Extraformational sediment recycling on Mars

Abstract

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.

Mission Overview and Scientific Contributions from the Mars Science Laboratory Curiosity Rover After Eight Years of Surface Operations

“…2016 ; Edgett et al. 2020 ). The rover traversed along the Stimson’s upper surface while on the Emerson and Naukluft plateaus, and observed isolated outcrops at the Murray buttes.…”

The Role of Seasonal Sediment Transport and Sintering in Shaping Titan's Landscapes: A Hypothesis

“…On Earth, abrasion of mechanically weak evaporitic minerals is known to occur during eolian transport (Jerolmack et al., 2011 ). The source of sand on Mars is unclear (e.g., Tirsch et al., 2011 ) but sedimentary recycling is known to occur (Edgett et al., 2020 ), and many ancient fluvial outcrops could supply pre‐sorted sand‐sized materials (Dickson et al., 2020 ). Furthermore, basaltic grains are mechanically strong (Yu et al., 2018 ) such that Martian winds themselves could have sorted sands over billion‐year timescales.…”

The Evolution of Ancient Fluvial Systems in Memnonia Sulci, Mars: Impact Crater Damming, Aggradation, and a Large Water Body on the Dichotomy?

“…Stratigraphic relationships and crater counts suggest that fluvial activity likely occurred between the mid Noachian and early Hesperian. Our results (a) demonstrate the complex, multi-phase evolution of fluvial systems on ancient Mars (e.g., Edgett et al, 2020) and (b) highlight the importance of regional studies when assessing the nature of the northern lowlands basin on early Mars, which can differ from the global picture.…”