates in the light‐toned mounds, mafic minerals in the bedrock, and hydrated silica and hydroxylated ferric sulfate on the plateau. Journal of Geophysical Research, 114(E2). 10.1029/2009JE003352 [DOI] [Google Scholar]
  4. Campbell, M. J. , & Ulrichs, J. (1969). Electrical properties of rocks and their significance for lunar radar observations. Journal of Geophysical Research (1896‐1977), 74(25), 5867–5881. 10.1029/JB074i025p05867 [DOI] [Google Scholar]
  5. Choudhary, P. , Holt, J. W. , & Kempf, S. D. (2016). Surface clutter and echo location analysis for the interpretation of SHARAD data from Mars. IEEE Geoscience and Remote Sensing Letters, 13(9), 1285–1289. 10.1109/lgrs.2016.2581799 [DOI] [Google Scholar]
  6. Christensen, P. R. , Engle, E. , Anwar, S. , Dickenshied, S. , Noss, D. , Gorelick, N. , & Weiss‐Malik, M. (2009). JMARS ‐ A planetary GIS. 2009, IN22A‐06. AGU Fall Meeting Abstracts. [Google Scholar]
  7. Christensen, P. R. , Jakosky, B. M. , Kieffer, H. H. , Malin, M. C. , McSween, H. Y., Jr. , Nealson, K. , et al. (2004). The Thermal Emission Imaging System (THEMIS) for the Mars 2001 Odyssey mission. Space Science Reviews, 110(1/2), 85–130. 10.1023/B:SPAC.0000021008.16305.94 [DOI] [Google Scholar]
  8. Christoffersen, M. S. , Holt, J. W. , Kempf, S. D. , & O’Connell, J. D. (2021). MRO SHARAD clutter simulations bundle (No. urn:nasa:pds:mro_sharad_simulations::1.0; Issue urn:nasa:pds:mro_sharad_simulations::1.0) [Dataset]. 10.17189/nbdh-2k53 [DOI]
  9. Dickson, J. L. , Ehlmann, B. L. , Kerber, L. , & Fassett, C. I. (2024). The global context camera (CTX) mosaic of Mars: A product of information‐preserving image data processing. Earth and Space Science, 11(7), e2024EA003555. 10.1029/2024EA003555 [DOI] [Google Scholar]
  10. Geissler, P. E. (2014). The birth and death of transverse Aeolian ridges on Mars. Journal of Geophysical Research: Planets, 119(12), 2583–2599. 10.1002/2014JE004633 [DOI] [Google Scholar]
  11. Gourronc, M. , Bourgeois, O. , Mège, D. , Pochat, S. , Bultel, B. , Massé, M. , et al. (2014). One million cubic kilometers of fossil ice in Valles Marineris: Relicts of a 3.5Gy old glacial landsystem along the Martian equator. Geomorphology, 204, 235–255. 10.1016/j.geomorph.2013.08.009 [DOI] [Google Scholar]
  12. Hamid, S. S. , Clarke, A. B. , & Kerber, L. (2024). Precipitation induced by explosive volcanism on early Mars and its implications for ice in unusual equatorial regions. Tenth International Conference on Mars, 3007, 3416. https://www.hou.usra.edu/meetings/tenthmars2024/pdf/3416.pdf [Google Scholar]
  13. Hamid, S. S. , Kerber, L. , Clarke, A. B. , & Forget, F. (2024). The delivery of water ice to the Martian surface by passive degassing. Icarus, 416, 116084. 10.1016/j.icarus.2024.116084 [DOI] [Google Scholar]
  14. Hynek, B. M. , Phillips, R. J. , & Arvidson, R. E. (2003). Explosive volcanism in the tharsis region: Global evidence in the Martian geologic record. Journal of Geophysical Research, 108(E9). 10.1029/2003JE002062 [DOI] [Google Scholar]
  15. Kakaria, R. , & Yin, A. (2023). Subglacial catastrophic‐flood origin of linear and curvilinear flat‐rimmed pit chains on Mars: Evidence from geomorphological mapping and detailed landsystem analysis. Icarus, 395, 115439. 10.1016/j.icarus.2023.115439 [DOI] [Google Scholar]
