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A more complete crustal perspective of the northernmost part of the Venezuela Basin is provided by data from an international public database processed with new geomagnetic models (CM4) together with data from aeromagnetic surveys and from a recent marine cruise in areas offshore Puerto Rico and the Dominican Republic. The magnetic anomaly map set off three main domains: the North Atlantic plate, a narrow zone extending from the Dominican Republic to Puerto Rico-Virgin Islands, and the North Caribbean Plate. We focused mainly on the latter, applying the Euler deconvolution algorithm in the Venezuela Basin. Shallow and middle depth sources (located between 2km and 12km) are inferred to be the dominant sources (85%), while deep sources are located mostly in the Venezuela Basin, and scarcely appear in the Beata and Aves Ridges. We performed 2D+1/2 modeling on an eastwest transect, using Bouguer gravity and magnetic anomaly data to derive a more detailed crustal description of the northern part of the Venezuela Basin. The model suggests that in the Caribbean crust, long wavelengths (>200km) are controlled by variations in crustal thickness, whereas the intermediate ones (50-100km) are mainly controlled by variations in their magnetic properties. It also suggests the presence of a local anomalous body located in the east-west transect, between 487km and 560km, displaying a remarkable positive magnetization contrast (0.3 SI) with regard to the rest of the basin. This body shows a slight increase in density (3010kg/m3), and extends from the bottom of the UCL (Underplate Cumulate Layer) to a depth of 7.5km. We correlate it with the volcanic wedge reported by Driscoll and Diebold (1998).

Located in Central Hispaniola, the Pelona-Pico Duarte basalts Formation (Fm.) offers an opportunity to study the Late Cretaceous Caribbean large igneous province magmatism on land. It is composed by a ~2.5km-thick pile of massive and monotonous submarine flows of basalts, locally intruded by synvolcanic dikes and sills of dolerite. The Pelona-Pico Duarte basalts Fm. was emplaced onto Turonian-Lower Campanian island-arc volcanic and sedimentary sequences, and is overlain by Maastrichtian platformal carbonates. Two 40Ar/39Ar plateau ages indicate both extrusive and intrusive magmatic activity at least during the 79-68Ma interval (Middle Campanian to Maastrichtian), so the magmas were in part coeval with the late phases of the Caribbean large igneous province. The basalts have a restricted major-and trace-element, and isotopic, compositional variation. For a range of 47.6- 50.2wt.% SiO2, the Pelona-Pico Duarte basalts Fm. has relatively high contents in TiO2 (1.5-3.6wt.%) and Fe2O3T (10.7-13.1wt.%). On the basis of MgO contents, samples can be classified into tholeiitic basalts (lt;8wt.%) and high-Mg basalts (8-12wt.%). Mineral assemblages and major element compositional trends indicate that basalts derived from tholeiitic parental magmas by fractionation of olivine plus spinel, clinopyroxene and orthopyroxene, observed as microphenocrysts, as well as plagioclase and Fe-Ti oxides. In a MORB-normalized multi-element plot, the basalts have light rare earth elements (LREE) enriched ([La/Nd]N=1.5-2.2) and heavy rare earth elements (HREE) depleted ([Sm/Yb]N=2.1-3.7) patterns, with very high Nb contents (11-30ppm). These patterns and the values of trace element ratios (K/Balt;20, Ti/Vgt;20 and Zr/Nblt;10) are characteristic of transitional and alkalic oceanic-island basalts. In terms of Sr-Nd isotopic composition, the samples are homogeneous and enriched relative to older Caribbean large igneous province units in Hispaniola, with (87Sr/86Sr)i ratios between 0.70330 and 0.70348 for a very restricted range of (eNd)i values between +5.0 and +5.9 (where i=70Ma). The Pelona-Pico Duarte basalts Fm. are interpreted as partial melts of a plume-related, deep enriched source, which have not been contaminated by active subduction. Mantle melt modelling indicates that both high-Mg basalts and basalts formed by mixed melts of both garnet and spinel lherzolite in variable amounts. Melts incorporated at different mantle depths, most probably in relation to the melt column processes in an upwelling plume. The Pelona-Pico Duarte basalts Fm. has significantly different values of petrogenetic tracers compared to underlying arc-related lavas, indicating a fundamental change in the mantle sources. It has geochemical affinities with the mantle domain influenced by the Late Cretaceous Caribbean plume, suggesting that enriched mantle was flowing toward the NE, to the mantle wedge region of the Caribbean island-arc, in response to rollback of the SWdirected subduction of the proto-Caribbean slab

