Formation of the DeSoto Canyon, Northeastern Gulf of Mexico

The DeSoto Canyon is a prominent undersea canyon cutting into the continental shelf south of Pensacola, Florida in the northeastern Gulf of Mexico. It separates a predominantly clastic province to the northwest typified by the Mississippi Fan, from the carbonate province to the southeast typified by the Florida Escarpment. This depositional boundary and current-induced erosion have been speculated to be the causes for the canyon's formation. Examination of seismic and well data in the region of the canyon suggests that there may be other factors in its formation, including the Chicxulub impact.

In the vicinity of the canyon is the DeSoto Canyon Salt Basin which dates back to the rifting stage of the Gulf of Mexico in the Early Jurassic. Although this basin was a significant depositional feature during the Jurassic, continuous, parallel reflectors seen on seismic suggest that the basin had little effect on deposition during the Early Cretaceous and that the canyon had not yet formed. Progradation from the northwest was initiated during the Late Cretaceous, possibly producing a broad low connected to the Suwannee Channel. The oldest indication of canyon formation is an erosional boundary at the top of the progradational wedge, cutting down to the Lower Cretaceous at the deepest part of its channel. This horizon can be tied to the K/Pg boundary in nearby wells, suggesting a potential relationship with the Chicxulub impact. We hypothesize that the Suwannee Channel may have acted as a funnel for tsunami waves propagated by the impact, magnifying their effect in the area and producing instability sufficient to cause mass wasting and initiation of canyon cutting. Although the channel has undergone minor migration during the Cenozoic, the canyon appears to be held in place by the depositional boundary and salt movement.
 

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California