Chronological zoning of plutonism in the northern Patagonian Andes between 40°00'? and 42°00'? South: the migration of intrusive cycles

Abstract

?Chronological zoning of plutonism in the northern Patagonian Andes between 40°00? and 42°00? South: the migration of intrusive cycles?. Many K/Ar and Rb/Sr determinations on mineral separates of granitoids from the Patagonian Cordillera between 40°00? and 42°00? South, support a certain chronological zonation and apply for a migration E to W of the intrusive loci in geological times. This zonation is based upon the evidence of a marginal eastern belt of granitic rocks considered of Precambrian-Paleozoic ?uncertain age?, an intermediate area of Cretaceous granitoids and one, even inward belt of Tertiary age. The progressive lower age of magmatic episodes toward the W, is also reassured by stratigraphical data and eliminate the possibility of a ?rejuvenation? of the ages. On the chilean slope a similar reverse zonation has been proposed. The author proposes a scheme with a stable position of intrusive loci of Cretaceous and Tertiary age.