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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 10 (1926)

Issue: 4. (April)

First Page: 382

Last Page: 404

Title: Original Source of Oil in Colombia

Author(s): F. M. Anderson


The Cretaceous rocks of Colombia, including the Jiron, Villeta, and Guadalupe groups, have been laid down upon an ancient floor of metamorphic and crystalline rocks. The lower and upper groups of the Cretaceous are very largely detrital in origin, while the middle group is partly detrital and partly of organically derived limestones and marls. Dr. Otto Stutzer has claimed that "All of the oil in Colombia probably emanated from the Villeta group, that is, the Lower Cretaceous." There are no wells yet drilled in Colombia that derive a production from Cretaceous beds, nor is any part of the Cretaceous more than sparingly bituminous, although suitable structures are abundant.

On the other hand, all of the producing wells in Colombia are in Tertiary formations and are drilled in situations such that it appears highly improbable that the oil could have emanated from Cretaceous strata, especially from the Villeta group. Moreover, the older Tertiary (Eocene and possibly Oligocene) strata are in many places richly organic and more highly bituminous than the Cretaceous and the producing wells have been drilled into them, and the presumption is strong that they have been the primary source of the oil that is being produced.

In parts of Colombia where the older Tertiary beds are purely marine, foraminiferal remains are abundant and could constitute the source material of the oil. In other parts of the country where the older Tertiary beds are non-marine they include lignitic and carbonaceous strata, such as might have contained the source material of the oil, as is the case in Trinidad and, perhaps, also in some of the oil fields of the Maracaibo basin in Venezuela.

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