Christopher M. Fedo

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Verified

Christopher verified their affiliation via an institutional email.

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• PhD
• Professor (Full) at University of Tennessee at Knoxville

The Mars Science Laboratory rover, Curiosity, has been examining strata from a period of Martian history where extensive clay mineral formation transitioned to sulfate mineral formation. This mineralogic change corresponds to a change from a wetter to a more arid climate. Among the tools used by Curiosity to study the rocks that recorded this trans...

The Amapari Marker Band (AMB) is a layer within the Mount Sharp stratigraphy that has been mapped around the Gale crater in orbital images and was recently investigated up close by the Curiosity rover. Symmetric wave ripple marks within the AMB indicate a lacustrine depositional environment in the area investigated along the Curiosity traverse. The...

Symmetrical wave ripples identified with NASA’s Curiosity rover in ancient lake deposits at Gale crater provide a key paleoclimate constraint for early Mars: At the time of ripple formation, climate conditions must have supported ice-free liquid water on the surface of Mars. These features are the most definitive examples of wave ripples on another...

Introduction: Sedimentary rocks on Mars preserve a record of past depositional and diagenetic conditions that offers an opportunity to investigate the planet's geologic and climate history beyond the limits of the geomorphic and impact crater records. Since 2019, new rover and orbiter observations and analyses of the Martian sedimentary record, alo...

This study uses data from the Mars Science Laboratory Curiosity rover to document the facies of the Sutton Island member of the Murray formation, interpret paleoenvironments, and establish key stratigraphic transitions at Gale crater. Two facies associations were identified: Facies Association 1 (FA1) and Facies Association 2 (FA2). Individual faci...

The early environmental history of Mars is encoded in the planet's record of sedimentary rocks. Since 2012, the Curiosity rover has been ascending Mount Sharp, Gale crater's central mound, making detailed observations of sedimentary strata exposed there. The primary depositional setting represented by the rocks examined thus far has been a perennia...

The Mars Science Laboratory (MSL) Curiosity rover continues to ascend the foothills of Aeolis Mons (Mt. Sharp), Gale crater, Mars, with the goal of characterizing former habitable environ-ments [1]. Previously, Curiosity encountered evidence for fluvial and lacustrine environments [2], which ex-isted prior to the formation and exhumation of Aeolis...

The stratigraphy preserved within Aeolis Mons in Gale crater (Mars) shows a major transition from a phyllosilicate-bearing unit, which in situ data show is composed of mudstone-rich strata (with subordinate sandstones) recording deposition in lacustrine to fluvial settings into a major sulfatebearing unit that is hundreds of meters thick (the Layer...

Alluvial fans formed on Mars during the late Hesperian to early Amazonian in a climatic transition from a time of regular surface water activity to the current dry and cold climate. The depositional environments recorded by alluvial fans represent the final era of potential habitability on the Martian surface. Alluvial fan deposits can often look s...

The Mars Science Laboratory rover, Curiosity, explored the clay mineral‐bearing Glen Torridon region for 1 Martian year between January 2019 and January 2021, including a short campaign onto the Greenheugh pediment. The Glen Torridon campaign sought to characterize the geology of the area, seek evidence of habitable environments, and document the o...

The Glen Torridon (GT) region in Gale crater, Mars is a region with strong clay mineral signatures inferred from orbital spectroscopy. The CheMin X‐ray diffraction (XRD) instrument onboard the Mars Science Laboratory rover, Curiosity, measured some of the highest clay mineral abundances to date within GT, complementing the orbital detections. GT ma...

Chemical weathering indices (one-dimensional/1D index values) and accompanying ternary plots (two-dimensional/2D compositional space) facilitate quantitative comparison of whole-rock and mineral major-element data, and empirical chemical trends with predicted weathering vectors. However, data analysis in ternary plots is restricted by poles groupin...

The Mars Science Laboratory rover Curiosity encountered nodules rich in manganese and phosphorus while exploring the Knockfarril Hill member of Gale crater on Mars. Deconvolution of X-ray spectroscopy data acquired by the Alpha Particle X-ray Spectrometer (APXS) at the spectral level indicate P2O5 concentrations possibly in excess of 18 wt% and MnO...

Temporal fluctuations of wind strength and direction can influence aeolian bedform morphology and orientation, which can be encoded into the architecture of aeolian deposits. These strata represent a direct record of atmospheric processes and can be used to understand ancient Martian atmospheric processes as well as those on Earth. The strata can:...

Quantitatively determining the amount of chemical weathering within sedimentary rocks (and weathering profiles) took a major step forward with the creation of the chemical index of alteration (CIA) 40 years ago. The CIA relates the proportion of immobile aluminum to the mobile cations of calcium, sodium, and potassium and is grounded in empirical a...

