Early Paleogene Isolation of the Gulf of Mexico from the World's Oceans; Drawdown and Refill

Deep paleocanyons across shelves and slopes, sudden deposition of massive sandstones hundreds of kilometers from paleoshelf margins, salt and redbeds in the Veracruz Basin, and an unconformity marked by paleokarst near the mouth of the Gulf are among a series of unusual features most easily explained by a short-lived Late Paleocene-Early Eocene sea level drawdown of the Gulf of Mexico. The trigger for this event would have been closure of the 200 km wide deep water strait between the Gulf and the world ocean by the northward advancing Caribbean Plate (Cuban Arc) as it docked against the high-standing Yucatán and Florida-Bahamas blocks.

Evaporation would have far exceeded rainfall and runoff into the isolated basin, thereby lowering the Gulf by ~2,000 meters within a few thousand years. The release of hydrocarbon gases from hydrates and disrupted thermogenic reservoirs may have triggered the Paleocene-Eocene Thermal Maximum.

The barrier was breached after about 1 Ma when Cuba moved to the east relative to Yucatán. A deep erosional thalweg in the eastern Gulf formed during rapid refill of the basin.

Little information has been released to either support or condemn this idea since it was first proposed in 2003, possibly because of the difficulty of communicating among U.S., Cuban and Mexican investigators. Moreover, the petroleum companies working in these areas have been reluctant to release information of a confidential nature. In spite of these obstacles, we believe that the idea merits dedicated investigation by industry and academic scientists.