GEOLOGY of URUGUAY: a REVIEW. Gómez Rifas,C.G
v 1 GEOLOGY OF URUGUAY: A REVIEW. Gómez Rifas,C.G. Montevideo,Uruguay. 1.Introduction. Uruguay has been a country devoted to breeding cattle and agriculture.Mining has no tradition.The evolution of geological knowledge begun with Dr. Karl Walther who published 53 papers between 1909 and 1948. 2.Preclevonian in Uruguay. 2.1.The Río de la Plata Craton. This unít refers to rocks dated between 1700 to 2300 MY in southern UruguaY,situated on the western side of the Sarandí del Yí-Las Ánimas Suture Zone.This is a my10nitic belt 13000 meters wide. 2.1.1.The Base Complexo 1t i8 integrated by gneiss and migmatites of varied textures,as we11 as deformed granites. Some typical outcrops are:Piedra A1ta,F1orida Department,and near the 1itt1e dam in Costa Azu1,Canelones Department. 2.1.2.Montevideo Formation. ,/~ 2 It is formed by oligoclase gneiss, amp11.ibolites, mieaschist and micaceous quartzites.T11.e gneiss can be visited in Pajas Blancas,Parque Rod6,Carrasco beaches and so on.They are rocks of medium grain size and poor defined sc11.istosity,made by quartz,oligoclase,biotite and muscovite and zoisite as accesory mineraIs. T11.e amphibolites has been classified as ortho and para-amphibolites according to their genesis.The ort11.o- amphibolites have cristalized andesine.The para-amphibolites are generally foliated with medium grain size,integrated by hornblende and andesine with an evident nematoblastic texture.The main accesory mineral is sphene. 2.1.3.San José Formation. lt outcrops at north of San José de Mayo and it is the field rock of Compañia San José Gold Mine,s?uth of Mahoma Granite.
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