Resumen cronoestratigráfico de las rocas ígneas de Costa Rica basado en dataciones radiométricas

Abstract

Based on a recompilation of about 160 K-Ar and U-Th analyses of igneous rocks and their stratigraphic relationships, a synthesis of the magmatic evolution of Costa Rica is presented. The igneous rocks of Jurassic to Oligocene age belong principally to the tholeiitic series. Widespread calc-alkaline volcanism started in the late Miocene and culminated during the Pleistocene in the northern and central part of Costa Rica with the eruption of large volumes of andesitic to rhyolitic ignimbrites and the development of the stratovolcanoes of the Cordillera de Guanacaste and Cordillera Central; some of these volcanoes are still active. Alkaline rocks are subordinate and concentrated on the Caribbean side of Costa Rica. Plutonic intrusions, mainly of late Miocene age, are frequent in the southern part of Costa Rica. The histogram of the available data indicates some periods of more intensive volcanic activity.