Chunk scanning is a mechanic used in the process of resource extraction. Scanning a chunk for resources is required to use a Oil Pump or Geo Miner. Scanning is performed using a GPS Geo Scanner or Portable Geo Scanner.
Placing a GPS Geo Scanner in the GPS network's range and right clicking on it allows you to scan the chunk it is in. This action requires at least 600 Complexity in your GPS Network.
Right clicking on a GPS Geo Scanner again opens a menu with all the resources that you are able to extract from the chunk.