Generally large structures like this are related to mining as that is a process that can take large swaths of land and convert it into a few hundred thousand tons of the 'good stuff.'
That being said, the old MX silos could be seen from space but they were pretty clearly revetments and launchers connected by rail lines. Generally large infrastructure often gives away its intent which is why modern despots prefer building everything underground.
One of the comments suggest it was the result of lithium mining..."These sites clearly represent the process of lithium mining and extraction. Sedimentation trenches are dug to extract lithium iron phosphate to create batteries." Sounds reasonable.
That being said, the old MX silos could be seen from space but they were pretty clearly revetments and launchers connected by rail lines. Generally large infrastructure often gives away its intent which is why modern despots prefer building everything underground.