Valles Marineris is the most prominent tectonic feature on Mars, consisting of troughs up to 4000 km (2,500 mi) in length, 200 (120 mi) km in width, and 10 km (6.3 mi) in depth. It’s the largest canyons in the solar system.
The canyons are clearly tectonic in nature. Its a large tectonic “crack” in the Martian crust. Most scientists believe that the canyon was formed as the crust thickened in the Tharsis region to the west, and was subsequently widened by erosion.