The Glen Torridon (GT) region within Gale crater, Mars, occurs in contact with the southern side of Vera Rubin ridge (VRR), a well‐defined geomorphic feature that is comparatively resistant to erosion. Prior to detailed ground‐based investigation of GT, its geologic relationship with VRR was unknown. Distinct lithologic subunits within the Jura mem...

Between January 2019 and January 2021, the Mars Science Laboratory team explored the Glen Torridon (GT) region in Gale crater (Mars), known for its orbital detection of clay minerals. Mastcam, Mars Hand Lens Imager, and ChemCam data are used in an integrated sedimentological and geochemical study to characterize the Jura member of the upper Murray...

This study utilizes instruments from the Curiosity rover payload to develop an integrated paleoenvironmental and compositional reconstruction for the 65‐m thick interval of stratigraphy comprising the Hartmann's Valley and Karasburg members of the Murray formation, Gale crater, Mars. The stratigraphy consists of cross‐stratified sandstone (Facies 1...

Gale crater, the field site for NASA's Mars Science Laboratory Curiosity rover, contains a diverse and extensive record of aeolian deposition and erosion. This study focuses on a series of regularly spaced, curvilinear, and sometimes branching bedrock ridges that occur within the Glen Torridon region on the lower northwest flank of Aeolis Mons, the...

Wave modeling and analysis of sedimentary structures were used to evaluate whether four examples of symmetrical, reversing, or straight‐crested bedforms in Gale crater sandstones are preserved wave ripples; deposition by waves would demonstrate that the lake was not covered by ice at that time. Wave modeling indicates that regardless of atmospheric...

In situ zircon U-Pb and Hf isotopic data were obtained from ~1.1 Ga intrusive igneous rocks in northern Sonora (MX) and from Grenvillian (0.9 Ga to 1.3 Ga) detrital zircon grains in several Neoproterozoic to Cambrian sandstones from the southern midcontinent of Laurentia. These data were used to refine provenance determinations for the Grenvillian...

Modified clay minerals on Mars Sedimentary rocks exposed in Gale crater on Mars contain extensive clay minerals. Bristow et al. analyzed drill samples collected by the Curiosity rover as it climbed up sedimentary layers in the crater. They found evidence of past reactions with liquid water and sulfate brines, which could have percolated through the...

Rocks that make up the Mesoarchean (~3Ga) Buhwa greenstone belt (BGB) of the Zimbabwe craton divide into three associations: shelf, basinal, and transitional. Chert and iron formation exist within the three associations, allowing the unique opportunity to compare textural and geochemical attributes of iron- and silica-rich rocks from distinct posit...

Lithified aeolian strata encode information about ancient planetary surface processes and the climate during deposition. Decoding these strata provides insight regarding past sediment transport processes, bedform kinematics, depositional landscape, and the prevailing climate. Deciphering these signatures requires a detailed analysis of sedimentary...

Since Jan. 2019 (~sol 2300), the Mars Science Laboratory rover Curiosity has been ex-ploring the Glen Torridon (GT) region of Gale Crater, seeking to examine clay-bearing strata initially detected using orbiter data [1]. The presence of hydrated clay minerals has major implications for understanding the wet early Mars. The sedimentary record of the...

This paper provides an overview of the Curiosity rover's exploration at Vera Rubin ridge (VRR) and summarizes the science results. VRR is a distinct geomorphic feature on lower Aeolis Mons (informally known as Mount Sharp) that was identified in orbital data based on its distinct texture, topographic expression, and association with a hematite spec...

Curiosity’s southward traverse up the lower north slope of Mt. Sharp (in Gale crater, Mars) and across Glen Torridon has brought it in contact with the organics-bearing sediments of the Knockfarril Hill member, the light-toned, nodule-rich strata found at Western, Central, and Tower buttes, and to the abrupt truncation of these altered Murray sedim...

Silica-rich Precambrian rocks often preserve geochemical information and microfossil remnants from the early biosphere and could play a critical role in the formation of early crust. Because these rocks are important geochemical and paleontological archives, we need to better constrain their geochemical and isotopic attributes and generate a refine...

Extraformational sediment recycling (old sedimentary rock to new sedimentary rock) is a fundamental aspect of Earth's geological record; tectonism exposes sedimentary rock, whereupon it is weathered and eroded to form new sediment that later becomes lithified. On Mars, tectonism has been minor, but two decades of orbiter instrument-based studies sh...

The Glen Torridon (GT) region in Gale crater, has been explored using the Mars Science Laboratory rover, Curiosity, since January 2019 (~Sol 2300) to document clay-bearing rocks initially detected via orbiter data [1]. The rocks are part of the Murray formation, with lower GT consisting of the Jura member mudstones generally associated with a lacus...

