ABSTRACT

Tectonic hypotheses regarding the Caribbean region fall into three main categories: 1) geosynclinal troughs at times separated one or several landmasses from the main continents to the north and south, with subsequent foundering or basification of part of the landmasses accounting for the present sea areas, 2) a long-standing open seaway connected the Atlantic and Pacific oceans separating the continents of North and South America, and 3) a single large continent was divided into two major parts by a region of structural weakness, along which it drifted apart subsequently, originating the Caribbean sea along the rift zone. Pre-Mesozoic rocks of Central America's core include possible Precambrian and early Paleozoic metamorphics, and Pennsylvanian-Permian sediments. They form the oldest terrain in the northern Caribbean region. Some hypotheses relate them to Mexico, while others, in explaining the Gulf of Mexico as a result of continental drift, consider them as part of the Appalachian mountain system. A comprehensive explanation of continental drift for the region should look for possible relationships between these rocks and the Paleozoic metamorphic and sedimentary rocks of Colombia and Venezuela.

The early Mesozoic record in northern Central America is poor; it has been interpreted as a time of regional emergence, with sedimentation restricted to narrow areas during short time spans. If the main drifting and separation of the North and South American continents took place during early Mesozoic time, the geologic histories of northern Central America and northern South America should show similarities. From Late Jurassic to early Tertiary the geologic history of northern Central America can be clearly correlated with the Mexican geosyncline and to an extent with the Greater Antilles. Because southern Central America, like a large portion of the Greater Antilles, presents an oceanic basement that originated during middle to late Mesozoic time, these two areas should not be considered in any pre-Mesozoic paleogeographic reconstruction. The major features of northern Central America, parts of southern Central America, the Greater Antilles and northern South America are of Laramide origin, though the details of the deformational episodes are different in each area and the intensity of the orogeny was not uniform. Two major regional features were well defined during, or shortly after, the Laramide deformation: these are the emplacement of most of the circum-Caribbean serpentinites and the definition of the large fault zones that limit the Caribbean sea on its northern and southern boundaries. In some cases, however, the serpentinites were emplaced and the fault zones were originated during earlier tectonic events. The serpentinites belong to three belts: 1) northern Central America-Greater Antilles, 2) northeastern Colombia-Venezuela, and 3) western South America-southern Central America.

Post-Laramide tectonics were controlled by a stable Caribbean area divided in small crustal blocks, separated by large faults with considerable horizontal and vertical displacement. The late Tertiary tectonics of Central America are related mainly to features and movements in the eastern slope of the East Pacific Rise, and show little connection with the Caribbean.