The Coastal batholith of Peru.

Abstract

The 1600 km long Peruvian Coastal batholith, emplaced mainly within an 'ensialic' marginal basin of Lower Cretaceous age, consists of approx 1000 plutons which can be grouped into super-units. In discussing a consistent model for batholith genesis, the following points are discussed: 1) the pluton variation at the present level and its cause, 2) axial variation in the batholith and possible relationship to different levels in the batholith chamber, 3) super-unit coherence over long distances, 4) segmental variations which might bear on the subcrustal structure and 5) crustal environment of the batholith. It becomes apparent that although the coastal batholith was intruded in two, possibly three, very different environments, i.e. the thick Precambrian crustal wedge in the south, the new crust in the central zone and the Palaeozoic crust in the north, it shows no evidence of crustal contamination in either of the two environments so far studied.-J.M.H. Dept. of Geology, Univ. of Liverpool, P.O.B. 147, Liverpool L69 3BX, UK.