Reconstructing basaltic sediment transport on Mars using terrestrial analogues
National Aeronautics and Space Administration Solar System Workings Program
Non PSI Personnel: Marisa Palucis (Co-Investigator, Dartmouth College), Robert Craddock (Co-Investigator, Smithsonian Institution)
Project Description
The martian geologic record provides compelling evidence for an early climate that supported liquid water on or near the surface, yet the environmental conditions during this period remain uncertain. Climate models tend to support a dominantly cold, and thus icy, climate with mean annual temperatures (MAT) below freezing, while the geomorphological record generally sup-ports warm and wet conditions, with a MAT > 273 K and precipitation-derived surface runoff. Estimates of the paleodischarge that formed these fluvial features provide insights into the past hydrologic and climatic environment, thus offering methods to reconcile the apparent contrasting conclusions between the geologic record and climate models.
Most studies of martian fluvial features utilize orbital data, which cannot use grain size or shape. The observation of stream- transported gravels by rovers offers new methods into recon-structing past fluvial conditions. Reconstructing the transport history of these pebbles pro-vides insights into the prevailing climate at the time of transport and deposition. These reconstructions are hindered, however, by limited data and theory concerning the transport of basaltic sediment. We propose a study using both laboratory experiments and field campaigns at Mars-analogue environments to advance the state of knowledge regarding basaltic grain transport and breakdown, thus providing key insights into deciphering the past fluvial conditions on Mars. We aim to address the question is the identification of rounded basalt pebbles conclusive evidence sustained fluvial transport on Mars?
We will conduct field campaigns in two settings with dominantly basaltic lithology in contrasting climatic regimes: warm Hawaii and cool Iceland. We will collect and document quantitative data on grain size and shape. We will use flume and rotating drum experiments to determine the effects of fluvial and debris flow transport on grain shape. Finally, we will develop new relationships for assessing transport history from grain size, and apply these relationships to Mars.
The proposed work will advance the state of knowledge by improving relationships for characterizing transport history from transported basaltic grains. The derived relationships will be crucial in interpreting data from the Curiosity rover, as well as the upcoming Perseverance and Rosalind Franklin rovers, both of which will land in fluvial environments.
