Neogene Structural Characteristics of Louisiana Shelf with Emphasis on Growth-fault Interplay with Salt Tectonics: ABSTRACT

Abstract

Growth faulting and salt tectonics are the most pronounced structural features in the offshore Louisiana. Regional examination of seismic data(4 mile x 4 mile grid) of OCS area Suggests that polyphase halokinesis happened along the whole shelf area during the Neogene sedimentation but with different type of salt movement and faulting in time and space. The sublinear and regularly basinward-dipping lower and middle Miocene faults predominate beneath the present inner shelf region with scarcity of shallow salt features. These fault trends detached on bottom Miocene decollement related ductile shale and salt welds. The shorter and more arcuate-shaped upper Miocene and Pliocene faults complicated by abundant near-surface salt bodies characterize the farther offshore beneath the outer-shelf region. Most of these fault root into or related to salt diapirs, but at the West Cameron and at the South Timberlier, families of growth-faults were developed on the upper Miocene allochthonous salt sheet detachment and played an important role in segmenting salt sheet in this salt raft regime. The more irregularly oriented Pleistocene faults with combination of shallow basinward-dipping and counter-basinward-dipping detachment on top of large and thick upper Pliocene allochthonous salt mass occurred in the present shelf edge and slope region. This studymore » suggest at least three episodes of salt movement occurred at early Miocene, late Miocene-early Pliocene and early Pleistocene and the existence and possible position of large right-slip transfer faults.« less