Maximum formation timescales martian valley networks
Role: PI
Team:
Funding: NASA Mars Data Analysis Program; NASA Solar System Workings Program
Previous attempts to estimate the age of the valley networks relied on calculations of sediment transport and paleodischarge (the amount of water that flowed through the channels). While these methods gave useful insights, they carried significant uncertainties due to assumptions about martian river behavior and sediment properties. I took a different approach by using impact craters as natural timestamps. By analyzing craters that were formed before and after the valleys, I was able to set maximum constraints on the era of valley formation.
The study focuses on eight different valley systems in northern Noachis Terra and western Terra Sabaea on Mars. I mapped out the valleys and their associated impact craters using high-resolution images from Mars orbiters. By comparing the number and size of craters that either predate or postdate the valleys, I was able to estimate the maximum duration of valley formation. The results suggest that the valleys formed over a period of up to ~100 million years, significantly longer than some previous estimates.
The findings also revealed very low erosion rates during the formation of the valleys, with long-term rates of around ~0.25 meters per million years. These rates are comparable to the modern day Atacama Desert. I suggest that Martian valleys may have been carved by episodic water flow, possibly driven by changes in Mars’ orbital cycles or other climatic factors. Unlike Earth’s rivers, which often flow seasonally, water on Mars may have flowed in rare, intense bursts over long periods of dormancy.
The results has broader implications for understanding the climate history of Mars. They suggests that valley formation on Mars was not a brief event but rather a prolonged process, possibly spanning hundreds of millions of years. The low flow rates and intermittent water activity highlight the challenges of comparing Martian and Earth-like hydrological processes. This research also improves our understanding of the conditions under which liquid water existed on early Mars, which is important for assessing the planet’s potential habitability.