Geology of Peru
The oldest rocks in Peru date to the Precambrian and are more than two billion years old. Along the southern coast, granulite and charnockite shows reworking by an ancient orogeny mountain-building event. Situated close to the Peru-Chile Trench, these rocks have anomalously high strontium isotope ratios, which suggest recent calc-alkaline volcanism. In the Eastern Cordillera of Peru, Precambrian magmatism in the Huanaco region produced ultramafic, mafic and felsic rocks, including serpentinite, meta-diorite, meta-gabbro, meta-tonalite and diorite and granite that intruded after the first phase of orogenic tectonic activity. The Grenville orogeny had a major impact in Peru. The basement of the Central Andean orogeny includes the rocks of the Arequipa Massif, which reach granulite grade on the sequence of metamorphic facies and formed around 1.9 billion years ago. Zircon grains in these rocks match those in Labrador, Greenland and Scotland, indicating that much of western South America originated as a promontory of the proto-North American continent Laurentia. ==Earthquakes==