162-8 Geologic Mapping of the Samara-Himera and Paraná-Loire Valley Network Systems Near Jones Crater, Mars

Session: Planetary Geologic Mapping Across the Solar System

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Abstract:

We are creating a standardized United States Geological Survey Scientific Investigation Map in Margaritifer Terra along the boundary of northwestern Noachis Terra that encompasses Jones crater and the medial to distal portions of the Samara-Himera and Paraná-Loire valley network systems. The 1:1,000,000 scale map includes four Mars Transverse Mercator quadrangles, -20022, -25022, -20017, and -25017, from 17.5°S-27.5°S between 335°E-345°E. Prior geologic mapping in this region focuses on the drainage evolution and juxtaposition of units in either the eastern or western portions of Margaritifer Terra and northwestern Noachis Terra. This map fills the gap between existing published USGS maps to the east, west, and north to yield a complete regional view of a landscape that records a long history of aqueous processes. The final product will provide the scientific community with a dataset to assess the morphologic and morphometric investigations of valleys and fluvial/alluvial deposits, understand the timing of fluvial activity for climate models, and may inform efforts related to understanding the history of Martian habitability.

We have mapped several geologic units in the map area including craters, central peaks, crater floors, alluvial fans, valleys, and the widespread terra unit and will incorporate compositions derived from CRISM hyperspectral data into mapped unit descriptions. The terra unit has been previously described as smooth to rolling, cratered, and variably dissected surface between degraded impact craters. This unit is interpreted to be a Noachian to Hesperian geomorphic surface resulting from impact cratering, ejecta emplacement, prolonged weathering, and erosion primarily by water and wind. In our map area, the Terra unit may consist of two members, with an upper member that appears to partially mantle a lower member. The mantle is particularly evident on crater floors where it appears dark in THEMIS daytime IR. The mantling portion of the Terra unit is not obviously layered, can appear stippled on the plains, and has variable albedo in CTX. Examples of buried craters and valleys in the map area support this observation. Where the Terra mantle has been stripped away at local (500m to 1km) length scales, there is more relative relief and at least locally higher preserved drainage densities. This stripping provides windows into the underlying terrain and occurs most commonly on valley or crater walls.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-8201

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