  16. Kerber, L. , Head, J. W. , Madeleine, J.‐B. , Forget, F. , & Wilson, L. (2011). The dispersal of pyroclasts from Apollinaris patera, Mars: Implications for the origin of the medusae fossae formation. Icarus, 216(1), 212–220. 10.1016/j.icarus.2011.07.035 [DOI] [Google Scholar]
  17. Kerber, L. , Head, J. W. , Madeleine, J.‐B. , Forget, F. , & Wilson, L. (2012). The dispersal of pyroclasts from ancient explosive volcanoes on Mars: Implications for the friable layered deposits. Icarus, 219(1), 358–381. 10.1016/j.icarus.2012.03.016 [DOI] [Google Scholar]
  18. Kite, E. S. , Rafkin, S. , Michaels, T. I. , Dietrich, W. E. , & Manga, M. (2011). Chaos terrain, storms, and past climate on Mars. Journal of Geophysical Research, 116(E10), E10002. 10.1029/2010JE003792 [DOI] [Google Scholar]
  19. Kochel, R. C. , & Piper, J. F. (1986). Morphology of large valleys on Hawaii: Evidence for groundwater sapping and comparisons with Martian valleys. Journal of Geophysical Research, 91(B13). 10.1029/JB091iB13p0E175 [DOI] [Google Scholar]
  20. Lamb, M. P. , Mackey, B. H. , & Farley, K. A. (2014). Amphitheater‐headed canyons formed by megaflooding at Malad Gorge, Idaho. Proceedings of the National Academy of Sciences (Vol. 111(1), 57–62). 10.1073/pnas.1312251111 [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Le Deit, L. , Bourgeois, O. , Mège, D. , Hauber, E. , Le Mouélic, S. , Massé, M. , et al. (2010). Morphology, stratigraphy, and mineralogical composition of a layered formation covering the plateaus around Valles Marineris, Mars: Implications for its geological history. Icarus, 208(2), 684–703. 10.1016/j.icarus.2010.03.012 [DOI] [Google Scholar]
  22. Le Deit, L. , Flahaut, J. , Quantin, C. , Hauber, E. , Mège, D. , Bourgeois, O. , et al. (2012). Extensive surface pedogenic alteration of the Martian Noachian crust suggested by plateau phyllosilicates around Valles Marineris. Journal of Geophysical Research, 117(E11). 10.1029/2011JE003983 [DOI] [Google Scholar]
  23. Lee, P. , & Shubham, S. (2024). Large eroded volcano complex and buried glacier ice in eastern Noctis Labyrinthus: Evidence for recent volcanism and glaciation near Mars’ equator. 55th Lunar and Planetary Science Conference, 3040, 2745. [Google Scholar]
  24. Malin, M. C. , Bell, J. F. , Cantor, B. A. , Caplinger, M. A. , Calvin, W. M. , Clancy, R. T. , et al. (2007). Context camera investigation on board the Mars reconnaissance orbiter. Journal of Geophysical Research, 112(E5). 10.1029/2006JE002808 [DOI] [Google Scholar]
  25. Malin, M. C. , Danielson, G. E. , Ingersoll, A. P. , Masursky, H. , Veverka, J. , Ravine, M. A. , & Soulanille, T. A. (1992). Mars observer camera. Journal of Geophysical Research, 97(E5), 7699–7718. 10.1029/92JE00340 [DOI] [Google Scholar]
  26. Malin, M. C. , & Edgett, K. S. (2001). Mars global surveyor Mars orbiter camera: Interplanetary cruise through primary mission. Journal of Geophysical Research, 106(E10), 23429–23570. 10.1029/2000JE001455 [DOI] [Google Scholar]
  27. Mangold, N. , Ansan, V. , Masson, P. H. , Quantin, C. , & Neukum, G. (2008). Geomorphic study of fluvial landforms on the northern Valles Marineris plateau, Mars. Journal of Geophysical Research, 113(E8). 10.1029/2007JE002985 [DOI] [Google Scholar]
