20-EPN2-121: Constraining the movement of groundwater and fluid expulsion within playa environments on Mars
November 14, 2021

20-EPN2-121: Constraining the movement of groundwater and fluid expulsion within playa environments on Mars

Visit by Gene Schmidt, Università degli Studi Roma Tre (Italy) and Erica Luzzi, Jacobs University (Germany) to TA1.5 Makgadikgadi Salt Pans (Botswana).
Dates of visit: 20-27 October 2021

Across the surface of Mars there is evidence of past lacustrine and evaporitic environments found within basins and craters, where often layered sedimentary deposits and hydrated minerals are observed. However, the intensity, duration and precise phases of water cycle activity during this period remain unresolved. Although several geological processes and locations on Earth have been previously proposed as examples to describe these deposits on Mars, we lack a strong visualisation of what water activity might have looked like during evaportic stages within basins and craters. The Makgadikgadi Salt Pans of Botswana, where once the Makgadikgadi Lake existed, is a present evaporitic environment rich in hydrated minerals and water activity. It is a depression located at the southwestern end of a northeast-southwest set of graben. Faults have been previously proposed to have been pathways for groundwater to enter basins and craters on Mars, which then contributed to both the deposition and alteration of the sedimentary deposits. Thus, imaging the subsurface of a similar environment on Earth can help us to better understand how water processes on Mars might have continued as the Martian global climate became drier.

By using the already established locations of the faults to the north of the pans, we used remote sensing techniques to trace the best location of the faults underneath the pans (Figures 1 and 2). We then used electrical resistivity surveys to image 70 – 150 m of the pans’ subsurface where the faults were deemed most likely to occur. This work allows us to better understand the possibilities of what the underlying lithology of rocks within filled basins and craters might look like. Furthermore, it demonstrates the scientific importance of future missions to employ subsurface imaging techniques on Mars.

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