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Photogeologic Map of the Perseverance Rover Field Site in Jezero Crater Constructed by the Mars 2020 Science Team

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Kathryn M. Stack
Kathryn M. Stack
Kathryn M. Stack
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Nathan R. Williams
Nathan R. Williams
Nathan R. Williams
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Fred Calef at California Institute of Technology
Fred Calef
Vivian Z Sun at NASA
Vivian Z Sun
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Abstract and Figures

The Mars 2020 Perseverance rover landing site is located within Jezero crater, a ∼50km\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\sim50~\mbox{km}$\end{document} diameter impact crater interpreted to be a Noachian-aged lake basin inside the western edge of the Isidis impact structure. Jezero hosts remnants of a fluvial delta, inlet and outlet valleys, and infill deposits containing diverse carbonate, mafic, and hydrated minerals. Prior to the launch of the Mars 2020 mission, members of the Science Team collaborated to produce a photogeologic map of the Perseverance landing site in Jezero crater. Mapping was performed at a 1:5000 digital map scale using a 25 cm/pixel High Resolution Imaging Science Experiment (HiRISE) orthoimage mosaic base map and a 1 m/pixel HiRISE stereo digital terrain model. Mapped bedrock and surficial units were distinguished by differences in relative brightness, tone, topography, surface texture, and apparent roughness. Mapped bedrock units are generally consistent with those identified in previously published mapping efforts, but this study’s map includes the distribution of surficial deposits and sub-units of the Jezero delta at a higher level of detail than previous studies. This study considers four possible unit correlations to explain the relative age relationships of major units within the map area. Unit correlations include previously published interpretations as well as those that consider more complex interfingering relationships and alternative relative age relationships. The photogeologic map presented here is the foundation for scientific hypothesis development and strategic planning for Perseverance’s exploration of Jezero crater.
Previous mapping efforts in and around Jezero crater: (a) Inlet valleys, outlet valley, and western and northern fan deposits, modified from Fig. 1b in Fassett and Head (2005), (b) modified from Fig. 1c in Ehlmann et al. (2008); yellow is Northern delta, orange is Western delta, blue is channels and the extent of a lake if it were filled to the −2395m\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$-2395~\mbox{m}$\end{document} contour, (c) modified from Fig. 14b in Schon et al. (2012); channel sands, scroll bars, and craters of the western Jezero delta, (d) Jezero crater (white star) mapped in Tanaka et al. (2014); HNt is Hesperian and Noachian transition unit; mNhm is middle Noachian highland massif unit; lHt is late Hesperian transition unit; mNh is middle Noachian highland unit, (e) a portion of area mapped by Goudge et al. (2015) annotated with their map unit labels; MT is mottled terrain, Fn is northern fan deposit, Fw is western fan deposit, LTF is light-toned floor unit, VF is volcanic floor unit, Ac is surficial debris cover, C is impact crater, Crw is crater rim and wall material, (f) valleys, inverted channel bodies, and point bar strata modified from Fig. 2a in Goudge et al. (2018), (g) a portion of Jezero and the surrounding area mapped in Sun and Stack (2020). Nnp1 is Noachian Nili Planum 1, Nnp2 is Noachian Nili Planum 2, Nle is Noachian lower etched, Nue is Noachian upper etched, Njf is Noachian Jezero floor, NHjf1 and NHjf2 are Noachian Hesperian Jezero fan 1 and 2, respectively, cr is crater rim, su is smooth undivided, and Aeb is Amazonian eolian bedforms
Previous mapping efforts in and around Jezero crater: (a) Inlet valleys, outlet valley, and western and northern fan deposits, modified from Fig. 1b in Fassett and Head (2005), (b) modified from Fig. 1c in Ehlmann et al. (2008); yellow is Northern delta, orange is Western delta, blue is channels and the extent of a lake if it were filled to the −2395m\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$-2395~\mbox{m}$\end{document} contour, (c) modified from Fig. 14b in Schon et al. (2012); channel sands, scroll bars, and craters of the western Jezero delta, (d) Jezero crater (white star) mapped in Tanaka et al. (2014); HNt is Hesperian and Noachian transition unit; mNhm is middle Noachian highland massif unit; lHt is late Hesperian transition unit; mNh is middle Noachian highland unit, (e) a portion of area mapped by Goudge et al. (2015) annotated with their map unit labels; MT is mottled terrain, Fn is northern fan deposit, Fw is western fan deposit, LTF is light-toned floor unit, VF is volcanic floor unit, Ac is surficial debris cover, C is impact crater, Crw is crater rim and wall material, (f) valleys, inverted channel bodies, and point bar strata modified from Fig. 2a in Goudge et al. (2018), (g) a portion of Jezero and the surrounding area mapped in Sun and Stack (2020). Nnp1 is Noachian Nili Planum 1, Nnp2 is Noachian Nili Planum 2, Nle is Noachian lower etched, Nue is Noachian upper etched, Njf is Noachian Jezero floor, NHjf1 and NHjf2 are Noachian Hesperian Jezero fan 1 and 2, respectively, cr is crater rim, su is smooth undivided, and Aeb is Amazonian eolian bedforms
