Sedimentology and Stratigraphy of the Shenandoah Formation, Western Fan, Jezero Crater, Mars

Kathryn M Stack (1) , Libby R W Ives (1, 2) , Sanjeev Gupta (3) , Michael P Lamb (4, 2) , Michelle Tebolt (1, 5) , Gwénaël Caravaca (6) , John P Grotzinger (7) , Patrick Russell (8) , David L Shuster (9) , Amy J Williams (10) , Hans Amundsen (11) , Sanna Alwmark (12, 13) , Andrew M Annex (7) , Robert Barnes (3) , James Bell (14) , O. Beyssac (15) , Tanja Bosak (16) , Larry S Crumpler (17) , Erwin Dehouck (18) , Samantha J Gwizd (1, 2) , Keyron Hickman‐lewis (19, 20) , Briony H N Horgan (21) , Joel Hurowitz (22) , Hemani Kalucha (4) , Oak Kanine (4) , Connor Lesh (1, 23) , Justin Maki (1, 2) , N. Mangold (24) , Nicolas Randazzo (25) , Christina Seeger (4) , Rebecca M E Williams (26) , Adrian Brown (27) , Emily Cardarelli (1, 23) , H. Dypvik (28) , David Flannery (29) , Jens Frydenvang (30) , S.‐E. Hamran (28) , Jorge I Núñez (31) , David Paige (23) , Justin I Simon (32) , Michael M Tice (33) , Christian Tate (34) , Roger C Wiens (21)

1 JPL - Jet Propulsion Laboratory
2 Stanford University
3 Department of Earth Science and Engineering [Imperial College London]
4 CALTECH - California Institute of Technology
5 JSG - Jackson School of Geosciences
6 IRAP - Institut de recherche en astrophysique et planétologie
7 Division of Geological and Planetary Sciences [Pasadena]
8 IAP - Institut d'Astrophysique de Paris
9 EPS - Department of Earth and Planetary Science [UC Berkeley]
10 UF|Geological - Department of Geological Sciences [Gainesville]
11 PGP - Physics of Geological Processes [Oslo]
12 Skane University Hospital [Lund]
13 ITU - IT University of Copenhagen
14 SESE - ASU School of Earth and Space Exploration
15 IMPMC - Institut de minéralogie, de physique des matériaux et de cosmochimie
16 EAPS - Department of Earth, Atmospheric and Planetary Sciences [MIT, Cambridge]
17 NMMNHS - New Mexico Museum of Natural History and Science
18 LGL-TPE - Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement
19 NHM - The Natural History Museum [London]
20 Dipartimento di Scienze Biologiche, Geologiche e Ambientali [Bologna]
21 EAPS - Department of Earth, Atmospheric, and Planetary Sciences [West Lafayette]
22 Department of Geosciences [Stony Brook]
23 UCLA - University of California [Los Angeles]
24 LPG - Laboratoire de Planétologie et Géosciences [UMR_C 6112]
25 UBC EOAS - Department of Earth, Ocean and Atmospheric Sciences [Vancouver]
26 PSI - Planetary Science Institute [Tucson]
27 Plancius Research LLC
28 UiO - University of Oslo
29 QUT - Queensland University of Technology [Brisbane]
30 UCPH - University of Copenhagen = Københavns Universitet
31 APL - Johns Hopkins University Applied Physics Laboratory [Laurel, MD]
32 JSC - NASA Johnson Space Center
33 Texas A&M University [College Station]
34 CU - Cornell University [Ithaca]

Abstract 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.

Mots clés: Mars; mars 2020; jezero crater; shenandoah formation; delta; perseverance; paleoenvironment

Domaines: Planétologie et astrophysique de la terre [astro-ph.EP]; Stratigraphie

Kathryn M Stack, Libby R W Ives, Sanjeev Gupta, Michael P Lamb, Michelle Tebolt, et al.. Sedimentology and Stratigraphy of the Shenandoah Formation, Western Fan, Jezero Crater, Mars. Journal of Geophysical Research. Planets, 2024, The Perseverance Rover's Exploration of the Western Fan Front, Jezero Crater, Mars, 129 (2), pp.e2023JE008187. ⟨10.1029/2023je008187⟩. ⟨hal-04521140⟩