Eocene Uplift and Unroofing of the Coastal Batholith near Lima, Central Peru

Undeformed ash-flow tuffs for which a late Eocene age is herein established unconformably overlie eroded granitic rocks of the largely Cretaceous and Paleocene coastal batholith in the lower part of the Pacific slope of the Andes 60 km east of Lima, Peru. These relations (1) indicate rapid uplift of the coastal region, as well as areas farther inland, shortly after Cretaceous-Paleocene plutonism; (2) provide additional evidence for a pulse of Eocene deformation, igneous activity, and uplift contemporaneous with the change in plate movement reflected by the bend in the Hawaii-Emperor trace; (3) suggest that certain of the centered volcano-plutonic complexes of the coastal batholith may have remained active after uplift and erosion of older rocks of the batholith; and (4) demonstrate that rocks of the coastal region and the lower western slopes of the Andes were largely unaffected by middle Miocene tectonism.