How Did an Ancient Climate on Mars Trap Sulfates?
The Curiosity rover and the Franco-American ChemCam1 instrument have mapped a thick formation of sulfate nodules, enabling an international team—including CNRS researchers—to reveal a succession of wet and dry climates on Mars dating back more than 3.5 billion years. This climate evolution is far from a monotonous aridification and resembles Earth’s semi-arid regions.
On a 6-kilometer-high sedimentary massif, the Curiosity rover is traversing layers enriched with sulfate salts. Using data from the Franco-American ChemCam1 instrument, an international team led by William Rapin has shown that these sulfates formed within sediments 200 meters thick during climate fluctuations more than 3.5 billion years ago. These results, published in the journal JGRP, indicate that the salts crystallized, forming nodules, each time the water table evaporated.
ChemCam has enabled the high-resolution mapping of fine sedimentary structures exposed up to 1.5 km around the rover, revealing traces of ancient dune fields interspersed with ephemeral rivers. The instrument also analyzes the chemical composition at each of the rover’s stops, revealing a large population of nodules rich in calcium and magnesium sulfates. Mapping of these nodules indicates they formed through evaporation when the water table was close to the surface.
Read more on the CNRS Terre & Univers website.
Contact GET: Gwenael Caravaca
