 Therefore, most of the rocks were reworked and highly metamorphosed with changes in minerals and texture.Due to the sparse exposure of pre-Neoarchean rocks, only the tectonic settings of the rocks generated from 2.7 to 1.85 billion years ago (during the Neoarchean and Paleoproterozoic Era) are thought to be understood.These settings include a Large Igneous Province event, mantle plume activity, continental collisions, rifting and subductions of plates.