… 
Examples of the margin fractured (M-f) unit: (a) blocky expression of the M-f, (b) low-relief expression of the M-f, (c) delta blocky (D-bl) unit overlying the M-f
Examples of the margin fractured (M-f) unit: (a) blocky expression of the M-f, (b) low-relief expression of the M-f, (c) delta blocky (D-bl) unit overlying the M-f
… 
Representative examples of the Jezero delta units: (a) delta blocky (D-bl) unit; inset shows individual blocks on the upper surface of the delta, (b) delta thinly layered (D-tnl) unit; inset highlights contorted layers, (c) delta thinly layered (D-tnl) unit exposed at the base of a remnant mound east of the Jezero delta; inset highlights layers within the remnant mound, (d) delta thickly layered (D-tkl) unit. (e) delta truncated curvilinear layered (D-tcl) unit, (f) delta layered rough (D-lr) unit comprising the fan deposit northeast of, and adjacent to, the Jezero delta
Representative examples of the Jezero delta units: (a) delta blocky (D-bl) unit; inset shows individual blocks on the upper surface of the delta, (b) delta thinly layered (D-tnl) unit; inset highlights contorted layers, (c) delta thinly layered (D-tnl) unit exposed at the base of a remnant mound east of the Jezero delta; inset highlights layers within the remnant mound, (d) delta thickly layered (D-tkl) unit. (e) delta truncated curvilinear layered (D-tcl) unit, (f) delta layered rough (D-lr) unit comprising the fan deposit northeast of, and adjacent to, the Jezero delta
… 
Units on the Jezero crater rim: (a) crater rim blocky unit (CR-bl), (b) crater rim breccia (Cr-br); inset shows individual light-toned blocks, (c) crater rim layered (Cr-l) unit; inset shows faulting within the Cr-l unit, (d) crater rim rough (Cr-r) unit
Units on the Jezero crater rim: (a) crater rim blocky unit (CR-bl), (b) crater rim breccia (Cr-br); inset shows individual light-toned blocks, (c) crater rim layered (Cr-l) unit; inset shows faulting within the Cr-l unit, (d) crater rim rough (Cr-r) unit
… 
Units within Neretva Vallis and on Nili Planum: (a) Occurrences of Neretva Vallis layered (NV-l) unit within Neretva Vallis shown in (b) and (c), (b) exposure of NV-l just inside the rim of Jezero crater, (c) another exposure of NV-l within Neretva Vallis outside of Jezero crater, (d) low-relief expression of the Nili Planum fractured (NP-f) unit, (e) blocky, ridged expression of the NP-f
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Units within Neretva Vallis and on Nili Planum: (a) Occurrences of Neretva Vallis layered (NV-l) unit within Neretva Vallis shown in (b) and (c), (b) exposure of NV-l just inside the rim of Jezero crater, (c) another exposure of NV-l within Neretva Vallis outside of Jezero crater, (d) low-relief expression of the Nili Planum fractured (NP-f) unit, (e) blocky, ridged expression of the NP-f
… 
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Space Sci Rev (2020) 216:127
https://doi.org/10.1007/s11214-020-00739-x
Photogeologic Map of the Perseverance Rover Field Site
in Jezero Crater Constructed by the Mars 2020 Science
Team
Kathryn M. Stack1·Nathan R. Williams1·Fred Calef III1·Vivian Z. Sun1·
Kenneth H. Williford1·Kenneth A. Farley2·Sigurd Eide3·David Flannery4·
Cory Hughes5·Samantha R. Jacob6·Linda C. Kah7·Forrest Meyen8·
Antonio Molina9·Cathy Quantin Nataf10 ·Melissa Rice4·Patrick Russell11 ·
Eva Scheller2·Christina H. Seeger5·William J. Abbey1·Jacob B. Adler12 ·
Hans Amundsen13 ·Ryan B. Anderson14 ·Stanley M. Angel15 ·Gorka Arana16 ·
James Atkins7·Megan Barrington17 ·Tor B erge r18 ·Rose Borden7·Beau Boring7·
Adrian Brown19 ·Brandi L. Carrier1·Pamela Conrad20 ·Henning Dypvik3·
Sarah A. Fagents21 ·Zachary E. Gallegos22 ·Brad Garczynski23 ·
Keenan Golder7·Felipe Gomez9·Yulia Goreva1·Sanjeev Gupta24 ·
Svein-Erik Hamran3·Taryn Hic ks7·Eric D. Hinterman25 ·Briony N. Horgan23 ·
Joel Hurowitz26 ·Jeffrey R. Johnson27 ·Jeremie Lasue28 ·Rachel E. Kronyak1·
Yang Liu1·Juan Manuel Madariaga16 ·Nicolas Mangold29 ·John McClean24 ·
Noah Miklusicak7·Daniel Nunes1·Corrine Rojas6·Kirby Runyon27 ·
Nicole Schmitz30 ·Noel Scudder23 ·Emily Shaver7·Jason SooHoo25 ·
Russell Spaulding7·Evan Stanish31 ·Leslie K. Tamppari1·Michael M. Tice32 ·
Nathalie Turenne31 ·Peter A. Willis1·R. Aileen Yingst33
Received: 20 April 2020 / Accepted: 25 September 2020 / Published online: 3 November 2020
© Springer Nature B.V. 2020
Abstract The Mars 2020 Perseverance rover landing site is located within Jezero crater,
a∼50 km diameter impact crater interpreted to be a Noachian-aged lake basin inside the
The Mars 2020 Mission
Edited by Kenneth A. Farley, Kenneth H. Williford and Kathryn M. Stack
Electronic supplementary material The online version of this article
(https://doi.org/10.1007/s11214-020-00739-x) contains supplementary material, which is available to
authorized users.
