Origin and Distribution of the Post KPG Carbonate Debris Flow and Consequent Slope Readjustment in DeSoto Canyon, Gulf of Mexico

Abstract:

The induced seismicity from the Chicxulub impact crater has been postulated as the
catalyst for the dramatic alteration and movement of sediments in the Gulf of Mexico. Previous
studies have proposed the collapse of the continental margin in the Desoto Canyon region of the
Gulf of Mexico to be associated with the extraterrestrial impact, but provide limited evidence to
support their claims. Seismic analysis of offshore two-dimensional (2D) seismic data, well logs,
and biostratigraphic data provides insight into the Paleogene history of the carbonate margin
slope failure and readjustment along the Florida escarpment. A slope’s stability is dependent on
the slope material’s shear strength, which resists slope failure, and the force of gravity, which
drives slope failure. However, the slopes of carbonate platforms are seldom homogenous and
receive and lose sediment through the complex interplay of deposition, erosion, and dissolution.
It is hypothesized the collapse of the Florida continental margin resulted in a layer of limestone
forming a steep slope due to its hardness producing a higher shear strength and angle of repose.
When this is succeeded by the deposition of siliciclastic sediments a period of slope readjustment
takes place. These finer and softer sediments are unable to assume the high slope angle of the
underlying carbonate sediments. This slope adjustment is continued throughout the Paleogene as
the out-of-grade slope of the Mass Transport Complex adjusts to reach equilibrium. The origin
and distribution of the post KPg carbonate debris flow in Desoto Canyon, Gulf of Mexico,
elucidates the complexity of out-of-grade slopes readjusting to reach its ideal angle of
sedimentation.