Caracterización de nuevas ocurrencias del basamento de la región Costa de Ecuador: caracterización de afloramientos puntuales en la región Costa de Ecuador.

Abstract

The present project was based on the petrographic and geochemical characterization of outcrops of the Piñon, Orquideas and San Lorenzo basement formations of the Ecuadorian coast. The lithologies analyzed consisted of basalts, gabbros for the Piñon Formation whose mineralogy is plagioclase+pyroxenes in the gabbros, plagioclase+pyroxenes+matrix+olivine in the basalts. Andesites were identified in the Orquideas Formation, with a composition of plagioclase+pyroxenes. For the San Lorenzo Formation, basalts whose composition consists of plagioclase+pyroxenes were observed. Specifically, the sedimentary rocks of the Cayo Formation have a composition of plagioclase + quartz and a clay matrix. For the geochemical treatment of the selected samples, they were divided into three groups, Group 1- Basalts from the Piñon Formation, Group 2- Gabbros from the Piñon Formation and Group 3- Andesites from the Orquideas Formation, so that, geochemically, (in where gabbros and basalts belong), according to the relationships established with the data, Groups 1 and 2 present a flat pattern in REEn (Rare Earth Elements) normalized to Chondrite, similar to that of a plateau oceanic, while Group 3 has an affinity with the influence of a subduction zone, showing similarity to the Naranjal Arch, Río Cala (of the Western Cordillera) and geochemically similar to the Orquideas Formation. Therefore, a priori, the Orquideas Formation is distinguished in the northern zone of the Coastal Region of Ecuador.