BK.M. Stack
kathryn.m.stack@jpl.nasa.gov
1Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena,
CA 91109, USA
2California Institute of Technology, Pasadena, CA, USA
3University of Oslo, Oslo, Norway
4Queensland University of Technology, Brisbane, Queensland, Australia
5Western Washington University, Bellingham, WA, USA
6Arizona State University, Tempe, AZ, USA
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... We identify organics and aqueously formed minerals at Jezero crater in three rock targets (8) analyzed during the first 208 Martian days of the mission (Fig. 1) located in two different geological units within the floor of Jezero crater (9,12). The Garde target is from the altered ultramafic Séítah Formation (Fm), orbitally mapped as the Crater Floor Fractured 1 unit (CF-f1) ( Fig. 1) (9,12). ...
... We identify organics and aqueously formed minerals at Jezero crater in three rock targets (8) analyzed during the first 208 Martian days of the mission (Fig. 1) located in two different geological units within the floor of Jezero crater (9,12). The Garde target is from the altered ultramafic Séítah Formation (Fm), orbitally mapped as the Crater Floor Fractured 1 unit (CF-f1) ( Fig. 1) (9,12). The Guillaumes and Bellegarde targets are from the overlying and therefore younger basaltic Máaz Fm, orbitally mapped as the ~2.3-2.6 Ga (13) Crater Floor Fractured Rough unit (CF-fr) (9,12). ...
... The Garde target is from the altered ultramafic Séítah Formation (Fm), orbitally mapped as the Crater Floor Fractured 1 unit (CF-f1) ( Fig. 1) (9,12). The Guillaumes and Bellegarde targets are from the overlying and therefore younger basaltic Máaz Fm, orbitally mapped as the ~2.3-2.6 Ga (13) Crater Floor Fractured Rough unit (CF-fr) (9,12). The Perseverance rover drilled four rock samples from the Séítah Fm. ...
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... VF unit thickness was previously constrained from orbital topography data to be 13 ± 0.8 m from profile measurements around the margins of the unit (Shahrzad et al., 2019). The LTF unit (Cf-f-1 in Stack et al., 2020) consists of blocky light-toned bedrock intermixed with darker sands and light-toned aeolian bedforms associated with olivine and Mg-rich carbonate from orbit (Goudge et al., 2015) and exhibits a range of negative and positive topography . In contrast, the darker-toned VF unit (Cf-fr in Stack et al., 2020) has a more constrained topographic range, is smoother, retains a large number of impact craters, and has weak pyroxene absorption features in orbital data (Ehlmann et al., 2008;Goudge et al., 2015;Horgan et al., 2020;Stack et al., 2020). ...
... The LTF unit (Cf-f-1 in Stack et al., 2020) consists of blocky light-toned bedrock intermixed with darker sands and light-toned aeolian bedforms associated with olivine and Mg-rich carbonate from orbit (Goudge et al., 2015) and exhibits a range of negative and positive topography . In contrast, the darker-toned VF unit (Cf-fr in Stack et al., 2020) has a more constrained topographic range, is smoother, retains a large number of impact craters, and has weak pyroxene absorption features in orbital data (Ehlmann et al., 2008;Goudge et al., 2015;Horgan et al., 2020;Stack et al., 2020). In places the VF unit is covered by smooth undifferentiated material interpreted to be an accumulated lag from deflation of local bedrock . ...
... The LTF unit (Cf-f-1 in Stack et al., 2020) consists of blocky light-toned bedrock intermixed with darker sands and light-toned aeolian bedforms associated with olivine and Mg-rich carbonate from orbit (Goudge et al., 2015) and exhibits a range of negative and positive topography . In contrast, the darker-toned VF unit (Cf-fr in Stack et al., 2020) has a more constrained topographic range, is smoother, retains a large number of impact craters, and has weak pyroxene absorption features in orbital data (Ehlmann et al., 2008;Goudge et al., 2015;Horgan et al., 2020;Stack et al., 2020). In places the VF unit is covered by smooth undifferentiated material interpreted to be an accumulated lag from deflation of local bedrock . ...
Elevation Anomalies of the Volcanic Floor Unit and Their Relationships to the Multiple Lakes of Jezero Crater, Mars
Article
Full-text available
We reassessed several orbital topographic data sets for the Perseverance rover landing site at Jezero Crater, Mars to better understand its floor units. Tens‐of‐meters deep topographic anomalies occur in the volcanic floor of Jezero crater and are not a result of impact cratering. Eight km‐scale steep escarpment‐bounded depressions may be locations of paleotopographic highs that were embayed by the volcanic floor lava flows, forming inverted topography from either contemporaneous upward inflation of embaying lavas or later deep scour due to differential erosion over 10⁷⁻⁹ years. Five multi km‐scale shallow‐sloped depressions linked by channel‐like forms may record locations of buried paleolakes and channels that predate the volcanic floor units or a drained magma system. These results indicate Jezero experienced multiple closed‐basin or dry phases, allowing erosion of the crater floor and creation of topography, which provides new geologic context for the samples gathered by Perseverance.