Geochemical results are presented from Curiosity's exploration of Vera Rubin ridge (VRR), in addition to the full chemostratigraphy of the predominantly lacustrine mudstone Murray formation up to and including VRR. VRR is a prominent ridge flanking Aeolis Mons (informally Mt. Sharp), the central mound in Gale crater, Mars, and was a key area of int...

Across the Mojave Desert of southeastern California, outcrops of the Cambrian middle member of the Wood Canyon Formation preserve the deposits of pre-vegetation braided-fluvial and braid-delta environments. One 78-meter-thick section in the southern Marble Mountains, documented here through detailed stratigraphic logging, facies analysis, architect...

The Curiosity rover's exploration of rocks and soils in Gale crater has provided diverse geochemical and mineralogical data sets, underscoring the complex geological history of the region. We report the crystalline, clay mineral, and amorphous phase distributions of four Gale crater rocks from an 80‐m stratigraphic interval. The mineralogy of the f...

Ground‐based bedding orientation measurements are critical to determine the geologic history and processes of sedimentation in Gale crater, Mars. We constrain the dip of lacustrine strata of the Blunts Point, Pettegrove Point, and Jura members of the Murray formation using a combination of regional stratigraphic correlations and bed attitude measur...

For ~500 Martian solar days (sols), the Mars Science Laboratory team explored Vera Rubin ridge (VRR), a topographic feature on the northwest slope of Aeolis Mons. Here we review the sedimentary facies and stratigraphy observed during sols 1,800–2,300, covering more than 100 m of stratigraphic thickness. Curiosity's traverse includes two transects a...

The Glen Torridon (GT) region in Gale crater, Mars, has been explored by the Mars Science Laboratory Curiosity rover since ~Sol 2300 (Feb. '19), seeking traces of the clay-bearing minerals initially detected from orbiter data [1]. The lowermost locations of the GT trough are dominated by the Jura member mudstones, and fine-grained sandstones of the...

Silica-rich Precambrian rocks often preserve geochemical information and microfossil remnants from the early biosphere. Because these rocks are such critical geochemical and paleontological archives, we need robust tools to identify the chemical and physical conditions under which siliceous Precambrian rocks form, and determine how such information...

Lithostratigraphic correlation represents a fundamental tool for interpreting the depositional history and stratal architecture in sedimentary rock successions. On Earth, this is accomplished by measuring the thickness and lithologies through a stratigraphic unit at multiple places along and across strike, then linking similar rock types. Across ki...

The lowermost exposure of the Murray formation in Gale crater, Mars, was interpreted as sediment deposited in an ancient lake based on data collected by the Curiosity rover. Constraining the stratigraphic extent and duration of this environment has important implications for the paleohydrology of Gale. Insights into early Martian environments and p...

The Mars Science Laboratory Curiosity rover arrived at Mars in August 2012 with a primary goal of characterizing the habitability of ancient and modern environments. Curiosity was sent to Gale crater to study a sequence of ∼3.5 Ga old sedimentary rocks that, based on orbital visible and near- to short-wave infrared reflectance spectra, contain seco...

Architectural element analysis and detailed mapping of a 300 m along‐strike exposure of the middle member Wood Canyon Formation, southern Marble Mountains, California, USA, provides new evidence for extensive braided–fluvial channel‐belt deposits with adjacent overbank environments. Three‐dimensional models constructed using ‘Structure from Motion’...

From Sol 750 to 1550, the Curiosity rover documented>100 m thick stack of fine-grained sedimentary rocks making up part of the Murray formation, at the base of Mt Sharp, Gale crater. Here, we use data collected by the ChemCam instrument to estimate the level of chemical weathering in these sedimentary rocks. Both the Chemical Index of Alteration (C...

Inferred grain sizes and possible depositional environments for rocks in the Murray formation, Gale Crater, Mars are presented based on ChemCam LIBS data.

Mars Science Laboratory (MSL) Curiosity rover data are used to describe the morphology of desiccation cracks observed in ancient lacustrine strata at Gale crater, Mars, and to interpret their paleoenvironmental setting. The desiccation cracks indicate subaerial exposure of lacustrine facies in the Sutton Island member of the Murray formation. In as...

We investigated a group of silicified volcanic rocks from the ∼2.72 Ga Hunter Mine Group (HMG), Abitibi Greenstone Belt, Canada, in order to document progressive compositional change associated with alteration in a subaqueous caldera system. Rocks of the HMG divide into three groups based on mineralogy and texture for petrographic and geochemical a...

