Abstract
AbstractThere is abundant evidence for aqueous processes on Noachian terrains across Mars; however, key questions remain about whether these processes continued into the Hesperian as the martian climate became less temperate. One region with an extensive Hesperian sedimentary record is Valles Marineris. We use high‐resolution image and topographic data sets to investigate the fluvial systems in the southwest Melas basin, Valles Marineris, Mars. Fluvial landforms in the basin exist across a wide area, and some are preserved as inverted channels. The stratigraphy of the basin is complex: Fluvial landforms are preserved as planview geomorphic features and are also interbedded with layered deposits in the basin. The fluvial morphologies are consistent with formation by precipitation‐driven runoff. Fluvial processes in the basin were episodic, suggesting multiple wet and dry periods. During dry periods, mantling material accumulated, and significant volumes of sediment were eroded, inverting fluvial channels. During wet periods, inverted channels and mantling material infilling valleys were incised by further fluvial erosion. These trends for episodic fluvial processes are similarly reflected in the central depression of the southwest Melas basin, previously described as a paleolake. Ultimately, fluvial processes in the basin gradually shut down, becoming geographically restricted, and then ceased entirely. We show that branching valley networks are also present on the plateaus above Melas and Ius Chasma, which converge on the heads of tributary canyons. These suggest that precipitation‐driven runoff processes also extended onto the plateaus of Valles Marineris.
Highlights
Much of early Mars was modified by liquid water, evidence of which is preserved in widespread erosional and depositional landforms across its surface
We investigate the Valles Marineris plateaus above the southwest Melas basin (SMB) for evidence of regional fluvial processes and how those may relate to the basin
1.34 channel networks are best preserved adjacent to the paleolake (Quantin et al, 2005; Williams & Weitz, 2014), our observations show that fluvial systems are common across the entire SMB
Summary
Much of early Mars was modified by liquid water, evidence of which is preserved in widespread erosional and depositional landforms across its surface. There are a growing number of reported Hesperian and younger surfaces that have been extensively modified by long-lived aqueous processes (e.g., at Gale Crater; Grotzinger et al, 2015; Rice et al, 2017; Williams et al, 2013), in equatorial regions (e.g., Burr et al, 2010; Grindrod et al, 2012, 2017; Goddard et al, 2014; Le Deit et al, 2010; Mangold et al, 2004, 2008; Salese et al, 2016; Weitz et al, 2008, 2010) These modified surfaces mean that the period that conditions were favorable to liquid water on Mars potentially persisted beyond the Noachian, at least at a local or regional scale.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
