Sedimentary architecture of the delta front at Jezero crater, Mars - Archive ouverte HAL
Communication Dans Un Congrès Année : 2023

Sedimentary architecture of the delta front at Jezero crater, Mars

Briony Horgan
Roger C Wiens

Résumé

The Perseverance rover landed on the floor of Jezero crater in February 2021, a site selected thanks to the presence of fluvial valleys, sedimentary fans and astrobiologically-relevant minerals (phyllosilicates, carbonates). Images obtained along the rover traverse by the Mastcam-Z camera and the SuperCam instrument provide in-situ observations of scarps along the western fan and the residual butte Kodiak. These images display a variety of facies consistent with a deltaic architecture: Close to the base of scarps of the butte Kodiak, subhorizontal, fine-grained layers are interpreted as bottomsets transitioning progressively into steeply inclined (up to 35°) planar beds interpreted as foresets. Above foresets, sandstones and pebbly sandstones display cross-bedding and local channelization as observed in fluvial deposits, interpreted as topsets on the deltaic plain. The transition from foresets to topsets display varying elevations (from -2510 to -2580 m below datum) suggestive of fluctuating lake levels in a closed lake system. Boulder-rich conglomerates are observed toward the top of scarps. They display a clast-supported texture with imbricated, rounded cobbles and ~1 m thick beds with fining upward sequence consistent with accretion of fluvial bars from high-energy floods of still undetermined origin (e.g., glacial dam break, rapid snowmelt). The persistence of a lake during these flood events is currently unknown. The overall architecture and presence of flood deposits suggest a building of the fan in relatively short period at geological scale in agreement with estimations made in the past (hundreds to thousands of years).
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Dates et versions

hal-04052771 , version 1 (30-03-2023)

Identifiants

  • HAL Id : hal-04052771 , version 1

Citer

Nicolas Mangold, Sanjeev Gupta, Gwénaël Caravaca, Gilles Dromart, Olivier Gasnault, et al.. Sedimentary architecture of the delta front at Jezero crater, Mars. International Conference on Fluvial Sedimentology 2023, Jul 2023, Riva Del Garda, Italy. ⟨hal-04052771⟩
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