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Consulting in:
Sedimentology, Sequence Stratigraphy &
Climate- & Sea-Level Change


Geological evolution of Venezuela-Trinidad reassessed: Protocaribbean-Caribbean foreland basins (Campanian to Recent) and Neogene wedge-top halite-dissolution basins

by Roger Higgs ©Geoclastica Ltd 2005


The evidence for a subsurface, dissolving, "Carib Halite Formation" detailed in this report, plus major changes to the "Caribbean Oblique Collision Model", will affect petroleum exploration in Ecuador, Colombia, Venezuela and Trinidad, providing new interpretations (predictions) of subsidence history, heatflow/maturation history (later rifting), paleogeography, etc. Many new plays will emerge. For example, the concept of a Proto-Caribbean Foreland Basin reaching from Ecuador to Trinidad, with dual, orogen- and craton-derived, Campanian and younger sand fairways is new (contrast the old model of a single, passive-margin fairway succeeded by dual Caribbean fairways). Large or giant oilfields occur both in the orogen fairway (e.g. Angostura and Brighton in Trinidad) and in the craton fairway (e.g. Barco & "lower Mirador" at Cusiana; Misoa fields; "Naricual"/Merecure at El Furrial), serving as analogues for future exploration. The recognition that the Cusiana, Misoa and El Furrial reservoirs reflect Proto-Caribbean rather than Caribbean nappe loading has many exploration implications. Appreciation that there are four generations of foreland basin in Venezuela (Proto-Caribbean, Caribbean, Catatumbo, Merida) will help explorers to develop more sophisticated and reliable models of oil and gas generation, migration and entrapment.

The Carib Halite concept is important for exploration, as it predicts evaporite-related source rocks, anomalous heatflow (high halite conductivity), and structures related to decollement, halokinesis and dissolution collapse. Halite dissolution also offers a discrete suite of additional exploration targets in the form of Neogene supraorogen basins like the Gulf of Paria. The popular pullapart model for the Gulf of Paria, implying gross palinspastic-paleogeographic distortion of Trinidad by E-W strike slip, is incorrect. The potential for new finds of emeralds and other evaporite-associated minerals (e.g. silver, malachite) in northern South America is also high.


This report presents the Jurassic to Recent evolution of the Ecuador-western Colombia-northern Venezuela-Trinidad region (the companion report treats Trinidad in more detail), covering the majority of basins in NW Colombia, Venezuela and Trinidad, and detailing the diverse evidence for deep-halite dissolution (from outcrops, wells and seismic profiles; such evidence may include known sub-commercial metalliferous deposits, offering a new model for metals exploration) and for long-lived northern provenance (based on southward fining, olistolith compositions, cannibalization and heavy minerals). The report is a painstaking synthesis of the Spanish and English literature, with the added benefit of the author's 19 years of experience in the region, conducting outcrop and subsurface studies, including three years as clastic-sedimentology consultant to Petróleos de Venezuela. No previous report or publication has described and interpreted these countries as a unified entity, in such detail. Numerous enigmatic Venezuelan formations are analysed and demystified (e.g. "basal Vidoño limestone", "Corazón limestone", Caratas, Tinajitas, "Lecherías").

The text integrates and interprets a vast amount of data, leading to the main conclusions above. Products include 8 tectonogeographic maps (Maastrichtian-Pliocene) and 5 tables of data (olistolith compositions, heavy minerals, known evaporite occurrences, halite-dissolution basins, and analagous basins worldwide).

With the strong likelihood of extensive exploration-block offerings in Venezuela over the next five years, and frequent bid-round and farmin opportunities in Trinidad, onshore and offshore, no exploration company interested in this prolific petroleum province should be without this report, which both BP and BHP have bought.

202 pages, 6 tables, 46 figures.

Download list of contents (pdf 65 KB)

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