Oxia Planum, landing site for 2020 P.Thollot1, C. Quantin1, J. Carter2, D. Loizeau1 and B. Bultel1

Mars 2020 First Landing Site Workshop (1) Laboratoire de Géologie de Lyon, France May 14–16, 2014, Crystal City, VA (2) IAS, France

NOTE ADDED BY JPL WEBMASTER: This content has not been approved or adopted by, NASA, JPL, or the California Institute of Technology. This document is being made available for information purposes only, and any views and opinions expressed herein do not necessarily state or reflect those of NASA, JPL, or the California Institute of Technology. Oxia Planum location

Oxia Chryse Planum

Meridiani

Valles Marineris Oxia Planum, wide clay-bearing plain

Mawrth Vallis

Ares Vallis Oxia Planum, wide clay-bearing unit

OMEGA+CRISM MSP-Mapping criteria : 2.3 microns band , Mg/Fe Phyllosilicates Geological context: age

Crater counts on Oxia-Mawrth region - Oxia-Mawrth Region is 4 Gy (+/- 200 My) old - Intense crater obliteration from 4 Ga to 3.6 Ga - Moderate but continuous erosion since 3.6 Ga Geological context: morphology

Basement unit Ridged unit

Fan deposit

Coogoon Basement outflow channel unit

Channels Geological context: hydrated minerals

CRISM MSP Fe/Mg-Phyllo Red: Fe-bearing phyllosilicates 100m/pix unit Outline of 25x20 km Landing Ellipse

Fe/Mg-Phyllo unit

Fe/Mg-Phyllo Mawrth-Vallis- unit like stratigraphy Geological context: evidence for volcanism

Large Caldeira detected further north in (Michalski and Bleacher, 2013) Geological context: Fan shaped deposit in paleo-basin at the mouth of Coogoon Valles Runoff channel ? Paleo-basin outline ? Fan deposit

Bedrock unit

Coogoon Vallis N Capping unit outlet

Bedrock unit Runoff Ejecta channel ? blanket

Coogoon Vallis S outlet Geological context: Fan shaped deposit in paleo-basin at the mouth of Coogoon Valles Runoff channel ? Paleo-basin outline ? Fan deposit

Bedrock unit

Coogoon Vallis N Capping unit outlet

Bedrock unit Runoff Ejecta channel ? blanket

Coogoon Vallis S outlet

Fan shaped deposit

1 km Zoom on divergent Finger-like terminations Flat surface and No obvious channels : subaquous delta fans ? Geological context: Fe/Mg-phyllosilicates, hydrated silica/kaolinite

CRISM MSP Red: Fe-bearing minerals 100m/pix Yellow: Fe/Mg-phyllosilicates Low S/N Blue: Si-OH/Al-OH

Fan deposit

CRISM FRT 20m/pix high S/N Possible traverse routes from ellipse center

Red: Fe-bearing phyllosilicates East route: distal fan deposits stratigraphy

Bedrock unit

Fan deposits

Capping unit: lava flows

Bedrock unit

25x20 km Landing Ellipse route: proximal fan Possible long deposits and bedrock term target: stratigraphies bright layered deposits (‘Mawrth-like’) Land on Fe/Mg-Phyllo bearing unit

Red: Fe-bearing phyllosilicates Land on Fe/Mg-Phyllo bearing unit

Red: Fe-bearing phyllosilicates

Center of Landing Ellipse Fan deposits

Most recent exposures of phyllo- bearing outcrops

+1 km +2.5 km

Possible traverse routes Dark capping unit, retreating southward Land on Fe/Mg-Phyllo bearing unit: morphology

NB: No HiRISE on ellipse center: shown here is a sample of the same unit ~4 km to the East

Polygonally fractured surface: probable dessication cracks: Depositional and/or diagenetic

Smooth material: probable erosion of fractured unit and/or removed capping unit > favorable for roving Capping unit: prob. lava flows currently eroding away: young exposure age

Dark capping unit, retreating Recent exposure of Fe/Mg-phyllo-bearing unit Red: Fe-bearing phyllosilicates

Fan deposits +5/+8 km

+9 km Fan deposits stratigraphy exposed in craters

South route: Exposed stratigraphy of proximal fan deposits Red: Fe-bearing phyllosilicates

+10 km Basement unit: Fe/Mg-phyllo bearing

Fan deposits South route

+10 km

Fe/Mg-Phyllo basement unit Red: Fe-bearing phyllosilicates

+10 km Basement unit: Fe/Mg-phyllo bearing

South route

+12 km Fe/Mg-Phyllo basement unit Fe/Mg-phyllo signatures Red: Fe-bearing phyllosilicates

+15.5 km Late lava flow, associated aqueous alteration, stratigraphic relationship w/ Fe/Mg-phyllo unit South route

Si-OH signatures Coogoon Vallis lava flow (= capping unit ?)

+15.5 km

Fe/Mg-phyllo basement unit Red: Fe-bearing phyllosilicates

+20 km

+17 km

+24 km +21 km Possible long term target: bright layered deposits with similar stratigraphy as Mawrth Vallis

East route

South Coogoon Vallis lava route flow (= capping unit ?)

Mawrth Vallis – like +17 km Layered deposits

Fe/Mg-phyllo basement unit

Si-OH signatures

+21 km Current datasets coverage

HRSC CTX HiRISE CRISM Target requests

HiRISE CRISM

Lon. , Lat. Lon. , Lat.

-23.98,17.80 -23.75,17.71 -24.00,17.97 -23.94,17.88 -24.08,17.84 -23.95,18.01 -23.91,18.04 -23.80,17.88 -24.01,17.66 -23.81,17.69 -23.72,17.70 Oxia Planum Essentials

• Surface aqueous alteration of basement unit: Fe/Mg-Phyllosilicates

• Noachian age: ~4 Ga; units overlain by Ridged plains

• Noachian fan-shaped sedimentary deposits in paleobasin: delta ? fossil river channels in basement unit

• Igneous units, Noachian and/or Hesperian (lava flows, caldeiras)

• Ancient capping unit: altered basement and deposits shielded from later alteration

• Recent erosion of capping unit exposing preserved older units

• Prob. Mawrth-Vallis-like stratigraphy on basement, as close as 4 km from ellipse

• Exomars candidate landing site (potential exploration synergy)