Proterozoic basement, paleozoic tectonics of NW South America, and implications for paleocontinental reconstruction of the Americas

Abstract

This paper summarizes geological data from the basement massifs of the northern Andes, which constrains their evolution since Late Proterozoic time. Regional associations, age, and tracer isotopic data suggest that two orogenic episodes—Orinoquiense-Grenvillian (~1.0 Ga) and Quetame-Caparonensis (~0.47 Ga)—consolidated the basement of the northern Andes, here referred to as the Chicamocha terrane. The Paleozoic paleogeography has been refined by establishing connections between provincial fauna. Faunal constraints indicate a Gondwanan affinity in the Cambro-Ordovician and an Appalachian character for the Siluro-Devonian assemblages. In a broader context, the proto Andean Grenvillian-Orinoquiense (~1.0 Ga) and Quetame-Caparonensis-Famatinian (~0.5–0.43 Ga) orogens may be traced from the Andes of Venezuela down to Argentina. A fragment of the Chicamocha terrane and its Cambro-Ordovician cover was “transferred” to southern Mexico in Late Paleozoic time. Permian magmatic belts running along active margins in Mexico and northern South America place a time limit for this connection at the onset of the assemblage of Pangea.