Caracterización petrográfica y geoquímica de las Unidades Tres Lagunas y Sabanilla en la Cordillera Real entre los 3.5O S y 5O S.

Abstract

The present work referred to the petrographic and geochemical characterization of the Tres Lagunas and Sabanilla Units belonging to the Loja Division in the Cordillera Real, between the provinces of Loja and Zamora Chinchipe in the south of the country. Tres Lagunas units petrography identifies three types of lithologies; granites, gneisses and schists with mineralogical associations comprising quartz + albite + potassium feldspar + biotite ± muscovite originated from quartz-feldespathic rocks. Several microstructures were registered as a result of the deformation to which these rocks were subjected, among these we have the microcrenulation and development of factories S/C. Regarding the Sabanilla Unit, two lithologies were recognized for gneisses and schists with mineral associations characteristic of igneous rocks such as in the Tres Lagunas Unit and also of pelitic origin (quartz + plagioclase + alkali feldspar + biotite ± moscovite ± cordierite ± andalusite ± staurolite ± garnet) where most of the samples with this mineralogical association reach amphibolite facies or even greater. Geochemically both Units exhibit aluminum saturation indexes greater than 1, identifying themselves as S-type granites. They present high contents in LREE with respect to HREE, reflected in the relationships of (La / Yb) CN> 1, and when correlated with the crust The upper continental levels show the same concentrations of trace elements confirming the existence of cortical material in their composition. Through the relationships of major oxides and trace elements, the composition and provenience of the rocks were determined for both units associated with a rift zone.