Analysis of Provenance of Late Cretaceous – Eocene Flysch Sequences in Northern Venezuela; Tectonic Implications on the Evolution of the Caribbean
Mariela Noguera and Jim E. Wright
University of Georgia, Department of Geology Athens, Georgia; [email protected]
Tectonic reconstructions suggest the oblique collision between the so called Great Arc of the Caribbean and the South American plates began in the Late Cretaceous/Paleocene. During the collision turbiditic sequences were deposited and later deformed and uplifted as the Caribbean plate moved eastwardly. As a result, a “belt” of flysch units can be observed along northern Venezuela (Matatere, Guárico, Garrapata, Caratas and Los Arroyos formations), Curacao and Trinidad. These sequences are believed to have a mixed provenance from sources located at the North (volcanic arc) and South (continental). Ages of deposition of these units have been determined from the scarce fossil record and stratigraphic correlations. Our petrographic and U-Pb detrital zircon data, from Paleocene/Eocene turbidites on Curacao, support a mixed arc/continental margin provenance, probably related to rapid exhumation of passive margin units and from the Aves Ridge/Leeward Antilles. Caribbean models suggest that the oldest arc rocks should be Early Cretaceous whereas our detrital zircon data indicate only Late Cretaceous (75-89 Ma) and younger ages. Our preliminary interpretation is that arc magmatism initiated along the Aves Ridge/Leeward Antilles in the Late Cretaceous and was constructed on a basement of the only slightly older Caribbean Large Igneous Complex (CLIP). Thus, the Aves Ridge/Leeward Antilles do not have a Greater Antilles arc basement. We suggest that the Greater Antilles arc terminated southward at a transform boundary that separated proto-Caribbean oceanic crust from the Greater Antilles arc and the CLIP. Subduction initiation along the transform generated the Leeward Antilles/Aves Ridge island arc.
AAPG Search and Discovery Article #90083 © 2008 AAPG Foundation Grants in Aid