Caribbean Tectonics from a Paleomagnetic Perspective

Abstract

The geologic definition of Central America encompasses the area from the Isthmus of Tehuantepec in southern Mexico to the Atrato lowlands in western Colombia (Fig. 1) and was arrived at “more on a geographic basis than on geologic grounds” (Dengo and Boh-nenberger, 1969). The fundamentally different nature of northern and southern Central America has long been recognized (e.g., Vaughan, 1918; Schuchert, 1935; Sapper, 1937). In northern or nuclear Central America, metamorphic and plutonic rocks of Paleozoic and possibly late Precambrian age are overlain by sedimentary strata as old as late Paleozoic (e.g., Weyl, 1980). By contrast, the oldest rocks in southern Central America are of upper Jurassic age (Nicoya Complex; Schmidt-Effing, 1979) and the overlying sedimentary rocks are upper Cretaceous and younger. The boundary between the two areas lies somewhere in Nicaragua. The extensive Tertiary volcanic cover prevents a specific delineation based on surface geology.