Caribbean crustal provinces; Seismic and gravity evidence
Numerous geoscientists have proposed and evaluated many conceptually distinct models for the evolution of the Caribbean region since 1930 (Fig. 1). From these, seven predominant interpretations of Caribbean crustal generation and modification have emerged: (1) sea-floor spreading, involving mid-ocean rifting, tectonic convergence, subduction, and back-arc spreading (for examples, see Pindell and Barrett, this volume); (2) basification of continental crust (Skvor, 1969); (3) lateral shear and transverse extension with attenuation, a variation on plate-tectonic theory (Ball and Harrison, 1969); (4) in situ orthogeosynclinal crustal evolution (Khudoley and Meyerhoff, 1971; Meyerhoff and Meyerhoff, 1972), a process classically associated with the tectogene hypothesis; (5) magmatic crustal thickening, related to magmatic-arc emplacement near subduction zones, to "hot-spot" magmatism (Officer and others, 1957; Duncan and Hargraves, 1984), to basaltic intrusion (Burke and others, 1984), and to flood-plateau basaltic volcanism (Donnelly, 1973; Donnelly and others, this volume); (6) tectonic crustal thickening and crustal accretion: processes in which tectonites are formed, assembled, or reassembled at convergent plate margins into masses reaching continental thickness (MacDonald, 1972a, b); (7) another process, involving thermal contraction and attendant mantle surges, is described by Morris, Meyerhoff, and others in this volume.
Most of these processes lead to three genetically distinct types of crust (Ewing and Press, 1955; this paper): (1) oceanic, (2) continental, and (3) accretionary. Physical and genetic aspects of these crustal types are discussed below. Crust that cannot be readily assigned to one of these classes is, temporarily at least, categorized as indeterminate.
Knowledge of Caribbean crustal evolution has emerged