Regional Geophysics and Geochemistry
The distribution of small earthquakes recorded during the last 35 years, of large earthquakes during the last 400 years, as well as focal mechanisms determined for moderate earthquakes, have provided insights into the location of, and style of motion on, the margin of the Caribbean plate. In this chapter we review information gained by seismological means to help define the nature of the Caribbean plate and its boundaries. The location of the Caribbean plate boundary is more clearly defined along its eastern, western, and northwestern margins (the Lesser Antilles and Central America); other portions are more complex and still subject to general debate (Fig. 1). The first Caribbean-wide study of seismicity by Sykes and Ewing (1965) delineated several features, including westerly and southerly dipping seismic zones in the Lesser Antilles and eastern Greater Antilles, respectively; a strong source of intermediate-depth events beneath eastern Hispaniola;and shallow-focus earthquakes extending from Central America through the Greater Antilles, as well as along northern South America. Work by Molnar and Sykes (1969) determined the general shape of the easterly dipping seismic zone in Central America, several focal mechanisms consistent with underthrusting of sea floor along the eastern and western margins of the Caribbean plate, and left- and right-lateral motion along segments of the northern and southern margins, respectively. They also estimated 0.5 and 2.0 cm/year as the minimum rates of seismic slip at the Lesser Antilles and Middle America subduction zones. These and other studies clearly demonstrated that the Atlantic Ocean sea floor of
Figures & Tables
The result of a major international effort involving authors and organizations from 13 countries, this volume summarizes the complex geology and tectonic evolution of the Caribbean plate and its relation to the adjacent North American, South American, Nazca, and Cocos plates. Focuses on regional geology and geophysics, magmatic processes, neotectonic features, geologic hazards, and energy and metallic resources. Contrasting views for the Mesozoic and Cenozoic geological evolution are presented in chapters on plate tectonics and mantle surge tectonics. Chapters on marine geology and geophysics are new syntheses for the entire Caribbean region. Highlights of the volume include extensive bibliographies and new syntheses of stratigraphic-lithologic columnar sections, seismicity, gravity and magnetic anomalies, neotectonic features, resource data, and crustal properties.