[1] The rocks of the complex metamorphosed during the Early Paleozoic era but the original protoliths formed in the Proterozoic eon.
[1][3] At their peak conditions of metamorphism rocks reached temperatures and pressures of 700 C and 7 kbar.
[3] The timing of the metamorphism matches the age of the Famatinian orogeny in the Argentine Northwest.
[3] Rocks of the Belén Metamorphic Complex were involved in one or more orogenies in the Early Paleozoic.
[3] Rocks of the complex include foliatied amphibolite, orthogneiss, serpentinite and lesser amounts of quartz-rich mica schist.