Origin of the Aves Ridge and Dutch–Venezuelan Antilles: interaction of the Cretaceous ‘Great Arc' and Caribbean–Colombian Oceanic Plateau?

Abstract

In this paper we reassess the geochronology and geochemistry of three dredge hauls from the SE corner of the Aves Ridge (Caribbean Sea) originally sampled in 1968 by Duke University's R. V. Eastward. Two hauls consist of light rare earth element-enriched granitoids with a U-Pb zircon emplacement age of 75.9 +/-0.7 Ma. A further haul contains mostly calc-alkaline island arc basaltic andesites of uncertain age. Petrological, trace element and isotopic constraints indicate that the granitoids have an oceanic crustal source and were formed by melting of the lower arc, oceanic or oceanic plateau crust. The mafic rocks formed by partial melting of an incompatible trace element-enriched mantle wedge, which was probably composed of mantle plume material. Both the dredged rocks and data from the Dutch-Venezuelan Antilles indicate a period of west-dipping underthrusting and subduction beneath, or close to, the Caribbean-Colombian Oceanic Plateau between c. 88 and c. 59 Ma, concurrent with collision of part of the plateau with northwestern South America. Constraints from the geochemistry and geochronology of offshore southern Caribbean arc and plateau rocks suggest that in the southern Caribbean there was no pre-existing west-dipping subduction system during formation of the Caribbean-Colombian Oceanic Plateau, whereas long-lived SW-dipping subduction in the northern Greater Antilles is more probable.

Kinematic reconstruction of the Caribbean region since the Early Jurassic

“…These rocks are interpreted to have formed above a depleted mantle (Wright and Wyld, 2011). No CLIP material has been found on La Blanquilla and Bonaire (Neill et al, 2011). On Aruba, Curaçao and Gran Roque however, gabbros and dolerites of CLIP affinity are present (Giunta et al, 2002b).…”

“…Aruba, Curaçao, La Blanquilla and Gran Roque of the Los Roques contain magmatic rocks that are geochemically very similar to the island arc rocks from the southern Aves Ridge (Neill et al, 2011). Granodiorites and tonalites of La Blanquilla are dated at 75.5 ± 0.9 Ma and 58.7 ± 0.5 Ma respectively, the Aruba batholith at 88.6 ± 0.5 Ma (U-Pb ages of van der Lelij et al, 2010;Wright and Wyld, 2011) and dikes of diorite on Curaçao at 86.2 ± 1.1 Ma (Wright and Wyld, 2011).…”

“…Here, we particularly focus on ages of magmatism (e.g., oceanic island arc rocks), to infer the presence of a convergent plate boundary for that period. The geochemical literature of the Caribbean contains a large number of models invoking major geodynamic events such as subduction polarity reversals or slab break-off episodes, and complex subduction zone configurations (e.g., Meschede and Frisch, 1998;Kerr et al, 1999;Neill et al, 2011;Hastie et al, 2013). Such interpretations are not a priori followed here, but rather, our reconstruction may serve as an independent kinematic basis to evaluate the kinematic feasibility of such scenarios.…”

“…The ridge contains granodiorite, diabase, porphyritic basalt and metabasalt (Fox and Heezen, 1975;Neill et al, 2011) and has a similar seismic velocity structure and crustal thickness as the Lesser Antilles Arc (Christeson et al, 2008). The arc was active in at least the Late Cretaceous and Paleocene (Fox and Heezen, 1975;Pinet et al, 1985;Bouysse, 1988) indicated by ages of dredged and drilled volcanic rocks ranging from 88 to 59 Ma (Neill et al, 2011). No CLIP material has been reported from the Aves ridge.…”

“…Accumulation of the Barbados Accretionary Prism since the Early Eocene indicates ongoing convergence during the 50-0 Ma period. Arc volcanics in the Lesser Antilles Arc and Aves Ridge are dated ranging from 38 to 0 Ma (Briden et al, 1979) and from 88 to 59 Ma (Neill et al, 2011) respectively, suggesting that the transition of the active arc from the Aves Ridge to the Lesser Antilles Arc took place between 59 and 38 Ma. We followed the model of subduction system evolution of Aitken et al (2011), considering the Grenada Basin to be the forearc of the Aves Ridge that widened by E-W extension in the Paleocene-Middle Eocene, after which active volcanism ceased in the Aves Ridge and migrated to the Lesser Antilles Arc, separating the former forearc into the Grenada and Tobago Basins.…”