Paleocene-Eocene Drawdown and Refill of the Gulf of Mexico—Concept History and Status
Joshua H. Rosenfeld, 2014. "Paleocene-Eocene Drawdown and Refill of the Gulf of Mexico—Concept History and Status", Sedimentary Basins: Origin, Depositional Histories, and Petroleum Systems, James Pindell, Brian Horn, Norman Rosen, Paul Weimer, Menno Dinkleman, Allen Lowrie, Richard Fillon, James Granath, Lorcan Kennan
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Rosenfeld and Pindell (2002, 2003) hypothesized that late Paleocene-early Eocene docking of the northward migrating Caribbean Plate blocked the 200 km strait between the Florida/Bahamas Block and Yucatan, thereby isolating the Gulf of Mexico from the world ocean (Fig. 1). Within several thousand years, net evaporation in the Gulf lowered its level by about 2,000 meters and formed a land bridge across the eastern Gulf that encompassed Yucatan, Florida, Cuba, and the Bahamas (Fig. 2). Formation of the land bridge was enhanced by isostatic uplift of the basin’s margins as sea level dropped. After about 1 Ma of isolation, reconnection with the world ocean resulted in energetic refill of the basin that cut a deep thalweg between Florida and Cuba (Fig. 3). This relatively short duration drawdown explains many phenomena unique to this period of Gulf history, including:
the excavation of deep canyons across contemporary continental shelves and slopes: e.g., Yoakum (Figs. 4, 5, and 6), St. Landry, Chicontepec/Bejuco-La Laja (Figs. 7 and 8) paleocanyons, and the many canyons found along the lower continental slopes of Florida and Yucatan (discussed below)
salt deposition in the barred Tertiary Veracruz Basin (Fig. 11)
an unconformity in the eastern, carbonate-dominated Gulf Basin (Fig. 12).
The drawdown is coeval with the worldwide Paleocene-Eocene thermal maximum (PETM) possibly triggered by the release of voluminous methane from destabilized hydrates and breached conventional reservoirs of the Gulf at low stand.
The drawdown also profoundly affected the petroleum geology of the Gulf of Mexico, most obviously by deposition of basal Wilcox “Whopper Sand” reservoirs in U.S. and Mexican waters. Further petroleum ramifications include porosity enhancement by fresh water infiltration and leaching of reefal carbonates of the Golden Lane Atoll and deep-water carbonate detritus reservoirs in the Poza Rica Trend and Campeche Sound K/T breccias.
Although a “smoking gun” has not yet been recognized that induces general acceptance of the Paleocene-Eocene Gulf drawdown, convincing evidence may be on the deep-water slopes of western Florida and northeastern Yucatan where sinkholes (Figs. 13 and 14) are present, and steep-walled canyons are observed (Figs. 15, 16, and 17) resembling those along eroded escarpments in present-day sub-aerial environments (Fig. 18).
With increased investigation of the eastern Gulf, the author is confident that definitive evidence will be found that either supports or eliminates the proposed drawdown. Meanwhile, explorers are encouraged to include the idea among their working hypotheses.
Figures & Tables
Sedimentary Basins: Origin, Depositional Histories, and Petroleum Systems
- aliphatic hydrocarbons
- Atlantic Ocean
- Caribbean Plate
- Caribbean region
- chemically precipitated rocks
- continental shelf
- continental slope
- Gulf of Mexico
- North Atlantic
- organic compounds
- Paleocene-Eocene Thermal Maximum
- plate tectonics
- sea-level changes
- sedimentary rocks
- Straits of Florida
- United States
- Yucatan Peninsula