NASA’s Curiosity rover has provided evidence of Mars’ primitive continental crust using ChemCam laser instrument, which showed that the rocks were surprisingly similar to Earth’s granitic continental crust rocks.
Roger Wiens of Los Alamos National Laboratory, lead scientist on the ChemCam instrument said that they saw some beautiful rocks with large, bright crystals, quite unexpected on Mars. As a general rule, light-colored crystals have lower density, and are abundant in igneous rocks that make up the Earth’s continents.
This is the first discovery of a potential “continental crust” on Mars.
French and US scientists observed images and chemical results of 22 of these rock fragments. They determined that these pale rocks were rich in feldspar, possibly with some quartz, and were unexpectedly similar to Earth’s granitic continental crust.
According to the paper’s first author, Violaine Sautter, these primitive Martian crustal components bear a strong resemblance to a terrestrial rock type known to geologists as TTG (Tonalite-Trondhjemite-Granodiorite), rocks that predominated in the terrestrial continental crust in the Archean era (more than 2.5 billion years ago).
Gale crater, excavated about 3.6 billion years ago into rocks of greater age, provided a window into the Red Planet’s primitive crust. The crater walls provided a natural geological cut-away view 1-2 miles down into the crust. Access to some of these rocks, strewn along the rover’s path, provided critical information that could not be observed by other means, such as by orbiting satellites.
The results are published in Nature Geoscience.