From Lake to River: Documenting an Environmental Transition Across the Jura/Knockfarril Hill Members Boundary in the Glen Torridon Region of Gale Crater (Mars)

Abstract

 Sedimentary facies observed by Curiosity suggest lacustrine and fluvial environments preserved in the Glen Torridon stratigraphy. A paleoenvironmental transition is observed across the Jura/Knockfarril Hill members boundary, suggesting onset of fluvial conditions. This transition is progressive, and consistent within both the sedimentary and geochemical signals in the Glen Torridon region.

Orbital and In‐Situ Investigation of Periodic Bedrock Ridges in Glen Torridon, Gale Crater, Mars

“…Given that evidence strongly supports an erosional, rather than constructional origin for the ridges, this study concludes no connection between the formation of the ridges and the primary depositional process by or environment in which the Glen Torridon rocks formed. This study's interpretation of the ridges as post‐depositional erosional features formed after the deposition of the units of the Gale mound is consistent with the ground‐based lacustrine and fluvial interpretation for the rocks of Jura, Knockfarril Hill, Glasgow members (Carvaaca et al., 2021 ; Edgar et al., 2020 ; Fedo et al., 2019 ).…”

“…The Murray formation and overlying “Carolyn Shoemaker” formation have been split into different members defined by variations in lithology, facies, and diagenetic textures (Carvaaca et al., 2021 ; Fedo et al., 2019 ; Figure 2 ). Curiosity's major exploration targets within the Murray formation included the strata of “Vera Rubin” ridge (VRR), an indurated, erosion‐resistant ridge exhibiting distinct spectral absorptions attributed to crystalline hematite observed in orbital spectroscopic data (Fraeman et al., 2013 ), and an E‐W elongated trough immediately to the south of VRR called Glen Torridon, in which Fe‐smectite clay‐bearing Murray bedrock crops out (Bennett et al., 2019 ; Fox et al., 2021 ).…”

“…The rover's exploration of Glen Torridon began on sol 2302, and concluded around sol 3080 (Fox et al., 2021 ). In‐situ exploration by the Curiosity rover revealed that the northern Glen Torridon area is comprised of finely laminated mudstones of the Jura member (Carvaaca et al., 2021 ), and covered throughout by a regolith layer composed of locally eroding pebble‐ to cobble‐sized clasts (Christian et al., 2022 ; Khan et al., 2021 ). There is some uncertainty about the extension of the Pettegrove Point‐Jura contact east of the rover's traverse, so it is possible that Pettegrove Point may also be exposed within parts of Glen Torridon.…”

“…Since the Jura member crops out in both VRR and Glen Torridon, herein it is referred to as either the GT Jura or VRR Jura. Erosion‐resistant, cross‐bedded sandstones of the “Knockfarril Hill” member of the Carolyn Shoemaker formation overlie the Jura member throughout Glen Torridon, locally eroding into isolated mesas throughout Glen Torridon that transition into more continuous exposures to the south and up stratigraphic section (Carvaaca et al., 2021 ; Fedo et al., 2019 ). The Knockfarril Hill member is overlain by the “Glasgow” member of the Carolyn Shoemaker formation (Carvaaca et al., 2021 ; Fedo et al., 2021 ) (Figure 2 ).…”

Sedimentological and Geochemical Perspectives on a Marginal Lake Environment Recorded in the Hartmann's Valley and Karasburg Members of the Murray Formation, Gale Crater, Mars

“…The Murray formation is subdivided into seven stratigraphic members based primarily on lithology (Figure 1c). Of the seven members, thorough facies analyses have been done throughout the Pahrump Hills (Grotzinger et al., 2015; Stack et al., 2019), Blunts Point, Pettegrove Point, and Jura members (Caravaca et al., 2022; Edgar et al., 2020), while more localized studies have been done throughout the Sutton Island member (Rapin et al., 2019; Stein et al., 2018). Much of the Murray formation consists of meters thick intervals of planar laminated mudstone that are interpreted to represent deposition in low‐energy lacustrine basin environments (e.g., Edgar et al., 2020; Stack et al., 2019).…”