Refining the age, emplacement and alteration scenarios of the olivine-rich unit in the Nili Fossae region, Mars

Mandon, Lucia; Quantin‐Nataf, Cathy; Thollot, P.; Mangold, N.; Lozac’h, L.; Dromart, G.; Beck, Pierre; Dehouck, E.; Breton, Sylvain; Millot, C.; Volat, Matthieu

doi:10.1016/j.icarus.2019.113436

Cited by 71 publications

(151 citation statements)

References 77 publications

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“…The olivine-rich unit clearly postdates the Noachian basement (Hoefen et al, 2003;Hamilton and Christensen, 2005;Mustard et al, 2008) and appears to drape the pre-existing topography in a region roughly bounded by Nili Fossae to the west and Isidis basin to the east (Ehlmann and Mustard, 2012;Bramble et al, 2017;Kremer et al, 2019;Mandon et al, 2020). Its age remains unclear, although Middle to Late Noachian is the most likely (Mandon et al, 2020.). Fluvial valleys cut the olivine-rich unit, but only those valleys that are poorly developed, braided, and channel like such as the lower section of the western valley and the northern valley.…”

Section: Chronological Relationships With Surrounding Landforms and Gmentioning

confidence: 95%

“…However, new studies interpret the olivine-bearing unit to be cemented ash deposits, especially based on the texture of this unit, which appears to be weak, and based on the fact that it does not retain well small-impact craters to erosion (Mandon et al, 2020). The moderate thermal inertia, the presence of yardangs and of a sparse regolith cover also indicate that the olivine-bearing unit is composed predominantly of friable clastic rocks (Bramble et al, 2017;Rogers et al, 2018;Kremer et al, 2019).…”

Section: Interpretation Of the Differences In Morphologymentioning

confidence: 99%

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Fluvial Regimes, Morphometry, and Age of Jezero Crater Paleolake Inlet Valleys and Their Exobiological Significance for the 2020 Rover Mission Landing Site

et al. 2020

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Jezero crater has been selected as the landing site for the Mars 2020 Perseverance rover, because it contains a paleolake with two fan-deltas, inlet and outlet valleys. Using the data from the High Resolution Stereo Camera (HRSC) and the High Resolution Imaging Science Experiment (HiRISE), we conducted a quantitative geomorphological study of the inlet valleys of the Jezero paleolake. Results show that the strongest erosion is related to a network of deep valleys that cut into the highland bedrock well upstream of the Jezero crater and likely formed before the formation of the regional olivine-rich unit. In contrast, the lower sections of valleys display poor bedrock erosion and a lack of tributaries but are characterized by the presence of pristine landforms interpreted as fluvial bars from preserved channels, the discharge rates of which have been estimated at 10 3-10 4 m 3 s-1. The valleys' lower sections postdate the olivine-rich unit, are linked directly to the fan-deltas, and are thus formed in an energetic, late stage of activity. Although a Late Noachian age for the fan-deltas' formation is not excluded based on crosscutting relationships and crater counts, this indicates evidence of a Hesperian age with significant implications for exobiology.

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Section: Chronological Relationships With Surrounding Landforms and Gmentioning

confidence: 95%

Section: Interpretation Of the Differences In Morphologymentioning

confidence: 99%

Fluvial Regimes, Morphometry, and Age of Jezero Crater Paleolake Inlet Valleys and Their Exobiological Significance for the 2020 Rover Mission Landing Site

et al. 2020

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“…These observations suggest that the olivine-and carbonate-bearing rock could have physical properties similar to those of some of the mudstones in Gale crater (e.g., finely laminated, fine grained, perhaps crosscut by veins). Based on paleotopographic draping stratigraphic relations, these rocks have been interpreted as consisting of weathered, olivine-bearing tephra (Kremer et al, 2019;Mandon et al, 2020). The draping stratigraphy could also be consistent with interpretations that the material is loessite, duststone (sensu Bridges and Muhs, 2012), or even subaqueous mud.…”

Section: Jezero Crater Deltaic Sedimentmentioning

confidence: 79%

Extraformational sediment recycling on Mars

et al. 2020

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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 show that some sedimentary rocks previously buried to depths of kilometers have been exposed, by erosion, at the surface. Four locations in Gale crater, explored using the National Aeronautics and Space Administration’s Curiosity rover, exhibit sedimentary lithoclasts in sedimentary rock: At Marias Pass, they are mudstone fragments in sandstone derived from strata below an erosional unconformity; at Bimbe, they are pebble-sized sandstone and, possibly, laminated, intraclast-bearing, chemical (calcium sulfate) sediment fragments in conglomerates; at Cooperstown, they are pebble-sized fragments of sandstone within coarse sandstone; at Dingo Gap, they are cobble-sized, stratified sandstone fragments in conglomerate derived from an immediately underlying sandstone. Mars orbiter images show lithified sediment fans at the termini of canyons that incise sedimentary rock in Gale crater; these, too, consist of recycled, extraformational sediment. The recycled sediments in Gale crater are compositionally immature, indicating the dominance of physical weathering processes during the second known cycle. The observations at Marias Pass indicate that sediment eroded and removed from craters such as Gale crater during the Martian Hesperian Period could have been recycled to form new rock elsewhere. Our results permit prediction that lithified deltaic sediments at the Perseverance (landing in 2021) and Rosalind Franklin (landing in 2023) rover field sites could contain extraformational recycled sediment.

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“…If the thermal inertia is high, the surface's temperature responds slowly to heating, like large rocks or competent lava flows. The thermal inertia of the olivine-carbonate lithology has already been reported as relatively low (Rogers et al, 2018) and this was interpreted as being potentially at odds with the idea of the unit being a lava flow (Kremer et al (2019) and Mandon et al (2020)).…”

Section: The Thermal Inertia Problemmentioning

confidence: 98%