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... The western fan is the largest and best preserved of the two; it sits at the mouth of the largest and deepest breach in the crater rim and is connected to Neretva Vallis (Figure 1), which is inferred to be the source of most of the detrital material in the fan (e.g., Salese et al., 2020). What remains of the fan today covers an area of about 35 km 2 , and displays a variety of morphologies at its surface, including channel belt structures, suggesting a polyphase depositional history (e.g., Kronyak et al., 2023;Stack et al., 2020). By landing in Jezero crater in February 2021 the Perseverance rover (and companion Ingenuity helicopter), the Mars 2020 mission was offered an unprecedented opportunity to obtain ground-based data relating to the vertical and horizontal successions of the orbitally defined western fan. ...
... The similar elevation and erosional expression observed on both the butte and the main fan (e.g., Gupta et al., 2022;Mangold et al., 2021;Mangold et al., 2024) suggests Kodiak as an erosional remnant that has been isolated from the main fan (cf. Stack et al., 2020). Mangold et al. (2021) were the first to use Perseverance's ground-based images of the fan front to characterize the sedimentary architecture and morphology visible at the outcrop-scale. ...
Depositional Facies and Sequence Stratigraphy of Kodiak Butte, Western Delta of Jezero Crater, Mars
Article
Full-text available
  • Apr 2024
High‐resolution 2D and 3D data remotely acquired by SuperCam's Remote Micro‐Imager and Mastcam‐Z aboard the Perseverance rover enabled us to characterize the stratigraphic architecture and sedimentary record of the Kodiak butte, an isolated remnant of the western delta fan of Jezero crater. Using these data, we build up on previous interpretations of the butte interpreted as a prograding Gilbert‐type deltaic series. We characterize three individual stratigraphic Units 0 to 2 on the eastern and northern faces of the butte. Each Unit displays the same vertical succession of prodeltaic/lacustrine bottomsets, delta slope toesets and foresets, and fluvially influenced topsets of a deltaic plain with a braided river pattern, shown by 11 individual sedimentary facies. We infer that these individual Units record the formation of three distinct deltaic mouth bars successively across time and space. For the first time on another planet than Earth, we are able to construct a precise sequence stratigraphic framework to highlight lake‐level fluctuations at the time the Kodiak butte was emplaced, during the latest stages of deltaic activity. We identify four hydrogeological cycles indicated by alternating rises and falls of the lake‐level on the order of 5–10 m. These were most probably linked to climatic events and variations controlling lake water inputs in probable relation to an astronomical control.
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... On Mars 2020 mission sol 380 (a sol is a martian day), Perseverance completed the Crater Floor Campaign. In situ observations of the lithology, stratigraphy, and mineralogy using the Perseverance payload enabled the redefinition of the original crater units (defined from orbital data by Stack et al., 2020) as the Séítah formation (formerly Cf-f-1) and the Máaz formation (formerly Cf-fr) Sun et al., 2023). The Séítah formation is interpreted to be an olivine cumulate carbonated under low water/rock conditions Liu et al., 2022;Scheller et al., 2022;Tice et al., 2022) and includes multiple layers of varying composition. ...
Evidence of Sulfate‐Rich Fluid Alteration in Jezero Crater Floor, Mars
Article
Full-text available
  • Jan 2024
Sulfur plays a major role in martian geochemistry and sulfate minerals are important repositories of water. However, their hydration states on Mars are poorly constrained. Therefore, understanding the hydration and distribution of sulfate minerals on Mars is important for understanding its geologic, hydrologic, and atmospheric evolution as well as its habitability potential. NASA's Perseverance rover is currently exploring the Noachian‐age Jezero crater, which hosts a fan‐delta system associated with a paleolake. The crater floor includes two igneous units (the Séítah and Máaz formations), both of which contain evidence of later alteration by fluids including sulfate minerals. Results from the rover instruments Scanning Habitable Environments with Raman and Luminescence for Organics and Chemistry and Planetary Instrument for X‐ray Lithochemistry reveal the presence of a mix of crystalline and amorphous hydrated Mg‐sulfate minerals (both MgSO4·[3–5]H2O and possible MgSO4·H2O), and anhydrous Ca‐sulfate minerals. The sulfate phases within each outcrop may have formed from single or multiple episodes of water activity, although several depositional events seem likely for the different units in the crater floor. Textural and chemical evidence suggest that the sulfate minerals most likely precipitated from a low temperature sulfate‐rich fluid of moderate pH. The identification of approximately four waters puts a lower constraint on the hydration state of sulfate minerals in the shallow subsurface, which has implications for the martian hydrological budget. These sulfate minerals are key samples for future Mars sample return.
