As he travels up the bed of an ancient Martian river, PerseverancePerseverance fell on a strange stone. In the middle of the landscape dotted with dark rocks, Atoko Point is indeed seen as the neznez in the middle of the figure. Atoko Pointthis is the nickname given to this block of light rock located at Mount Washburn.
An igneous rock formed deep in the Martian crust
Thanks to its SuperCam and Mastcam-Z instruments, Perseverance was able to quickly characterize the intruder. The data reveals that the block, which measures 45 x 35 cm, is composed mainly of pyroxènespyroxènes and mostly feldsparsfeldspars, which give it this light color. It could therefore be a anorthositeanorthositea igneous rockigneous rock intrusive (we also speak of plutonic rockplutonic rock), which would have crystallized at depth, perhaps at the level of the crustcrust lower. This is the first time that the rover has discovered this type of rock on the surface of Mars!
Atoko point could therefore help scientists better understand how and when the crust of Mars formed. It remains to be seen how she got there!
A block carried by the river several billion years ago?
There aren’t thirty-six ways to bring it to lifeoutcropoutcrop plutonic rocks. On Mars, we only have to rely on erosion, while on Earth, tectonic movements can also bring up very deep units. It is possible that the rock comes from an ancient magmatic intrusion emplaced in the Jezero crater region. But the very isolated position of the block suggests that it was transported, certainly by the river which fed the crater a long time ago. This stone could therefore come from much further away.
New analyzes may help to learn more about its origin. These results will allow scientists to know if it is worth carrying out a samplingsampling of this rock, with a view to repatriation to Earth.
