Abstract

RINCON-MARTINEZ, Daniel et al. Mineralogical and geochemical evidence of the Caribbean Large Igneous Province (CLIP) in the submarine basement of the Guajira Basin, Colombia. Bol. geol. [online]. 2025, vol.47, n.1, pp.13-41.  Epub May 06, 2025. ISSN 0120-0283.  https://doi.org/10.18273/revbol.v47n1-2025001.

The origin and composition of the basement offshore of the northern South American margin are somewhat controversial as it results from the complex interaction of the Caribbean, South American, and Nazca tectonic plates through geologic time. One of the major issues that have limited a proper comprehension is the difficulty in acquiring sampling from submerged igneous and metamorphic rocks. The basement sequence of the Orca-1 exploratory well, located offshore of the Guajira Peninsula in northern Colombia, consists of a sequence at least 200 m thick, characterized by basalts and andesites. Occasional extrusive episodes are marked by the presence of pyroclastic rocks deposited in a subaqueous environment. The mineralogical alteration of the Orca-1 rocks points to a significant role played by low- temperature hydrothermal fluids in their formation. Its geochemical signature indicates a tholeiitic affinity and a plume source without any evidence of a subduction component or mantle-crust interaction in its petrogenesis. Based on their composition, we propose that the Orca-1 basement rocks correspond to a fragment of the oceanic crust that formed the Caribbean Large Igneous Province (CLIP) and were later accreted to the margin of the Guajira Peninsula, north of the Chimare suture which seems to be northern boundary of the autochthonous South American blocks.

Keywords : Basement rocks; Caribbean Plate; Caribbean Large Igneous Province (CLIP); Petrography; Geochemistry; Guajira offshore Basin.

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