The Coastal Batholith of Peru

Abstract

The 1600 km long Coastal Batholith of Peru is emplaced, in the main, within an ‘ensialic’ marginal basin, of lower Cretaceous age, made up of volcaniclastics, pillow lavas, sills and gabbros. Major and trace element analysis indicate much of the variation, from quartz diorite to granite sensu stricto, is the result of fractionation in place, though some may have occurred on ascent or in intermediate magma chambers. The fact that the batholith crosses from the marginal basin in the north, with no underlying old crustal component, on to old Precambrian thick crust in southern Peru, without any major change in chemistry or petrology indicates that crustal contamination, if present, is of minor importance in the genesis of the batholith rocks.