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... To visualize the phyllosilicates that are present in the olivine rich unit, we have produced a map of the orbital CRISM Half Resolution Long (HRL) image, HRL000040FF, over Jezero crater (Figure 6). This includes the area of Mars 2020 operations, Octavia E. Butler Landing site, Jezero Delta, and the Margin Carbonates region (Williford et al., 2018;Horgan et al., 2020;Farley et al., 2020;Stack et al., 2020). Alongside a 0.905 μm channel image, we have included three absorption band maps from the CRISM image for 2.31 μm (phyllosilicate and carbonate), 2.5 μm (carbonate) and 2.38 μm (phyllosilicate). ...
Properties of the Nili Fossae Olivine-rich lithology: orbital and in situ at Séítah
Preprint
  • Nov 2023
We have studied the properties of the Nili Fossae olivine lithology from orbital data and in situ by the Mars 2020 rover at the Séítah unit in Jezero crater. We used the geochemistry collected by the rover’s instruments to calculate the viscosity and relative flow distance of the Séítah unit. Based on the low viscosity and distribution of the unit we postulate a ponded lava flow origin for the olivine rich unit at Séítah. We calculate an approximate depth for the cumulate layer of the lava pond based on the viscosity of the unit and model of Worster et al. (1993). We show that the resolution of orbital data is inadequate to map the phyllosilicate 2.38 μm band and demonstrate that it can be supplemented by in situ data from Mars 2020 SuperCam Laser Induced Breakdown Spectroscopy (LIBS) and reflectance observations to show that the low Al phyllosilicate in the olivine cumulate in the Séítah formation is either talc, serpentine, hectorite, Fe/Mg smectite, saponite or stevensite. We discuss two intertwining aspects of the history of the lithology: 1) the potential emplacement and properties of the cumulate layer within a ponded lava flow, using previously published models of ponded lava flows and lava lakes, and 2) the limited extent of post emplacement alteration, including phyllosilicate and carbonate alteration.
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Investigating Microbial Biosignatures in Aeolian Environments Using Micro-X-Ray: Simulation of PIXL Instrument Analyses at Jezero Crater Onboard the Perseverance Mars 2020 Rover
Article
  • May 2024
  • ASTROBIOLOGY
Assessing the past habitability of Mars and searching for evidence of ancient life at Jezero crater via the Perseverance rover are the key objectives of NASA's Mars 2020 mission. Onboard the rover, PIXL (Planetary Instrument for X-ray Lithochemistry) is one of the best suited instruments to search for microbial biosignatures due to its ability to characterize chemical composition of fine scale textures in geological targets using a nondestructive technique. PIXL is also the first micro-X-ray fluorescence (XRF) spectrometer onboard a Mars rover. Here, we present guidelines for identifying and investigating a microbial biosignature in an aeolian environment using PIXL-analogous micro-XRF (μXRF) analyses. We collected samples from a modern wet aeolian environment at Padre Island, Texas, that contain buried microbial mats, and we analyzed them using μXRF techniques analogous to how PIXL is being operated on Mars. We show via μXRF technique and microscope images the geochemical and textural variations from the surface to ∼40 cm depth. Microbial mats are associated with heavy-mineral lags and show specific textural and geochemical characteristics that make them a distinct biosignature for this environment. Upon burial, they acquire a diffuse texture due to the expansion and contraction of gas-filled voids, and they present a geochemical signature rich in iron and titanium, which is due to the trapping of heavy minerals. We show that these intrinsic characteristics can be detected via μXRF analyses, and that they are distinct from buried abiotic facies such as cross-stratification and adhesion ripple laminations. We also designed and conducted an interactive survey using the Padre Island μXRF data to explore how different users chose to investigate a biosignature-bearing dataset via PIXL-like sampling strategies. We show that investigating biosignatures via PIXL-like analyses is heavily influenced by technical constraints (e.g., the XRF measurement characteristics) and by the variety of approaches chosen by different scientists. Lessons learned for accurately identifying and characterizing this biosignature in the context of rover-mission constraints include defining relative priorities among measurements, favoring a multidisciplinary approach to the decision-making process of XRF measurements selection, and considering abiotic results to support or discard a biosignature interpretation. Our results provide guidelines for PIXL analyses of potential biosignature on Mars.
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The high-resolution map of Oxia Planum, Mars; the landing site of the ExoMars Rosalind Franklin rover mission
Article
This 1:30,000 scale geological map describes Oxia Planum, Mars, the landing site for the ExoMars Rosalind Franklin rover mission. The map represents our current understanding of bedrock units and their relationships prior to Rosalind Franklin’s exploration of this location. The map details 15 bedrock units organised into 6 groups and 7 textural and surficial units. The bedrock units were identified using visible and near-infrared remote sensing datasets. The objectives of this map are (i) to identify where the most astrobiologically relevant rocks are likely to be found, (ii) to show where hypotheses about their geological context (within Oxia Planum and in the wider geological history of Mars) can be tested, (iii) to inform both the long-term (hundreds of metres to ∼1 km) and the short-term (tens of metres) activity planning for rover exploration, and (iv) to allow the samples analysed by the rover to be interpreted within their regional geological context.
