Earthlike Plate Tectonics on Mars

The newer evidence comes from a high-resolution magnetic field map. It is the first of its kind. It covers Mars’ entire surface, and is based on four years of data taken in constant orbit. This new map shows ‘striping’ of magnetic fields in different regions of Mars. Each stripe represents a magnetic field pointed in either a positive or negative direction, while the alternating stripes indicate that the magnetic field has flipped from one stripe to another.

Similar stripes can be found in the Earth’s crustal magnetic field. They form whenever two plates are being pushed apart by molten rock coming up from the mantle. The plate becomes magnetized in the direction of the Earth's strong global magnetic field as it spreads and cools. Because, Earth's global field changes direction a few times every million years, on average, flows that cool in different periods will be magnetized in a different directions. As the crust is pushed out and away from the ridge, stripes of alternating magnetic fields aligned with the ridge axis develop.

This striping imprint on Mars indicates that it had regions where new crust came up from the mantle and spread out across the surface. Whenever crust is coming up, there must be crust plunging down--the mechanism for plate tectonics.

Plate tectonics can explain several Martian features: the magnetic pattern itself; the Tharsis volcanoes, which lie along a straight line, and could have formed from the motion of a crustal plate over a fixed "hotspot" in the mantle below; and the Valles Marineris, a large canyon six times as long as the Grand Canyon and eight times as deep, which is oriented just as one would expect from plate motions implied by the magnetic map, and looks just like a rift formed on Earth by a plate being pulled apart.