  28. Mangold, N. , Quantin, C. , Ansan, V. , Delacourt, C. , & Allemand, P. (2004). Evidence for precipitation on Mars from dendritic valleys in the Valles Marineris area. Science, 305(5680), 78–81. 10.1126/science.1097549 [DOI] [PubMed] [Google Scholar]
  29. Marra, W. A. , Braat, L. , Baar, A. W. , & Kleinhans, M. G. (2014). Valley formation by groundwater seepage, pressurized groundwater outbursts and crater‐lake overflow in flume experiments with implications for Mars. Icarus, 232, 97–117. 10.1016/j.icarus.2013.12.026 [DOI] [Google Scholar]
  30. McCauley, J. F. (1978). Geologic map of the coprates quadrangle of Mars (report No. 897; IMAP, issue 897). USGS Publications Warehouse. 10.3133/i897 [DOI] [Google Scholar]
  31. McEwen, A. S. , Eliason, E. M. , Bergstrom, J. W. , Bridges, N. T. , Hansen, C. J. , Delamere, W. A. , et al. (2007). Mars reconnaissance orbiter’s High Resolution Imaging Science Experiment (HiRISE). Journal of Geophysical Research: Planets (1991–2012), 112(E5). 10.1029/2005je002605 [DOI] [Google Scholar]
  32. Milliken, R. E. , Swayze, G. A. , Arvidson, R. E. , Bishop, J. L. , Clark, R. N. , Ehlmann, B. L. , et al. (2008). Opaline silica in young deposits on Mars. Geology, 36(11), 847. 10.1130/G24967A.1 [DOI] [Google Scholar]
  33. Mishev, I. (2024a). HiRISE and MOC‐NA images used in mapping of western Valles Marineris light‐toned layered deposits and newly classified rim deposits [Dataset]. Zenodo. 10.5281/zenodo.14193855 [DOI]
  34. Mishev, I. (2024b). SHARAD tracks mapped in mapping of western Valles Marineris light‐toned layered deposits and newly classified rim deposits [Dataset]. Zenodo. 10.5281/zenodo.14193915 [DOI]
  35. Murchie, S. , Arvidson, R. , Bedini, P. , Beisser, K. , Bibring, J.‐P. , Bishop, J. , et al. (2007). Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on Mars Reconnaissance Orbiter (MRO). Journal of Geophysical Research, 112(E5). 10.1029/2006JE002682 [DOI] [Google Scholar]
  36. Nunes, D. C. , & Phillips, R. J. (2006). Radar subsurface mapping of the polar layered deposits on Mars. Journal of Geophysical Research, 111(E6). 10.1029/2005je002609 [DOI] [Google Scholar]
  37. Putzig, N. E. , Seu, R. , Morgan, G. A. , Smith, I. B. , Campbell, B. A. , Perry, M. R. , & Mastrogiuseppe, M. (2024). Science results from sixteen years of MRO SHARAD operations. Icarus, 419, 115715. 10.1016/j.icarus.2023.115715 [DOI] [Google Scholar]
  38. Quantin, C. , Allemand, P. , Mangold, N. , Dromart, G. , & Delacourt, C. (2005). Fluvial and lacustrine activity on layered deposits in Melas Chasma, Valles Marineris, Mars. Journal of Geophysical Research, 110(E12). 10.1029/2005JE002440 [DOI] [Google Scholar]
  39. Runyon, K. D. , Viviano, C. E. , & Day, M. (2021). Abraded pyroclastic linear paleodunes in Syria and daedalia Plana, Mars. Earth and Planetary Science Letters, 557, 116719. 10.1016/j.epsl.2020.116719 [DOI] [Google Scholar]
  40. Scott, D. H. , & Tanaka, K. L. (1986). Geologic map of the western equatorial region of Mars (Vol. 1). Citeseer. [Google Scholar]
