Earth's outer shell ballooned during massive growth spurt 3 billion years ago

"The researchers found evidence for this growth spurt hiding in ancient zircon crystals in stream sediments in Greenland." Those eroded stream sediments from earlier crust must contain other minerals (clay minerals with potassium?) whose earlier geological age could be determined to see if the sources of those minerals were the same, along with the environmental conditions at the time they were formed.