Mounds in Oxia Planum: The Burial and Exhumation of the ExoMars Rover Landing Site

Abstract

Oxia Planum is the planned landing site of ESA's ExoMars "Rosalind Franklin" rover (Vago et al., 2017). This low-relief plain is situated on the hemispheric dichotomy boundary in the transitional terrain (classified as HNCc1-Early Hesperian to Late Noachian in Tanaka et al. (2005)) between the ancient, rugged highlands of Arabia Terra and the younger, smoother lowlands of Chryse Planitia. Rosalind Franklin will investigate the surface and subsurface geologic and geochemical environments of Oxia Planum, with a primary objective to search for evidence of extinct life through the identification of potential habitable paleoenvironments and biosignatures (Vago et al., 2017). Oxia Planum contains a diversity of Noachian-aged geologic features and geochemical characteristics which make it a suitable candidate for astrobiological exploration, including extensive Fe/Mg-rich clay-bearing plains indicative of widespread aqueous alteration (e.g.,

Spectral Analysis of Clay-bearing Outcrops in Northern Xanthe Terra, Mars: Comparison with Oxia Planum, the Landing Site for the ExoMars Rover Mission

“…Dark patches are also found on the neighboring areas and are interpreted as remnants of a formerly continuous layer of volcanic tephra or ash emplaced through eruptions in nearby Lederberg crater (Brož & Hauber 2013). Moreover, the presence of inverted landforms, isolated mesas and buttes (mounds), and degraded craters in northern Xanthe Terra (Adler et al 2022;Frueh et al 2022), notably in Magong crater (Figure 10(a)), testifies to the significant erosion occurring in the entire region, similar to what happened in Oxia Planum (e.g., Favaro et al 2021;McNeil et al 2021McNeil et al , 2022Quantin-Nataf et al 2021).…”

“…Oxia Planum harbors the remains of a fan delta and several patches of dark rough deposits partly capping the basin, namely Raetia Palus and Dark Resistant Unit, respectively (Ivanov et al 2020;Quantin-Nataf et al 2021;Brossier et al 2022a). Many mesas and buttes are widespread throughout the region and elsewhere in southern Chryse Planitia (McNeil et al 2021(McNeil et al , 2022, with diverse size and shape as in northern Xanthe Terra (Adler et al 2022;Frueh et al 2022). Thus, as mentioned above, both regions present a very similar geologic context at regional scale.…”

Repeated and Long‐Lasting Fault Activation on Amazonian Mars as Demonstrated by Tectonically Induced Landslides

“…Stresses related to the dichotomy boundary and the isostatic adjustment of the highlands and lowlands were proposed by Ruj and Kawai (2021) for the formation of Amazonian wrinkle ridges in Amenthes Planum, and Watters (1993) proposed that dichotomy‐related stresses produced dichotomy parallel shortening structures. Widespread exhumation of Noachian terrain has occurred across the dichotomy in western Arabia Terra (McNeil et al., 2022; Quantin‐Nataf et al., 2021), which may have contributed to Hesperian dichotomy‐related stresses. Although, the shortening structure in the study area is oriented oblique to the dichotomy boundary (NE‐SW, Figure 1), it could have been re‐activated by dichotomy‐related stresses.…”

The high-resolution map of Oxia Planum, Mars; the landing site of the ExoMars Rosalind Franklin rover mission

“…These units constitute isolated hills (hMm) that make up the lithologically distinct top parts of geomorphological identifiable mounds. These landforms are thought to be remnants of a ∼100 m thick layer (McNeil et al, 2022). However, the deposition and erosion mechanisms for the unit, which may be significant for the preservation of biosignatures, are unresolved.…”