  41. Seu, R. , Biccari, D. , Orosei, R. , Lorenzoni, L. V. , Phillips, R. J. , Marinangeli, L. , et al. (2004). Sharad: The MRO 2005 shallow radar. Planetary and Space Science, 52(1), 157–166. 10.1016/j.pss.2003.08.024 [DOI] [Google Scholar]
  42. Seu, R. , Phillips, R. J. , Biccari, D. , Orosei, R. , Masdea, A. , Picardi, G. , et al. (2007). SHARAD sounding radar on the Mars Reconnaissance Orbiter. Journal of Geophysical Research: Planets, 112(E5), E05S05. 10.1029/2006je002745 [DOI] [Google Scholar]
  43. Smith, D. E. , Zuber, M. T. , Frey, H. V. , Garvin, J. B. , Head, J. W. , Muhleman, D. O. , et al. (2001). Mars orbiter laser altimeter: Experiment summary after the first year of global mapping of Mars. Journal of Geophysical Research, 106(E10), 23689–23722. 10.1029/2000je001364 [DOI] [Google Scholar]
  44. Thollot, P. , Mangold, N. , Ansan, V. , Le Mouélic, S. , Milliken, R. E. , Bishop, J. L. , et al. (2012). Most Mars minerals in a nutshell: Various alteration phases formed in a single environment in Noctis Labyrinthus. Journal of Geophysical Research, 117(E11). 10.1029/2011JE004028 [DOI] [Google Scholar]
  45. Ulaby, F. , Bengal, T. , East, J. , Dobson, M. , Garvin, J. , & Evans, D. (1988). Microwave dielectric spectrum of rocks. Retrieved from https://ntrs.nasa.gov/api/citations/19880010447/downloads/19880010447.pdf
  46. Weitz, C. M. , Milliken, R. E. , Grant, J. A. , McEwen, A. S. , Williams, R. M. E. , & Bishop, J. L. (2008). Light‐toned strata and inverted channels adjacent to Juventae and Ganges chasmata, Mars. Geophysical Research Letters, 35(19). 10.1029/2008GL035317 [DOI] [Google Scholar]
  47. Weitz, C. M. , Milliken, R. E. , Grant, J. A. , McEwen, A. S. , Williams, R. M. E. , Bishop, J. L. , & Thomson, B. J. (2010). Mars Reconnaissance Orbiter observations of light‐toned layered deposits and associated fluvial landforms on the plateaus adjacent to Valles Marineris. Icarus, 205(1), 73–102. 10.1016/j.icarus.2009.04.017 [DOI] [Google Scholar]
  48. Whitbeck, N. , Tanaka, K. , & Scott, D. (1991). Geologic map of the Valles Marineris region. Mars, United States Geological Survey Miscellaneous Investigations Series, Map I‐2010, Scale, 1(2,000,000). [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Data Citations

  1. Christoffersen, M. S. , Holt, J. W. , Kempf, S. D. , & O’Connell, J. D. (2021). MRO SHARAD clutter simulations bundle (No. urn:nasa:pds:mro_sharad_simulations::1.0; Issue urn:nasa:pds:mro_sharad_simulations::1.0) [Dataset]. 10.17189/nbdh-2k53 [DOI]
  2. Mishev, I. (2024a). HiRISE and MOC‐NA images used in mapping of western Valles Marineris light‐toned layered deposits and newly classified rim deposits [Dataset]. Zenodo. 10.5281/zenodo.14193855 [DOI]
  3. Mishev, I. (2024b). SHARAD tracks mapped in mapping of western Valles Marineris light‐toned layered deposits and newly classified rim deposits [Dataset]. Zenodo. 10.5281/zenodo.14193915 [DOI]

Data Availability Statement

Data used in the SHARAD, HiRISE, and MOC figures can be found in the tables provided in the referenced Zenodo repositories (Mishev, 2024a, 2024b), and in the Planetary Data System here: https://pds‐geosciences.wustl.edu/missions/mro/sharad.htm, https://www.uahirise.org/catalog/, https://pds‐geosciences.wustl.edu/missions/mgs/moc.html.

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