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Architecture of Fluvial and Deltaic Deposits Exposed Along the Eastern Edge of the Western Fan of Jezero Crater, Mars
Article
Full-text available
  • Mar 2024
Early observations from the Perseverance rover suggested a deltaic origin for the western fan of Jezero crater only from images of the Kodiak butte. Here, we use images from the SuperCam Remote Micro‐Imager and the Mastcam‐Z camera to analyze the western fan front along the rover traverse, and further assess its depositional origin. Outcrops in the middle to lower half of the hillslopes comprise planar and inclined beds of sandstone that are interpreted as foresets of deltaic deposits. Foresets are locally structured in ∼20–25 m thick, ∼80–100 m long, antiformal structures interpreted as deltaic mouth bars. Above these foresets, interbedded sandstones and boulder conglomerates are interpreted as fluvial topset beds. One well‐preserved lens of boulder conglomerate displays rounded clasts within well‐sorted sediment deposited in overall fining upward beds. We interpret these deposits as resulting from lateral accretion within fluvial channels. Estimations of peak discharge rates give a range between ∼100 and ∼500 m³ s⁻¹. By contrast, boulder conglomerates exposed in the uppermost part of hillslopes are poorly sorted and truncate the underlying beds. The presence of these boulder deposits suggests that intense sediment‐laden flood episodes occurred after the deltaic foreset and topset beds were deposited, although the origin, timing, and relationship of these boulder deposits to the ancient lake that once filled Jezero crater remains undetermined. Overall, these observations confirm the deltaic nature of the fan front, and suggest a highly variable fluvial input.
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Sedimentology and Stratigraphy of the Shenandoah Formation, Western Fan, Jezero Crater, Mars
Article
Full-text available
  • Feb 2024
Sedimentary fans are key targets of exploration on Mars because they record the history of surface aqueous activity and habitability. The sedimentary fan extending from the Neretva Vallis breach of Jezero crater's western rim is one of the Mars 2020 Perseverance rover's main exploration targets. Perseverance spent ∼250 sols exploring and collecting seven rock cores from the lower ∼25 m of sedimentary rock exposed within the fan's eastern scarp, a sequence informally named the “Shenandoah” formation. This study describes the sedimentology and stratigraphy of the Shenandoah formation at two areas, “Cape Nukshak” and “Hawksbill Gap,” including a characterization, interpretation, and depositional framework for the facies that comprise it. The five main facies of the Shenandoah formation include: laminated mudstone, laminated sandstone, low‐angle cross stratified sandstone, thin‐bedded granule sandstone, and thick‐bedded granule‐pebble sandstone and conglomerate. These facies are organized into three facies associations (FA): FA1, comprised of laminated and soft sediment‐deformed sandstone interbedded with broad, unconfined coarser‐grained granule and pebbly sandstone intervals; FA2, comprised predominantly of laterally extensive, soft‐sediment deformed laminated, sulfate‐bearing mudstone with lenses of low‐angle cross‐stratified and scoured sandstone; and FA3, comprised of dipping planar, thin‐bedded sand‐gravel couplets. The depositional model favored for the Shenandoah formation involves the transition from a sand‐dominated distal alluvial fan setting (FA1) to a stable, widespread saline lake (FA2), followed by the progradation of a river delta system (FA3) into the lake basin. This sequence records the initiation of a relatively long‐lived, habitable lacustrine and deltaic environment within Jezero crater.
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Ground penetrating radar observations of the contact between the western delta and the crater floor of Jezero crater, Mars
Article
  • Jan 2024
The delta deposits in Jezero crater contain sedimentary records of potentially habitable conditions on Mars. NASA’s Perseverance rover is exploring the Jezero western delta with a suite of instruments that include the RIMFAX ground penetrating radar, which provides continuous subsurface images that probe up to 20 meters below the rover. As Perseverance traversed across the contact between the Jezero crater floor and the delta, RIMFAX detected a distinct discontinuity in the subsurface layer structure. Below the contact boundary are older crater floor units exhibiting discontinuous inclined layering. Above the contact boundary are younger basal delta units exhibiting regular horizontal layering. At one location, there is a clear unconformity between the crater floor and delta layers, which implies that the crater floor experienced a period of erosion before the deposition of the overlying delta strata. The regularity and horizontality of the basal delta sediments observed in the radar cross sections indicate that they were deposited in a low-energy lake environment.
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Olivine‐Carbonate Mineralogy of the Jezero Crater Region
Article
Full-text available
  • Feb 2020
A well‐preserved, ancient delta deposit, in combination with ample exposures of carbonate outcrops, makes Jezero Crater in Nili Fossae a compelling astrobiological site. We use Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) observations to characterize the surface mineralogy of the crater and surrounding watershed. Previous studies have documented the occurrence of olivine and carbonates in the Nili Fossae region. We focus on correlations between these two well‐studied lithologies in the Jezero crater watershed. We map the position and shape of the olivine 1 μm absorption band and find that carbonates are found in association with olivine which displays a 1 μm band shifted to long wavelengths. We then use Thermal Emission Imaging Spectrometer (THEMIS) coverage of Nili Fossae and perform tests to investigate whether the long wavelength shifted (redshifted) olivine signature is correlated with high thermal inertia outcrops. We find that there is no consistent correlation between thermal inertia and the unique olivine signature. We discuss a range of formation scenarios for the olivine and carbonate associations, including the possibility that these lithologies are products of serpentinization reactions on early Mars. These lithologies provide an opportunity for deepening our understanding of early Mars and, given their antiquity, may provide a framework to study the timing of valley networks and the thermal history of the Martian crust and interior from the early Noachian to today.
