READERS’FORUM: Caribbean Origins
02 September 2013
In the July EXPLORER’s Historical Highlights column, James Pindell, a well-known advocate for the Pacific origin of the Caribbean Plate, closes his interesting article with the following sentence: “Among the true paleogeographic questions today is not IF the Caribbean is Pacific derived, but HOW and WHEN west-dipping subduction of Proto-Caribbean crust began.”
According to him, then, the debate about the origin of the Caribbean is closed, with no alternative geological interpretations or possibilities.
From a purely epistemological perspective, giving the nature of our science, Pindell’s theory about the Caribbean sums up to an elegant and complicated model that represents only a single alternative, and is consistent with a series of observations in the northern part of the Caribbean, especially from Hispaniola to the Lesser Antilles and Venezuela.
However, this single model appears to lack some consistency when it comes to explaining some of the observed features found along the Caribbean coast of western Colombia, south of the Chimare Suture, from the Guajira Peninsula to Panama.
The so-called Great Arc of the Caribbean (GAC), the island arc produced by the subduction of the proto Caribbean underneath the Current Caribbean Plate, and that, according Pindell’s model, should be present in Colombia’s west Caribbean region, is conspicuously absent along the entire coast, or it is yet to be found.
From the Lower Magdalena Valley (LMV), the San Jacinto and Sinú belts (figure above), they represent a transition from the eastern continental crust below the LMV to an accretionary prism or thrust belt, depending on the author, without any clear presence of island arc-related lithologies. Further north, in the Guajira Offshore area, wells penetrated Cretaceous granites of continental affinity and Triassic Granodiorites that are hard to explain with Pindell’s current model.
Furthermore, most gravity 2-D forward models in the area are consistent with continental-affinity blocks that stretch out in to deeper parts of the offshore basin, and do not support the presence of the Circum Pacific Suture in the Guajira basin.
Far from been proved, the question about the Pacific affinity of Caribbean in western Colombia today is WHERE the GAC is, and WHY, if it exists, is not as pervasive and prominent as in the Northern Caribbean basins.
I found it problematic, to say the least, to declare the debate about the Caribbean plate closed when such a vast area with a complicated geological evolution has been subject to so little detailed studies. Exploration activities in the southern Caribbean Basin are in their infancy, and nothing is more dangerous than to approach these frontier basins with a fixed model and a closed mind that, in many instances, condemn the prospectivity of what could become a new offshore petroleum province.
It simply is contrary to the very nature of our fascinating science
Jim Pindell (“Origin of the Caribbean? Look Toward the Pacific,” July EXPLORER) fails to acknowledge literature that contests the Pacific origin of the Caribbean, including the contents of a book (GSL Special Publication 328) that lists him as co-editor.
One can deny data and opinion, but they will not go away. Discussion and debate would be more constructive. I will address his arguments in a later article.
Meanwhile, see the important, upcoming program of Caribbean investigation described in September’s Explorer.