Petrology and geochronology of an arc sequence, Bonaire, Dutch Antilles, and its relationship to the Caribbean Plateau
thesisposted on 15.12.2014, 10:39 by Patricia Maeve Eleanor. Thompson
Oceanic plateau rocks, island arc fragments and tonalitic batholiths are juxtaposed on the southern Caribbean margin, and appear to be both spatially and temporally related. It is widely accepted that the plateau originated in the Pacific realm, and although there is no consensus as to which hotspot it was derived from, Galapagos is frequently cited. A previous study concluded that one of the tonalitic batholiths, the 85 Ma Aruba batholith was generated from the first stages of subduction beneath the 90 Ma plateau, following a subduction polarity reversal.;Until this study, little was known about the genesis of the arc sequences associated with the plateau, and their tectonic significance. This work focuses on the volcanic sequence exposed on Bonaire, and uses field, geochemical, isotopic and geochronological constraints to confirm that it is an arc sequence, and to reveal that the arc sequence is genetically unrelated to the plateau and the batholith. It formed as part of an oceanic arc at 95 +/- 2 Ma, prior to plateau formation.;In addition, Hf-Nd isotopes are used to fingerprint both the Caribbean plateau and the Galapagos plume, and support a genetic link between the two. The arc most likely originated in the Pacific, along with the Caribbean plateau, and was later swept up in front of the eastwards moving plateau, and eventually accreted onto the Southern Caribbean margin.