Drainage evolution in the Margaritifer Sinus region, Mars

Abstract

Margaritifer Sinus, Mars, records a complex history of water transport, storage, and release extending from the late Noachian into at least the mid‐Hesperian. Collection, transport, and discharge of water were accomplished by systems of differing character flanking opposite sides of the Chryse Trough. Drainage on the western side of the trough was via the segmented Uzboi‐Ladon‐Margaritifer mesoscale outflow system that heads in Argyre Basin and incises and fills as it crosses ancient multiringed impact basins. By contrast, Samara and Parana‐Loire Valles, two of the largest and best integrated valley systems on Mars, dominated drainage on the eastern trough flank. Valley morphometry suggests formation was due to precipitation‐recharged groundwater sapping. All systems discharged into Margaritifer Basin, located along the Chryse Trough axis, and caused ponding that persisted into the early Hesperian. The Uzboi‐Ladon‐Margaritifer system dominated discharge that was coincident with widespread geomorphic activity on Mars. As channel and valley formation ended, some water in Margaritifer Basin infiltrated the subsurface. Collapse and release of water began shortly thereafter and persisted into mid‐Hesperian times, thereby forming Margaritifer and Iani Chaos and incising Ares Vallis.