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The mineral diversity of Jezero crater: Evidence for possible lacustrine carbonates on Mars
Article
Full-text available
  • Nov 2019
Noachian-aged Jezero crater is the only known location on Mars where clear orbital detections of carbonates are found in close proximity to clear fluvio-lacustrine features indicating the past presence of a paleolake; however, it is unclear whether or not the carbonates in Jezero are related to the lacustrine activity. This distinction is critical for evaluating the astrobiological potential of the site, as lacustrine carbonates on Earth are capable of preserving biosignatures at scales that may be detectable by a landed mission like the Mars 2020 rover, which is planned to land in Jezero in February 2021. In this study, we conduct a detailed investigation of the mineralogical and morphological properties of geological units within Jezero crater in order to better constrain the origin of carbonates in the basin and their timing relative to fluvio-lacustrine activity. Using orbital visible/near-infrared hyperspectral images from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) along with high resolution imagery and digital elevation models, we identify a distinct carbonate-bearing unit, the “Marginal Carbonates,” located along the inner margin of the crater, near the largest inlet valley and the western delta. Based on their strong carbonate signatures, topographic properties, and location in the crater, we propose that this unit may preserve authigenic lacustrine carbonates, precipitated in the near-shore environment of the Jezero paleolake. Comparison to carbonate deposits from terrestrial closed basin lakes suggests that if the Marginal Carbonates are lacustrine in origin, they could preserve macro- and microscopic biosignatures in microbialite rocks like stromatolites, some of which would likely be detectable by Mars 2020. The Marginal Carbonates may represent just one phase of a complex fluvio-lacustrine history in Jezero crater, as we find that the spectral diversity of the fluvio-lacustrine deposits in the crater is consistent with a long-lived lake system cataloging the deposition and erosion of regional geologic units. Thus, Jezero crater may contain a unique record of the evolution of surface environments, climates, and habitability on early Mars.
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Refining the age, emplacement and alteration scenarios of the olivine-rich unit in the Nili Fossae region, Mars
Article
Full-text available
  • Jan 2020
The Nili Fossae region of Mars exhibits from remote sensing spectral data the largest exposures of olivine-rich materials on the planet. However, it is not clearly constrained how and when these terrains formed. Some of the proposed scenarios favor a mode of formation closely related to Isidis impact basin: either under intense effusive volcanism following the impact, from cooling of an immediate impact melt sheet or silicate impact vapor condensate. These deposits might also be pyroclastic products ejected from now eroded or buried vents. Recent studies also proposed that lag deposits could be responsible for enrichment in olivine after deposition. In this contribution, we mapped the olivine-rich unaltered and altered bedrock exposures using near infrared and thermal inertia data, investigated the geometry and key contacts of the olivine-rich unit, and determined its surface age using crater counts and stratigraphical relationships. We find that the olivine-rich bedrock extends over at least ~18,000 km2 in the Nili Fossae region, with a large part of it being unaltered. Olivine-rich material that overlaps the northern rim of Jezero crater corresponds to a primary deposit (i.e. rather than reworked material). Since this crater is younger than Isidis, we favor the hypothesis of a post-Isidis origin, rather than the impact melt (consistently with Bramble et al., 2017) and impact condensate origin. Based on our observations and crater counts, we estimate an emplacement age of 3.82 ± 0.07 Ga (Mid to Late Noachian). We discuss the origin of the unit, with the most likely scenarios being ash falls and/or pyroclastic surges. To explain the circum-Isidis distribution of these deposits, we favor the hypothesis of a thinned and weakened crust in the region subsequently to the giant impact of Isidis, as suggested by Tornabene et al. (2008). Finally, the distribution of altered bedrock conflicts with the contact metamorphism scenario. As the olivine-rich unit exposed at Jezero crater, future home of the Mars 2020 rover, is a regional stratigraphic marker, return samples for precise dating of this unit should be made one of the major mission targets.
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Wind in Jezero Crater, Mars
Article
Full-text available
Wind generates erosional and depositional morphologies across Mars, including in Jezero crater, the planned landing site for the Mars 2020 rover. Known for subaqueously formed sedimentary features, Jezero crater also hosts wind-formed features that provide insights about the local wind regime. We combine interpretations from dunes, wind streaks, transverse aeolian ridges, and yardangs to holistically understand the recent history of wind in Jezero crater. Together, these features describe modern easterly winds trending toward 263° ± 8° and older southwesterly winds that formed small yardangs. Previous research has suggested that aeolian processes eroded the delta deposit in Jezero crater. We propose early southwesterly winds removed the majority of material, exposing the more lithified units seen today. Modern easterly winds continue to cause erosion, but lithologic heterogeneities remain the dominant control on delta deposit evolution. Aeolian erosion has accentuated existing sedimentary structures, leaving the striking delta remnant seen today.
