Geologic map of the Coprates Quadrangle of Mars

The Coprates quadrangle lies to the east of the Tharsis volcanic complex and the Noctis Labyrinthus tectonic complex. To the north are the plains of Lunae Planum, to the east the vast patches of chaotic terrain and the large sinuous channels that trend northward into Chryse Planitia. On the southwest is the Thaumasia Fossae region of tectonically deformed cratered terrain, to the southeast, the Argyre Basin, the best preserved of the ancient martian impact basins. The geology of the Corpates quadrangle is dominated by the Valles Marineris chasma system, which stretches in an east-southeast direction for about 2,500 km across the quadrangle. Its maximum width is about 600 km from the north rim of Ophir Chasma to the south rim of Melas Chasma. The terminus of Valles Marineris at the eastern edge of the map is about 500 km wide in the north-south direction. Individual segments of the chasma system are 100 to 150 km wide and 2 to 4 km deep.