Fluvial Deposits in Margaritifer Basin Kevin K. Williams and John A. Grant Center for Earth and Planetary Studies, Smithsonian Institution Corey M. Fortezzo Department of Geology, Northern Arizona University

Fluvial Deposits in Margaritifer Basin Noachian through Amazonian terrains complex and interesting fluvial history interesting minerals other water/ice related features nearby volcano-water interactions veins of gold at this point, it looks ‘safe’

Location MC-19 is east of Valles Marineris Argye Margaritifer basin

MB1: 12º 40.97’ S / 338º 06.34’ E MB2: 11º 41.83’ S / 337º 16.95’ E MB1 MB2

Overview of geologic setting Margaritifer basin is located at the confluence plain of the UHLM, Samara, and Parana- Loire valley systems These three valley systems drain a large area of Mars, and it appears that water ponded in Margaritifer basin. -> possibility of sampling material from a broad area of the martian highlands Widespread fluvial activity extended from the Noachian into the mid- to late-Hesperian Latest activity in MB extended into the Amazonian

Nplh: Noachian hilly plains Npl1: Noachian plateau sequence Hch: Hesperian channel Large scale geologic map 1:500,000 geologic map More detailed unit boundaries Younger units in Margaritifer basin Nearby, chaos, collapse, volcanics, Noachian remnants * *

1:500,000 geologic map More detailed unit boundaries Younger units in Margaritifer basin Nearby, chaos, collapse, volcanics, Noachian remnants * *

Edge of channel in MB MOC image NASA/JPL/MSSS MOC image E NASA/JPL/MSSS Layering in plains of Margaritifer basin Amazonian plains

MOC image NASA/JPL/MSSS MOC image E NASA/JPL/MSSS Layering in plains of Margaritifer basin High res. imaging in landing circles will likely reveal layering there

THEMIS VIS views

Within Margaritifer basin, fluvial activity took place from the Noachian through the Amazonian Geomorphic evidence suggests that water ponded in MB and infiltrated into the subsurface, possibly getting re-mobilized during collapse and outwash through Ares Valles The basin plain is mainly smooth with higher remnants and areas where the layers of deposited material are exposed where they have been etched into Nearby activity also includes chaotic terrain, collapse, and a volcanic feature that may have interacted with water/ice Past through recent/present areas of habitable potential Prolonged accumulation of water Access to spatially and temporally diverse material Increase in geologic features and potential for habitability

Elevation Landing ellipses are lower than -2 km MB1: m MB2: m

Slopes calculated from MOLA >15º 5º < x < 15º 3º < x < 5º ≤ 3º Requirement: <3º over 2-5 km

Very low within landing ellipses Rock abundance ~10% (need more info) Surface roughness

TES dust coverage Requirement: low Essentially 0 at landing sites TES thermal inertia Requirement: > 100 J m -2 s -0.5 MB1: avg. = 315 MB2: avg. =

TES hematite (on scale) TES carbonates MB1: MB2: MB1: low but.025 to NE MB2: ~ 0.02

TES sulfates MB1: MB2:

Engineering summary Elevation: very low. lots of time to slow down Slopes: generally gentle, but more info will be helpful Surface roughness: landing ellipses appear to meet requirements and allow access to nearby rougher ROIs Thermal inertia: High thermal inertia Minerals: Relatively high levels of hematite, carbonates, and sulfates Albedo: < 0.25

Summary Margaritifer basin has a complex and long-lived fluvial history that involves ponding of water This area provides access to materials from diverse areas of the martian highlands These materials also span fluvial activity from the Noachian though the Amazonian Layers from episodes of activity likely exist in landing area Nearby chaos, collapse, and volcanics increase scientific interest and potential for habitability At this stage, both circles appear safe