ICE 2022


Recent literature, exploration studies, and internet posts continue to question the Pacific origin of the Caribbean oceanic lithosphere. As presented, these viewpoints appear to result from misunderstanding of geologic data and processes. A review of original and newer data/arguments greatly supports the Pacific origin and explains key issues causing apparent misunderstanding. I argue that the negative perceptions of the Pacific origin are over-feared. 1) An in-situ interpretation is attractive because it would allow for direct basinward extrapolation of northern South America’s (nSoAm) onshore petroleum systems. However, nSoAm’s (and Guatemala’s) petroleum habitat has little to do with the Jurassic. Although in-situ models would predict marine Jurassic on the Caribbean seafloor, such a section would be completely unrelated to nSoAm’s prolific petroleum systems. 2) nSoAm’s Turonian-Coniacian-Santonian primary source rock section is, in fact, present in most of the Caribbean basins. The uncertainty regarding its potential concerns not presence but thickness and richness, both of which would be primary concerns whether the lithosphere was Pacific-derived or not. The view that this source section is thin likely pertains to DSDP/ODP having drilled only basement highs, leaving more favourable lows untested. 3) By the time of Turonian-Santonian source rock deposition, the Pacific origin model places the Colombian and Venezuelan basins west of Colombia and south of Mexico, with Caribbean–American tectonic interactions already underway. I see no reason why an oceanic position north of nSoAm (in-situ model) should have been more favourable to source rock deposition of this age than a position directly to the west (Pacific model). 4) Although more quartzose reservoir detritus might have reached the Colombian Basin earlier in in-situ models, the Pacific model allows for plenty of sand to reach it eventually. In fact, the later arrival of these sands in the Colombian Basin (relative to in-situ models) might enhance HC potential by triggering younger critical moments in maturation due to late burial, and by allowing more structures to pre-date maturation. 5) Backstripping suggests the Caribbean Plateau crust was quite shallow (locally emergent) in the Late Cretaceous, negating the need to invoke abyssal source rock depositional models in many areas. In summary, there is no great reason to resist the obvious Pacific origin when exploring in the Caribbean.