Salt and slope tectonics offshore Louisiana
Bally, Albert W.
Doctor of Philosophy thesis
Various stages of mid-Jurassic salt deformation resulted in post-salt extensional and contractional systems on the continental slope offshore Louisiana. Pre-mid-Cretaceous salt deformation resulted in salt massifs, small allochthonous salt bodies, pseudo-clinoforms and turtle structures. During a significant period of sediment starvation between mid-Cretaceous and mid-Oligocene time, previously formed salt and related structures remained stable. Following the reactivation of salt structures from mid-Oligocene to early-Miocene, rapid sedimentation during middle Miocene resulted in the development of large diapiric salt walls and stocks fed from the pre-mid-Cretaceous salt massifs. The rising diapiric salt structures displaced the downslope section of the rapidly deposited overburden seaward to form the Mississippi Fan Fold Belt focused near the frictional boundary along the basinward limit of the mother salt. The shortening in the fold belt ceased when the allochthonous salt began to spread near sea floor within sediments during Late Miocene. Since late Miocene, up-dip from the fold belt, large scale primary allochthonous salt sheets continued to form and spread down-slope. As massive salt withdrew from the mother salt, large primary withdrawal basins, regional, counter-regional growth fault systems, tension faults, primary and secondary welds and turtle structures formed. With increased sediment loads, the primary allochthonous salt was deformed. Consequently, supra allochthonous structures such as the secondary allochthonous salt, secondary and tertiary withdrawal basins, tertiary, quaternary and quintic welds and large extensional growth faults and occasionally contractional faults developed.