Oceanic crust was generated at multiple spreading centres during the Jurassic and Early Cretaceous, forming a “proto-Caribbean” oceanic domain. During the Cretaceous, part of that crustal domain thickened into an oceanic plateau, of petrologic Mid-Ocean Ridge (MOR) to Ocean Island Basalt (OIB) affinity. Simultaneously, the South and North American continental plates developed rifting and tholeiitic magmatism in the Middle America region (Venezuela and Cuba). The rifting created space for the proto-Caribbean oceanic domain. Petrological and regional correlations suggest that, beginning in the Cretaceous, the proto-Caribbean domain was involved into two main stages of subduction, referred to as first and second “eo-Caribbean” phases. Each phase is characterized by oblique convergence. The older (mid-Cretaceous) stage, involved in subduction (probably eastward dipping) of thin proto-Caribbean lithosphere, with generation of Island Arc Tholeiitic (IAT) and Calc-Alkaline (CA) magmatism, accompanied by high pressure - low temperature (HP - LT) metamorphic effects, and formation of arc units and ophiolitic melanges (Guatemala, Cuba, Hispaniola and Puerto Rico, in the northern margin; Venezuela in the southern). The Late Cretaceous second stage consisted of westward dipping intra-oceanic subduction; it is recorded by tonalitic arc magmatism related to the onset of the Aves - Lesser Antilles arc system. Since the Late Cretaceous, the inner undeformed portions of the Caribbean oceanic plateau (i.e. the Colombian and Venezuelan Basins) were trapped east of the Pacific subduction of the Chortis, Chorotega and Choco blocks, ultimately building the Central American Isthmus. From Tertiary to Present, continuous eastward movement of the Caribbean Plate with respect to the Americas, gave rise to transpression along both the northern and southern margins, marked by scattered and dismembered ophiolitic terranes.

Arguments in support of the Pacific origin for the Caribbean Plate are discussed along with others that point to an inter-American origin. Entry of a Pacific-derived plate would have involved unlikely, geometrically complex and highly diachronous events. They would have included changes in direction of subduction, changes in direction of plate migration, major (1000s of km) plate migration, major rotation of large parts of a volcanic arc, major rotations of the Maya and Chortis blocks and diachronous development of flysch/wildflysch deposits as the entering plate interacted with neighbouring elements. The internal structural conformity of the Caribbean Plate and of the Maya and Chortis blocks with regional geology of Middle America shows that no major migrations or rotations have occurred. Coeval, regional deposits of Albian shallow water limestones, Paleocene– Middle Eocene flysch/wildflysch deposits, Middle Eocene limestones, and a regional Late Eocene hiatus show an inter-American location, not a changing Pacific-Caribbean location. Neogene displacement of the Caribbean relative to North and South America amounts to no more than 300 km.

The Cretaceous succession in Jamaica can be divided into sedimentary packages bounded by major unconformities (synthems). On the base of biostratigraphy and ages derived from strontium isotope ratios, these unconformities have been dated as Early Santonian, Late Campanian-Early Maastrichtian and Early Eocene. Each unconformity is also characterised by the widespread deposition of shallow water limestones, and a further shallow limestone depositional event occurred in the late Middle Campanian. Some unconformities can be related to known tectonic events (based on either Burke-type or Pindell-type models) that affected the Caribbean region. The Early Santonian event is widespread and occurred shortly after the creation of the Caribbean Large Igneous Province. The late Middle Campanian shallow water limestone event could correlate to the reversal of the Great Arc of the Caribbean in Burke-type models, but is unrepresented in Pindell-type models. The Late Campanian-Early Maastrichtian unconformity is related to the first collision of the Caribbean Plate with North America in both Burke-type and Pindell-type models. The Early Eocene event is associated with the onset of rifting that controlled Tertiary depositional patterns across Jamaica.