Rock identification is fundamental to the Curiosity rover investigation in Gale crater, Mars. About 200 m of ancient (3-4 Ga) strata have been explored. The rocks record fluvial-deltaic, lacustrine, and eolian environments. Remote robotic investigation of rocks is challenging; Curiosity carries no rock hammer, makes no thin sections, nor do we ofte...

Multiple sedimentary structures of different scales and representative of various flow conditions were sampled from single, sand-dominated, fluvial channels in the Neoproterozoic (Ediacaran) upper member of the Stirling Quartzite and the Cambrian (Terreneuvian) middle member of the Wood Canyon Formation. Sampling was designed to determine if sortin...

Combined U-Pb ages and Hf isotopic data from 1.0 Ga to 1.3 Ga (Grenvillian) detrital zircon in Neoproterozoic and Cambrian siliciclastic sedimentary rocks in southwest North America, and from igneous zircon in potential Mesoproterozoic source rocks, are used to better assess the provenance of detrital zircon potentially transported across Laurentia...

Combined U-Pb ages and Hf isotopic data of detrital zircon (DZ) grains can be used to improve the spatial resolution of provenance determinations where there are multiple potential source regions. In this study, such data are used to refine the sources of DZs in Neoproterozoic-Cambrian sediment deposited across Laurentia, comprising the so-called “...

Combined U-Pb ages and Hf isotopic data of detrital zircon (DZ) grains can be used to improve the spatial resolution of provenance determinations where there are multiple potential source regions. In this study, such data are used to refine the sources of DZs in Neoproterozoic-Cambrian sediment deposited across Laurentia, comprising the so-called “...

Pillow basalt and chert form integral lithologies comprising many Archean greenstone belt packages. To investigate details of these lithologies in the >3.7 Ga Isua Greenstone Belt, SW Greenland, we measured silicon isotope compositions of quartz crystals, by secondary ion mass spectrometry, from a quartz-cemented, quartz-amygdaloidal basaltic pillo...

The age and origin of the quartz-amphibole-pyroxene (qap) gneiss from the island of Akilia, southern West Greenland, have been the subject of intense debate since the light C-isotope composition of graphite inclusions in apatite was interpreted to indicate the presence of Earth's earliest biological activity. Although this claim for biogenic relict...

Impact shattering of bedrock and wind-driven sorting have been identified as primary processes modifying the size, shape, and roundness of basalt-derived sediments at the Spirit rover landing site in Gusev Crater, Mars. We experimentally explore how physical sorting can cause significant compositional modification of sediment relative to bedrock in...

Introduction: Sedimentary textures provide a rich source of information from which sediment transport and processes can be inferred. Until samples are returned from Mars, textural analysis relies on 2D imagery [1-3]. With images lacking a third dimension, textural image analysis techniques need to be evaluated for their accuracy in representing 3D...

We compared textural parameters from 2-D photos of basaltic sediment with 3-D data to determine inaccuracies in performing 2-D analyses on Mars sediment.

Detrital zircon geochronology coupled with Nd isotopic data constrains the provenance of the Neoproterozoic Johnnie Formation and Stirling Quartzite in the southern Nopah Range, southeastern California, and provides data to test a model of the early tectonic evolution of the southwestern Laurentian continental margin. A total of 228 detrital zircon...

Synthetic sediment produced from the sorting of shattered basalt bedrock demonstrates the possibility for hydrodynamic compositional modification of sediment on Mars and must be considered when interpreting the composition of martian sediment.

Soils in Gusev Crater and Meridiani Planum derive primarily from a surface dominated by basalt. The modal mineralogy of primary (igneous) and secondary (alteration) phases in the soils is estimated using Mössbauer, MiniTES, and APXS spectra. Primary minerals include plagioclase, pyroxene, and olivine with less common apatite, magnetite, and chromit...

A critical factor required to unravel processes that have shaped other planets is a solid understanding of geologic processes as they operate on Earth, and a logical way to understand those processes is to go into the fi eld and view them. We provide a fi eld guide to three locations: (1) Cima volcanic fi eld, south of Baker, California; (2) Rainbo...

In the Death Valley and Mojave Desert regions of southeastern California, the contact separating the lower and middle members of the Wood Canyon Formation (WCF) is currently interpreted as a regional-scale unconformity coincident with the base of the Sauk sequence. Regional mapping of this surface, however, reveals a nonconformable contact with und...

Petrologic and geochemical data confirm that mudstones and sandstones of the Johnnie Formation were the initial siliciclastic deposits laid along the Cordilleran Laurentian margin following the Neoproterozoic break-up of Rodinia. Sedimentary rocks of the Johnnie Formation have corrected CIA values between 63 and 83 (or higher), which suggest modera...