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Crater Statistics on the Dark-Toned, Mafic Floor Unit in Jezero Crater, Mars
Article
Full-text available
Plain Language Summary Jezero crater is a large impact crater on Mars with a diameter of about 45 km. In the Martian deep past this crater hosted a long‐lived lake. On 19 November NASA announced that Jezero crater will be the landing site for the coming Mars 2020 mission. On top of sediments on the central crater floor is a distinctive deposit of dark rocks that possibly originated as a lava flow after the lake had dried out. We studied the statistics of small impact craters on this dark deposit. Such impact crater statistic is widely used as a tool for dating Martian terrains. We report a derived “model age” of 2.6 ± 0.2 Ga for these rocks. One central goal of the Mars 2020 mission is to select and store a cache of rock samples that will be returned to Earth by a later mission for study in terrestrial laboratories. If this dark deposit is indeed lava, a sample could be dated in terrestrial laboratories. Together with our crater statistics reported here, this could provide a crucial tie‐point for recalibration of the crater count dating system for Mars, which now relies on extrapolation from samples collected on the Moon.
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The science process for selecting the landing site for the 2020 Mars rover
Article
Full-text available
  • Jul 2018
  • PLANET SPACE SCI
The process of identifying the landing site for NASA's Mars 2020 rover began in 2013 by defining threshold mission science criteria related to seeking signs of ancient habitable conditions, searching for biosignatures of past microbial life, assembling a returnable cache of samples for possible future return to Earth, and collecting data for planning eventual human missions to the surface of Mars. Mission engineering constraints on elevation and latitude were used to identify candidate landing sites that addressed the scientific objectives of the mission. However, for the first time these constraints did not have a major influence on the viability of candidate sites and, with the new entry, descent, and landing capabilities included in the baseline mission, the vast majority of sites were evaluated and down-selected on the basis of science merit. More than 30 candidate sites with likely acceptable surface and atmospheric conditions were considered at a series of open workshops in the years leading up to the launch. During that period, iteration between engineering constraints and the evolving relative science potential of candidate sites led to the identification of three final candidate sites: Jezero crater (18.4386°N, 77.5031°E), northeast (NE) Syrtis (17.8899°N,77.1599°E) and Columbia Hills (14.5478°S, 175.6255°E). The final landing site will be selected by NASA's Associate Administrator for the Science Mission Directorate. This paper serves as a record of landing site selection activities related primarily to science, an inventory of the number and variety of sites proposed, and a summary of the science potential of the highest-ranking sites.
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Impact cratering as a cause of climate change, surface alteration, and resurfacing during the early history of Mars
Article
  • Apr 2018
Ancient valley networks (VNs) and related open‐ and closed‐basin lakes are testimony to the presence of flowing liquid water on the surface of Mars in the Late Noachian and Early Hesperian. Uncertain, however, has been the mechanism responsible for causing the necessary rainfall and runoff and/or snowfall and subsequent melting. Impact cratering has been proposed (e.g., Segura et al. 2002) as a process for temporarily raising temperatures and inducing conditions that would produce rainfall, snowmelt, runoff, and formation of the VNs and associated lacustrine features. We refer to the collective effects of this process as the ICASE model (impact cratering atmospheric/surface effects). In this contribution, we assess the proposed impact cratering mechanism in order to understand its climatic implications for early Mars: we outline the step‐by‐step events in the cratering process and explore the predictions for atmospheric and surface geological consequences. For large and basin‐scale impacts, rainfall should be globally and homogeneously distributed and characterized by very high temperatures. Rainfall rates are predicted to be high, ~2 m yr−1, similar to rates in tropical rainforests on Earth, and runoff rates are correspondingly very high. These predicted characteristics do not seem to be consistent with the observed VNs, which are mainly equatorial and not homogeneous in their distribution. Prior to the Late Noachian, however, we predict that basin‐scale impact effects are very likely to contribute significantly to degradation of crater rims and regional smoothing of terrain, implying vast resurfacing and resetting of crater ages following large crater and basin‐scale impacts. Furthermore, the high temperatures of impact‐induced rainwater and snowmelt and the pervasive penetration of heat into the regolith substrate are predicted to have a significant influence on the mineralogical alteration of the crust and its resulting physical properties. We conclude by describing a case example (Isidis basin) and describe how the ICASE model provides an alternative scenario for the interpretation of the layered phyllosilicates in the Nili Fossae and NE Sytris regions. We outline specific conclusions and recommendations designed to improve the ICASE model and to promote further understanding of its implications for the geological, mineralogical, and climate history of early Mars.
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Areally Extensive Surface Bedrock Exposures on Mars: Many Are Clastic Rocks, Not Lavas
Article
  • Feb 2018
Areally extensive exposures of intact olivine/pyroxene-enriched rock, as well as feldspar-enriched rock, are found in isolated locations throughout the Martian highlands. The petrogenetic origin(s) of these rock units are not well understood, but some previous studies favored an effusive volcanic origin partly on the basis of distinctive composition and relatively high thermal inertia. Here we show that the regolith development, crater retention, and morphological characteristics for many of these “bedrock plains” are not consistent with competent lavas, and reinterpret the high thermal inertia orbital signatures to represent friable materials that are more easily kept free of comminution products through aeolian activity. Candidate origins include pyroclastic rocks, impact-generated materials, or detrital sedimentary rocks. Olivine/pyroxene enrichments in bedrock plains relative to surrounding materials could have potentially formed through deflation and preferential removal of plagioclase.
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