Dynamic Interplay Between Channel Evolution and Seafloor Topography Linked to Rising Salt Domes, Horn Mountain, Mississippi Canyon, Gulf of Mexico

Abstract

By simultaneously examining halokinetics and channel evolution of a deepwater area it is possible to unravel the interactions between the two dynamic bodies. The study area is located in the Mississippi Canyon, Gulf of Mexico, and is situated directly off the continental slope in a prominent salt dome region. While there is a plethora of study on submarine channels in the Gulf of Mexico, their interactions with salt domes are poorly documented. Utilizing 3D seismic data and seismic geomorphology techniques, a long-lived Plio-Pleistocene submarine channel system has been investigated to understand the interaction between channel evolution and changing seascape driven by rising salt domes. In the study area, salt diapirism began to affect the seafloor topography during the late Pliocene. This shifting topography has exerted a first order control on the evolution of the meandering submarine channel, as seen in the seismic data. When investigating the channel evolution and halokinetics concurrently, a relationship becomes apparent. The study results reveal a mechanism to determine variable phases of salt movement based on plan-form morphology of preserved channels. For example, highly sinuous channels developed during periods of slow salt movement whereas straighter channels formed when salt moved upward more rapidly. Furthermore, the channels display a feedback mechanism that illustrates how areas of lower topography on the seafloor were created as the salt was reaching its diapiric state, and the channels adjusted by migrating towards these structural lows. As the channels avulsed and migrated, they were subject to an increase in slope. This increase in slope corresponds to and is directly related to a decrease in meander intensity. Thus, this study reveals how salt movement has acted as a structural control on both the location and morphology of the meandering channel complex.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015