Rivers and Lakes in Western Arabia Terra: The Fluvial Catchment of the ExoMars 2022 Rover Landing Site

Peter Fawdon,John Bridges,Joel Davis,Matthew Balme,Cathey Quantin‐Nataf,Sanjeev Gupta

doi:10.1029/2021je007045

Abstract

AbstractOxia Planum, the landing site for the ExoMars rover mission, is a shallow basin on the southern margin of Chryse Planitia that hosts remnants of fan‐shaped sedimentary deposits associated with the ancient channel system Coogoon Vallis. This indicates runoff from a catchment in Arabia Terra has transported sediment into the landing site. To explore this fluvial system we created a model catchment for Oxia Planum and, using 6 m/pixel ConTeXt camera orbital remote sensing image data, we digitized the fluvial and lacustrine landforms in Western Arabia Terra in and around this catchment. We find: (a) The catchment has a minimum area of ∼2.1 × 105 km2 and has been episodically deformed by tectonic activity; (b) There were at least two phases of fluvial activity. The first created a mature landscape associated with Coogoon Vallis, which may have deposited alluvial or deltaic deposits in the Oxia Basin. After a substantial hiatus, a second phase of activity incised U‐section channels into the pre‐existing landscape and channel systems; and (c) Evidence for numerous possible paleolake deposits within the catchment. These are not well connected to the fluvial system and were probably sustained by groundwater activity contemporaneous with both phases of fluvial activity. This groundwater might have modified the mineralogy of Oxia Planum. Oxia Planum probably experienced an alluvial or distal deltaic/lacustrine depositional environment during the mid Noachian, which was later overprinted by a younger phase of fluvial activity.

Highlights

Oxia Planum is the landing site for the European Space Agency and Roscomos ExoMars2022 mission (Vago et al, 2018)
We make no interpretation about the genesis of these fans as alluvial or deltas and are hereafter referred to as 'sediment fans'. These sediment fan remnants appear to be associated with Coogoon Vallis and, the exact relationship is obscured by Kilkhampton crater (IAU, 2019; Figure 1c), the channel systems that enter the Oxia Basin from the east, along with a group of unnamed channels from the south, are likely to have supplied water and sediment into the basin from Arabia Terra
The hydrological flow accumulation calculations show a total model catchment area of 2.1×105 km2 (Figure 2). This represents the total upslope area from which water would flow over the contemporary topography though the Oxia Basin and northwards to Chryse Planitia

Summary

Introduction

Oxia Planum is the landing site for the European Space Agency and Roscomos ExoMars2022 mission (Vago et al, 2018). The rover will use the Pasteur instrument suite to search for physical and chemical biosignatures on samples collected from up to 2 m below the surface (Vago et al, 2017) To meet this ambitious mission goal, it is crucial to understand the geological context of geochemical processes that have occurred in Oxia Planum. We make no interpretation about the genesis of these fans as alluvial or deltas and are hereafter referred to as 'sediment fans' These sediment fan remnants appear to be associated with Coogoon Vallis and, the exact relationship is obscured by Kilkhampton crater (IAU, 2019; Figure 1c), the channel systems that enter the Oxia Basin from the east, along with a group of unnamed channels from the south, are likely to have supplied water and sediment into the basin from Arabia Terra

Objectives

Results

Discussion

Conclusion