Caribbean Geology, 1970
Author: Nagle, Fred
Source: Bulletin of Marine Science, Volume 21, Number 2, June 1971 , pp. 375-439(65)
Abstract:Portions of Caribbean land and marine geology, based on data available through 1970 and early 1971, are summarized in an effort to present the known tectonic framework as well as to stimulate further attempts to integrate the geology of the Caribbean area into the new global tectonics.
Other than in Cuba, the oldest known rocks in the Greater Antilles are Cretaceous. Pre-Mesozoic rocks may be present in parts of Cuba, Hispaniola, and southwestern Puerto Rico, but metamorphism has complicated interpretations of age.
The Lesser Antilles are generally assumed to be younger than the Greater Antilles, but radiometric dates from Desirade suggest some continuity of igneous activity between the two regions. Recent work suggests that the Lesser Antilles are presently cross-faulted into individual blocks, with each one developing its own stress pattern during sea-floor spreading. However, basement structures of the Lesser Antilles may continue to at least as far as 65°W; both geological and geophysical evidence indicate that a south Caribbean fault does not exist.
Paleozoic rocks are known to underlie part of the Yucatan and central Florida, but the nature of the basement under the Bahamas and Blake Plateau is unknown. However, striking similarities in the Cretaceous to Recent geology of these areas and that of northern Cuba suggest that this entire region has behaved as a unit since the Cretaceous.
The Yucatan Basin and Cayman Trough contain the thinnest crust (9 km and 6 km) in the Caribbean area. These two features are separated from one another, and from the Gulf of Mexico to the north, and the Colombian Basin to the south, by parallel ridges or welts of continental crustal thickness. One or more of these positive features may contain pre-Mesozoic rocks.
The Cayman Trough is not a westward continuation of the Puerto Rico Trench, and may be a much younger feature.
Vertical tectonics dominate the Late Cretaceous to Recent geologic history all around the Caribbean, through the Greater and Lesser Antilles, as well as along northern Colombia and Venezuela. Land and marine evidence for extensive wrench faulting after the Late Cretaceous is slim. Prior to that time, fault motion in most areas is unknown or nonexistent.
Earthquake first motion studies indicate active wrench faulting on both the northern and southern Caribbean margins, as well as underthrusting in the Lesser Antilles and in the northeast Hispaniola region. Such studies indicate nothing concerning past motions.
Although several radically different tectonic models have been proposed to explain the origin of Caribbean geologic features, no one model has captured the enthusiasm of the majority of investigators.
Document Type: Research Article
Publication date: June 1, 1971
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